Maternal cigarette smoking, metabolic gene polymorphism, and infant birth weight

Association of pregnancy complications and postpartum maternal leukocyte telomeres in two diverse cohorts: a nested case-control study

BACKGROUND

Biologic strain such as oxidative stress has been associated with short leukocyte telomere length (LTL), as well as with preeclampsia and spontaneous preterm birth, yet little is known about their relationships with each other. We investigated associations of postpartum maternal LTL with preeclampsia and spontaneous preterm birth.

METHODS

This pilot nested case control study included independent cohorts of pregnant people with singleton gestations from two academic institutions: Cohort 1 (hereafter referred to as Suburban) were enrolled prior to 20 weeks' gestation between 2012 and 2018; and Cohort 2 (hereafter referred to as Urban) were enrolled at delivery between 2000 and 2012. Spontaneous preterm birth or preeclampsia were the selected pregnancy complications and served as cases. Cases were compared with controls from each study cohort of uncomplicated term births. Blood was collected between postpartum day 1 and up to 6 months postpartum and samples were frozen, then simultaneously thawed for analysis. Postpartum LTL was the primary outcome, measured using quantitative polymerase chain reaction (PCR) and compared using linear multivariable regression models adjusting for maternal age. Secondary analyses were done stratified by mode of delivery and self-reported level of stress during pregnancy.

RESULTS

156 people were included; 66 from the Suburban Cohort and 90 from the Urban Cohort. The Suburban Cohort was predominantly White, Hispanic, higher income and the Urban Cohort was predominantly Black, Haitian, and lower income. We found a trend towards shorter LTLs among people with preeclampsia in the Urban Cohort (6517 versus 6913 bp, p = 0.07), but not in the Suburban Cohort. There were no significant differences in LTLs among people with spontaneous preterm birth compared to term controls in the Suburban Cohort (6044 versus 6144 bp, p = 0.64) or in the Urban Cohort (6717 versus 6913, p = 0.37). No differences were noted by mode of delivery. When stratifying by stress levels in the Urban Cohort, preeclampsia was associated with shorter postpartum LTLs in people with moderate stress levels (p = 0.02).

CONCLUSION

Our exploratory results compare postpartum maternal LTLs between cases with preeclampsia or spontaneous preterm birth and controls in two distinct cohorts. These pilot data contribute to emerging literature on LTLs in pregnancy.

Associations between cord blood acetaminophen biomarkers and childhood asthma with and without allergic comorbidities

BACKGROUND

Previous studies have linked prenatal acetaminophen use to increased asthma risk in children. However, none have explored this association while differentiating between asthma cases with and without other allergic conditions or by employing objective biomarkers to assess acetaminophen exposure.

OBJECTIVE

To evaluate whether the detection of acetaminophen biomarkers in cord blood is associated with the subgroups of asthma both with and without allergic comorbidities in children.

METHODS

Acetaminophen biomarkers, including unchanged acetaminophen and acetaminophen glucuronide, were measured in neonatal cord blood samples from the Boston Birth Cohort. Asthma subgroups were defined on the basis of physician diagnoses of asthma and other allergic conditions (atopic dermatitis and allergic rhinitis). Multinomial regressions were used to evaluate the associations between acetaminophen biomarkers and asthma subgroups, adjusting for multiple confounders, including potential indications for maternal acetaminophen use such as maternal fever.

RESULTS

The study included 142 children with asthma and at least 1 other allergic condition, 55 children with asthma but no other allergic condition, and 613 children free of asthma. Detection of acetaminophen in cord blood, reflecting maternal exposure to acetaminophen shortly before delivery, was associated with 3.73 times the odds of developing asthma without allergic comorbidities (95% CI: 1.79-7.80, P = .0004). In contrast, the detection of acetaminophen in cord blood was not associated with an elevated risk of asthma with allergic comorbidities. Analysis of acetaminophen glucuronide yielded consistent results.

CONCLUSION

In a prospective birth cohort, cord blood acetaminophen biomarkers were associated with an increased risk of childhood asthma without allergic comorbidities, but were not associated with childhood asthma with allergic comorbidities.

Smoking during pregnancy and its effect on placental weight: a Mendelian randomization study

BACKGROUND

The causal relationship between maternal smoking in pregnancy and reduced offspring birth weight is well established and is likely due to impaired placental function. However, observational studies have given conflicting results on the association between smoking and placental weight. We aimed to estimate the causal effect of newly pregnant mothers quitting smoking on their placental weight at the time of delivery.

METHODS

We used one-sample Mendelian randomization, drawing data from the Avon Longitudinal Study of Parents and Children (ALSPAC) (N = 690 to 804) and the Norwegian Mother, Father and Child Cohort Study (MoBa) (N = 4267 to 4606). The sample size depends on the smoking definition used for different analyses. The analysis was performed in pre-pregnancy smokers only, due to the specific role of the single-nucleotide polymorphism (SNP) rs1051730 (CHRNA5 - CHRNA3 - CHRNB4) in affecting smoking cessation but not initiation.

RESULTS

Fixed effect meta-analysis showed a 182 g [95%CI: 29,335] higher placental weight for pre-pregnancy smoking mothers who continued smoking at the beginning of pregnancy, compared with those who stopped smoking. Using the number of cigarettes smoked per day in the first trimester as the exposure, the causal effect on placental weight was 11 g [95%CI: 1,21] per cigarette per day. Similarly, smoking at the end of pregnancy was causally associated with higher placental weight. Using the residuals of birth weight regressed on placental weight as the outcome, we showed evidence of lower offspring birth weight relative to the placental weight, both for continuing smoking at the start of pregnancy as well as continuing smoking throughout pregnancy (change in z-score birth weight adjusted for z-score placental weight: -0.8 [95%CI: -1.6,-0.1]).

CONCLUSION

Our results suggest that continued smoking during pregnancy causes higher placental weights.

Mother's age at menarche is associated with odds of preterm delivery: A case-control study

OBJECTIVE

There is a secular trend towards earlier age of menarche in the US and globally. Earlier age at menarche (AAM) has been associated with metabolic disorders that increase risk for preterm delivery (PTD), yet no studies in the US have investigated whether AAM influences risk of PTD. This study tested the hypothesis that AAM is associated with PTD.

DESIGN

A case-control study.

SETTING

The Boston Medical Center (BMC) in Boston, Massachusetts.

POPULATION OR SAMPLE

8264 mother-newborn dyads enrolled at birth at BMC between 1998 and 2019, of which 2242 mothers had PTD (cases) and 6022 did not have PTD (controls).

METHODS

Multivariable-adjusted logistic regression models and restricted cubic splines were used to examine the association between AAM and risk of PTD. The combined impact of AAM and age at delivery on the risk of PTD was also examined.

MAIN OUTCOME MEASURES

Preterm delivery and gestational age (GA) was defined by maternal last menstrual period and early ultrasound documented in medical records.

RESULTS

Maternal age at delivery was 28.1 ± 6.5 years and AAM was 12.85 ± 1.86 years. Multivariable-adjusted cubic spline suggested an inverse dose-response association of AAM with odds of PTD and, consistently, a positive association with GA. A 1-year earlier AAM was associated with 5% (95% CI 2%-8%) higher odds of PTD, after adjustment for maternal year of birth, parity, maternal place of birth, education, smoking status and Mediterranean-style diet score. The association between AAM and PTD was stronger among older mothers whose age at delivery was ≥35 years.

CONCLUSIONS

Earlier AAM is associated with higher odds for PTD, and this association is stronger among women at advanced reproductive age.

High-dimensional quantile mediation analysis with application to a birth cohort study of mother-newborn pairs

MOTIVATION

There has been substantial recent interest in developing methodology for high-dimensional mediation analysis. Yet, the majority of mediation statistical methods lean heavily on mean regression, which limits their ability to fully capture the complex mediating effects across the outcome distribution. To bridge this gap, we propose a novel approach for selecting and testing mediators throughout the full range of the outcome distribution spectrum.

RESULTS

The proposed high-dimensional quantile mediation model provides a comprehensive insight into how potential mediators impact outcomes via their mediation pathways. This method's efficacy is demonstrated through extensive simulations. The study presents a real-world data application examining the mediating effects of DNA methylation on the relationship between maternal smoking and offspring birthweight.

AVAILABILITY AND IMPLEMENTATION

Our method offers a publicly available and user-friendly function qHIMA(), which can be accessed through the R package HIMA at https://CRAN.R-project.org/package=HIMA.

The Role of the Aryl Hydrocarbon Receptor in Vascular Factors Related to Preeclampsia in a Smoking Mouse Model

Smoking cigarettes is known to lower the risk of preeclampsia. The objective of this study is to evaluate the effect of smoking on the expression of soluble FMS-like tyrosine kinase-1 (sFlt-1), vascular endothelial growth factor (VEGF), and endoglin (sEng)-1 and the role of the aryl hydrocarbon receptor (AhR) in pregnant mice. We developed a smoking mouse model using a gas-filling system. One or two cigarettes per day were exposed to each of the five pregnant mice for five days a week throughout pregnancy. AhR agonist and antagonist were injected. Serum levels and expression in the placenta of sFlt-1, VEGF, and sEng-1 were analyzed and compared among the cigarette smoke and no-exposure groups after delivery. Compared to the no-smoke exposure group, the serum level of sFlt-1 was significantly decreased in the two-cigarette-exposed group (p < 0.001). When the AhR antagonist was added to the two-cigarette-exposed group, sFlt-1 levels were significantly increased compared to the two-cigarette group (p = 0.002). The levels of sFlt-1 in the AhR antagonist group did not change regardless of two-cigarette exposure (p = 0.064). With the AhR agonist, sFlt-1 decreased significantly compared to the control (p = 0.001) and AhR antagonist group (p = 0.002). The sFlt-1 level was significantly decreased after the injection of the AhR agonist compared to the control group (p = 0.001). Serum levels of VEGF were significantly decreased in the one-cigarette-exposed group compared to the control group; however, there was no difference between the control and the two-cigarette-exposed groups. The placental expression of sFlt-1, VEGF, and sEng were inconsistent. This study offers insights into the potential role of AhR on antiangiogenic sFlt-1 associated with preeclampsia. It may support the invention of a new treatment strategy for preeclampsia using AhR activation.

Potential roles of the interactions between gut microbiota and metabolites in LPS-induced intrauterine inflammation (IUI) and associated preterm birth (PTB)

BACKGROUND

Prenatal exposure to intrauterine inflammation (IUI) is a crucial event in preterm birth (PTB) pathophysiology, increasing the incidence of neurodevelopmental disorders. Gut microbiota and metabolite profile alterations have been reported to be involved in PTB pathophysiology.

METHOD AND RESULTS

In this study, IUI-exposed PTB mouse model was established and verified by PTB rate and other perinatal adverse reactions; LPS-indued IUI significantly increased the rates of PTB, apoptosis and inflammation in placenta tissue samples. LPS-induced IUI caused no significant differences in species richness and evenness but significantly altered the species abundance distribution. Non-targeted metabolomics analysis indicated that the metabolite profile of the preterm mice was altered, and differential metabolites were associated with signaling pathways including pyruvate metabolism. Furthermore, a significant positive correlation between Parasutterella excrementihominis and S4572761 (Nb-p-coumaroyltryptamine) and Mreference-1264 (pyruvic acid), respectively, was observed. Lastly, pyruvic acid treatment partially improved LPS-induced IUI phenotypes and decreased PTB rates and decreased the apoptosis and inflammation in placenta tissue samples.

CONCLUSION

This study revealed an association among gut microbiota dysbiosis, metabolite profile alterations, and LPS-induced IUI and PTB in mice models. Our investigation revealed the possible involvement of gut microbiota in the pathophysiology of LPS-induced IUI and PTB, which might be mediated by metabolites such as pyruvic acid. Future studies should be conducted to verify the findings through larger sample-sized animal studies and clinical investigations.

Joint Associations of Pregnancy Complications and Postpartum Maternal Renal Biomarkers With Severe Cardiovascular Morbidities: A US Racially and Ethnically Diverse Prospective Birth Cohort Study

Background Pregnancy complications are risk factors for cardiovascular disease (CVD). Little is known about the role of renal biomarkers measured shortly after delivery, individually or in combination with pregnancy complications, in predicting subsequent severe maternal CVD. Methods and Results This study included 566 mothers of diverse races and ethnicities from the Boston Birth cohort, enrolled at delivery and followed prospectively. Plasma creatinine and CysC (cystatin C) were measured 1 to 3 days after delivery. CVD during follow-up was defined by physician diagnoses in electronic medical records. Associations of renal biomarkers and pregnancy complications with time-to-CVD events were assessed using Cox proportional hazards models. During an average of 10.3±3.2 years of follow-up, 30 mothers developed 1 or more CVDs. Only a modest association was observed between creatinine and risk of CVD. In comparison, we found that per 0.1 mg/L increase of CysC was associated with a hazard ratio (HR) of 1.2 (95% CI, 1.1-1.4) for CVD after adjusting for covariates. Compared with those without preeclampsia and with normal CysC level (≤75th percentile), mothers with preeclampsia and elevated CysC (>75th percentile) had the highest risk of CVD (HR, 4.6 [95% CI, 1.7-17.7]), whereas mothers with preeclampsia only or with elevated CysC only did not have significantly increased CVD risk. Similar synergistic effects for CVD were observed between CysC and preterm delivery. Conclusions In this sample of US, traditionally underrepresented multiracial and multiethnic high-risk mothers, elevated maternal plasma CysC, independently and jointly with pregnancy complications, increased risk of CVD later in life. These findings warrant further investigation. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03228875.

Newborn DNA methylation age differentiates long-term weight trajectory: The Boston Birth Cohort

Background

Gestational age (GEAA) estimated by newborn DNA methylation (GAmAge) is associated with maternal prenatal exposures and immediate birth outcomes. However, the association of GAmAge with long-term overweight or obesity (OWO) trajectories is yet to be determined.

Methods

GAmAge was calculated for 831 children from a US predominantly urban, low-income, multi-ethnic birth cohort using Illumina EPIC array and cord-blood DNA samples. Repeated anthropometric measurements aligned with pediatric primary care schedule allowed us to calculate body-mass-index percentiles (BMIPCT) at specific age and to define long-term weight trajectories from birth to 18 years.

Results

Four BMIPCT trajectory groups described the long-term weight trajectories: stable (consistent OWO: "early OWO"; constant normal weight: "NW") or non-stable (OWO by year 1 of follow-up: "late OWO"; OWO by year 6 of follow-up: "NW to very late OWO") BMIPCT. were used GAmAge was a predictor of long-term obesity, differentiating between group with consistently high BMIPCT and group with normal BMIPCT patterns and groups with late OWO development. Such differentiation can be observed in the age periods of birth to 1year, 3years, 6years, 10years, and 14years (p<0.05 for all; multivariate models adjusted for GEAA, maternal smoking, delivery method, and child's sex). Birth weight was a mediator for the GAmAge effect on OWO status for specific groups at multiple age periods.

Conclusions

GAmAge is associated with BMI trajectories from birth to age 18 years, independent of GEAA and birth weight. If further confirmed, GAmAge may serve as an early biomarker for future OWO risk.

Smoking during pregnancy and its effect on placental weight: A Mendelian randomization study

Background

The causal relationship between maternal smoking in pregnancy and reduced offspring birth weight is well established and is likely due to impaired placental function. However, observational studies have given conflicting results on the association between smoking and placental weight. We aimed to estimate the causal effect of newly pregnant mothers quitting smoking on their placental weight at the time of delivery.

Methods

We used one-sample Mendelian randomization, drawing data from the Avon Longitudinal Study of Parents and Children (ALSPAC) (up to N = 805) and the Norwegian Mother, Father and Child Cohort Study (MoBa) (up to N = 4475). The analysis was performed in pre-pregnancy smokers only, due to the specific role of the genetic instrument SNP rs1051730 (CHRNA5 - CHRNA3 - CHRNB4) in affecting smoking cessation but not initiation.

Results

Fixed effect meta-analysis showed a 175 g [95%CI: 16, 334] higher placental weight for pre-pregnancy smoking mothers who continued smoking at the beginning of pregnancy, compared with those who stopped smoking. Using the number of cigarettes smoked per day in the first trimester as the exposure, the causal estimate was a 12 g [95%CI: 2,22] higher placental weight per cigarette per day. Results were similar when the smoking exposures were measured at the end of pregnancy. Using the residuals of birth weight regressed on placental weight as the outcome, we showed weak evidence of lower offspring birth weight relative to the placental weight for continuing smoking.

Conclusion

Our results suggest that continued smoking during pregnancy causes higher placental weights.

Contrasting Association of Maternal Plasma Biomarkers of Smoking and 1-Carbon Micronutrients with Offspring DNA Methylation: Evidence of Aryl Hydrocarbon Receptor Repressor Gene-Smoking-Folate Interaction

BACKGROUND

Maternal prenatal smoking is known to alter offspring DNA methylation (DNAm). However, there are no effective interventions to mitigate smoking-induced DNAm alteration.

OBJECTIVES

This study investigated whether 1-carbon nutrients (folate, vitamins B6, and B12) can protect against prenatal smoking-induced offspring DNAm alterations in the aryl hydrocarbon receptor repressor (AHRR) (cg05575921), GFI1 (cg09935388), and CYP1A1 (cg05549655) genes.

METHODS

This study included mother-newborn dyads from a racially diverse US birth cohort. The cord blood DNAm at the above 3 sites were derived from a previous study using the Illumina Infinium MethylationEPIC BeadChip. Maternal smoking was assessed by self-report and plasma biomarkers (hydroxycotinine and cotinine). Maternal plasma folate, and vitamins B6 and B12 concentrations were obtained shortly after delivery. Linear regressions, Bayesian kernel machine regression, and quantile g-computation were applied to test the study hypothesis by adjusting for covariables and multiple testing.

RESULTS

The study included 834 mother-newborn dyads (16.7% of newborns exposed to maternal smoking). DNAm at cg05575921 (AHRR) and at cg09935388 (GFI1) was inversely associated with maternal smoking biomarkers in a dose-response fashion (all P < 7.01 × 10-13). In contrast, cg05549655 (CYP1A1) was positively associated with maternal smoking biomarkers (P < 2.4 × 10-6). Folate concentrations only affected DNAm levels at cg05575921 (AHRR, P = 0.014). Regression analyses showed that compared with offspring with low hydroxycotinine exposure (<0.494) and adequate maternal folate concentrations (quartiles 2-4), an offspring with high hydroxycotinine exposure (≥0.494) and low folate concentrations (quartile 1) had a significant reduction in DNAm at cg05575921 (M-value, ß ± SE = -0.801 ± 0.117, P = 1.44 × 10-11), whereas adequate folate concentrations could cut smoking-induced hypomethylation by almost half. Exposure mixture models further supported the protective role of adequate folate concentrations against smoking-induced aryl hydrocarbon receptor repressor (AHRR) hypomethylation.

CONCLUSIONS

This study found that adequate maternal folate can attenuate maternal smoking-induced offspring AHRR cg05575921 hypomethylation, which has been previously linked to a range of pediatric and adult diseases.

Umbilical cord DNA methylation is associated with body mass index trajectories from birth to adolescence

BACKGROUND

DNA methylation (DNAm) in cord blood has been associated with various prenatal factors and birth outcomes. This study sought to fill an important knowledge gap: the link of cord DNAm with child postnatal growth trajectories from birth to age 18 years (y).

METHODS

Using data from a US predominantly urban, low-income, multi-ethnic birth cohort (N = 831), we first applied non-parametric methods to identify body-mass-index percentile (BMIPCT) trajectories from birth to age 18 y (the outcome); then, conducted epigenome-wide association study (EWAS) of the outcome, interrogating over 700,000 CpG sites profiled by the Illumina Infinium MethylationEPIC BeadChip. Multivariate linear regression models and likelihood ratio tests (LRT) were applied to examine the DNAm-outcome association in the overall sample and sex strata.

FINDINGS

We identified four distinct patterns of BMIPCT trajectories: normal weight (NW), Early overweight or obesity (OWO), Late OWO, and normal to very late OWO. DNAm at CpG18582997 annotated to TPGS1, CpG15241084 of TLR7, and cg24350936 of RAB31 were associated with BMIPCT at birth-to-3 y, 10 y, and 14 y, respectively (LRT FDR < 0.05 for all).

INTERPRETATION

In this prospective birth cohort study, we identified 4 distinct and robust patterns of growth trajectories from birth to 18 y, which were associated with variations in cord blood DNAm at genes implicated in inflammation induction pathways. These findings, if further replicated, raise the possibility that these DNAm markers along with early assessment of BMIPCT trajectories may help identify young children at high-risk for obesity later in life.

FUNDING

Detailed in the Acknowledgements section.

Joint associations of pregnancy complications and postpartum maternal renal biomarkers with severe cardiovascular morbidities: A US racially diverse prospective birth cohort study

Rationale & Objective

Pregnancy complications are risk factors for cardiovascular diseases (CVD). Little is known about the role of renal biomarkers measured shortly after delivery, individually or in combination with pregnancy complications, in predicting subsequent severe maternal CVD.

Methods

This study included 576 mothers of diverse ethnicities from the Boston Birth cohort, enrolled at delivery and followed prospectively. Plasma creatinine and cystatin C were measured 1-3 days after delivery. CVD during follow-up was defined by physician diagnoses in electronic medical records. Associations of renal biomarkers and pregnancy complications with time-to-CVD events were assessed using Cox proportional hazards models.

Results

During an average of 10.3±3.2 years of follow-up, 34 mothers developed one or more CVD events. Although no significant associations were found between creatinine and risk of CVD, per unit increase of cystatin C (CysC) was associated with a hazard ratio (HR) of 5.21 (95%CI = 1.49-18.2) for CVD. A borderline significant interactive effect was observed between elevated CysC (≥75th percentile) and preeclampsia. Compared to those without preeclampsia and with normal CysC level (<75 th percentile), mothers with preeclampsia and elevated CysC had the highest risk of CVD (HR=3.8, 95%CI = 1.4-10.2), while mothers with preeclampsia only or with elevated CysC only did not have significantly increased CVD risk. Similar synergistic effects for CVD were observed between CysC and preterm delivery.

Conclusions

In this sample of US, traditionally under-represented multi-ethnic high-risk mothers, elevated maternal plasma cystatin C and pregnancy complications synergistically increased risk of CVD later in life. These findings warrant further investigation.

Clinical Perspectives

What is new?Maternal postpartum elevated levels of cystatin C are independently associated with higher risk of cardiovascular diseases (CVD) later in life.Maternal pregnancy complications coupled with postpartum elevated levels of cystatin C synergistically increased future risk of CVD.What are the clinical implications?These findings, if further confirmed, suggest that women with pregnancy complications and elevated postpartum cystatin C may be at particular high risk for CVD later in life compared to women without these risk factors.

Early-life determinants of childhood plasma insulin levels: implications for primordial prevention of diabetes

BACKGROUND

We earlier reported prematurity as an independent risk factor for elevated insulin levels. Investigation is still lacking on the influence of prenatal and perinatal factors on childhood insulin levels.

METHODS

In this secondary analysis of a prospective birth cohort, plasma insulin levels were measured at birth and early childhood. Regression models identified early-life factors associated with the primary outcome: log-transformed childhood plasma insulin levels.

RESULTS

One thousand one hundred and nine children had insulin levels at birth and 825 at both time points. Compared to term, preterm infants had higher plasma insulin levels (geometric mean) at birth (612, 95% CI 552-679 vs. 372, 95% CI 345-402 pmol/ml) and in early childhood (547, 95% CI 494-605 vs. 445, 95% CI 417-475 pmol/ml). Factors associated with higher early childhood insulin levels included higher insulin level at birth, black race, female sex, maternal smoking during pregnancy, maternal perceived stress, in utero drug exposure, maternal pregestational diabetes mellitus, and maternal preconception overweight and obesity.

CONCLUSIONS

In this high-risk US birth cohort, we identified multiple prenatal and perinatal risk factors for higher early childhood insulin levels, in addition to prematurity. These findings lend support to primordial preventive strategies for diabetes mellitus.

IMPACT

In this secondary analysis of a large prospective study from a high-risk racially diverse cohort, we identify biological and social factors that contribute to elevated levels of plasma insulin in early childhood. Our study also investigates factors affecting plasma insulin in preterm infants along with comorbidities commonly seen during the neonatal intensive care stay. Our work reaffirms the importance of Developmental Origins of Health and Disease with regards to in utero programming of insulin levels. Our work supports the possibility that primordial preventive strategies for diabetes mellitus in high-risk populations may need to begin as early as the prenatal period.

DNA methylation as a potential mediator of the association between prenatal tobacco and alcohol exposure and child neurodevelopment in a South African birth cohort

Prenatal tobacco exposure (PTE) and prenatal alcohol exposure (PAE) have been associated with an increased risk of delayed neurodevelopment in children as well as differential newborn DNA methylation (DNAm). However, the biological mechanisms connecting PTE and PAE, DNAm, and neurodevelopment are largely unknown. Here we aim to determine whether differential DNAm mediates the association between PTE and PAE and neurodevelopment at 6 (N = 112) and 24 months (N = 184) in children from the South African Drakenstein Child Health Study. PTE and PAE were assessed antenatally using urine cotinine measurements and the ASSIST questionnaire, respectively. Cord blood DNAm was measured using the EPIC and 450 K BeadChips. Neurodevelopment (cognitive, language, motor, adaptive behavior, socioemotional) was measured using the Bayley Scales of Infant and Toddler Development, Third Edition. We constructed methylation risk scores (MRS) for PTE and PAE and conducted causal mediation analysis (CMA) with these MRS as mediators. Next, we conducted a high-dimensional mediation analysis to identify individual CpG sites as potential mediators, followed by a CMA to estimate the average causal mediation effects (ACME) and total effect (TE). PTE and PAE were associated with neurodevelopment at 6 but not at 24 months. PTE MRS reached a prediction accuracy (R2) of 0.23 but did not significantly mediate the association between PTE and neurodevelopment. PAE MRS was not predictive of PAE (R2 = 0.006). For PTE, 31 CpG sites and eight CpG sites were identified as significant mediators (ACME and TE P < 0.05) for the cognitive and motor domains at 6 months, respectively. For PAE, 16 CpG sites and 1 CpG site were significant mediators for the motor and adaptive behavior domains at 6 months, respectively. Several of the associated genes, including MAD1L1, CAMTA1, and ALDH1A2 have been implicated in neurodevelopmental delay, suggesting that differential DNAm may partly explain the biological mechanisms underlying the relationship between PTE and PAE and child neurodevelopment.

Genes, exposures, and interactions on preterm birth risk: an exploratory study in an Argentine population

Preterm birth (PTB) is the main condition related to perinatal morbimortality worldwide. The aim of this study was to identify associations of spontaneous PTB with genetic variants, exposures, and interactions between and within them. We carried out a retrospective case-control study including parental sociodemographic and obstetric data, and fetal genetic variants. We sequenced the coding and flanking regions of five candidate genes from the placental blood cord of 69 preterm newborns and 61 at term newborns. We identify the characteristics with the greatest predictive power of PTB using penalized regressions, in which we include exposures (E), genetic variants (G), and two-way interactions. Few prenatal visits (< 5) was the main predictor of PTB from 26 G, 35 E, 299 G × G, 564 E × E, and 875 G × E evaluated terms. Within the fetal genetic characteristics, we observed associations of rs4845397 (KCNN3, allele T) variant; G × G interaction between rs12621551 (COL4A3, allele T) and rs73993878 (COL4A3, allele A), which showed sensitivity to anemia; and G × G interaction between rs11680670 (COL4A3, allele T) and rs2074351 (PON1, allele A), which showed sensitivity to vaginal discharge. The results of this exploratory study suggest that social disparities and metabolic pathways linked to uterine relaxation, inflammation/infections, and collagen metabolism would be involved in PTB etiology. Future studies with a larger sample size are necessary to confirm these findings and to analyze a greater number of exposures.

Developmental disorders in children born to women with sickle cell disease: A report from the Boston Birth Cohort

Children exposed to maternal sickle cell disease (SCD) have many theoretical risks for developmental disorders, but little is known about long‐term outcomes for these children. We used the Boston Birth Cohort to compare developmental outcomes between children exposed to maternal SCD and matched, unexposed controls. Children with exposure to maternal SCD had increased risk of attention deficit hyperactivity disorder (OR 5.12, 95% CI 1.36–19.19, p = 0.02) and obesity (OR 2.74, 95% CI 1.10–6.87, p = 0.03). In utero and/or environmental exposures may help explain these findings. Further studies of outcomes of children born to women with SCD are needed.

Association between cord blood metabolites in tryptophan pathway and childhood risk of autism spectrum disorder and attention-deficit hyperactivity disorder

Alterations in tryptophan and serotonin have been implicated in various mental disorders; but studies are limited on child neurodevelopmental disabilities such as autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD). This prospective cohort study examined the associations between levels of tryptophan and select metabolites (5-methoxytryptophol (5-MTX), 5-hydroxytryptophan (5-HTP), serotonin, N-acetyltrytophan) in cord plasma (collected at birth) and physician-diagnosed ASD, ADHD and other developmental disabilities (DD) in childhood. The study sample (n = 996) derived from the Boston Birth Cohort, which included 326 neurotypical children, 87 ASD, 269 ADHD, and 314 other DD children (mutually exclusive). These participants were enrolled at birth and followed-up prospectively (from October 1, 1998 to June 30, 2018) at the Boston Medical Center. Higher levels of cord 5-MTX was associated with a lower risk of ASD (aOR: 0.56, 95% CI: 0.41, 0.77) and ADHD (aOR: 0.79, 95% CI: 0.65, 0.96) per Z-score increase, after adjusting for potential confounders. Similarly, children with cord 5-MTX ≥ 25th percentile (vs. <25th percentile) had a reduction in ASD (aOR: 0.27, 95% CI: 0.14, 0.49) and ADHD risks (aOR: 0.45, 95% CI: 0.29, 0.70). In contrast, higher levels of cord tryptophan, 5-HTP and N-acetyltryptophan were associated with higher risk of ADHD, with aOR: 1.25, 95% CI: 1.03, 1.51; aOR: 1.32, 95% CI: 1.08, 1.61; and aOR: 1.27, 95% CI: 1.05, 1.53, respectively, but not with ASD and other DD. Cord serotonin was not associated with ASD, ADHD, and other DD. Most findings remained statistically significant in the sensitivity and subgroup analyses.

Trimethylamine N-Oxide and Its Precursors Are Associated with Gestational Diabetes Mellitus and Pre-Eclampsia in the Boston Birth Cohort

Background

Trimethylamine N-oxide (TMAO) and its precursors choline, betaine, and carnitine have been associated with cardiometabolic disease in nonpregnant adults. However, studies examining TMAO and its precursors in relation to cardiometabolic conditions during pregnancy are lacking.

Objectives

The primary objective was to estimate the association of TMAO and its precursors in maternal and cord plasma with gestational diabetes mellitus (GDM) and pre-eclampsia (PE) among women in the Boston Birth Cohort. A secondary objective was to determine whether associations vary by race/ethnicity.

Methods

ORs for each outcome according to tertiles and to an SD increment of TMAO, choline, betaine, and carnitine were estimated using logistic regression. Final models were adjusted for covariates.

Results

Among 1496 women, 115 women had GDM and 159 had PE during the index pregnancy. Intermetabolite correlations of TMAO and its precursors were stronger within cord plasma (r = 0.38-0.87) than within maternal plasma (r = 0.08-0.62). Maternal TMAO was associated with higher odds of GDM (third compared with first tertile OR: 1.75; 95% CI: 1.04, 2.94), whereas maternal choline, betaine, and carnitine were not associated with GDM. Maternal TMAO and choline were not associated with PE, whereas carnitine was associated with higher (OR: 1.86; 95% CI: 1.18, 2.94) and betaine with lower odds of PE (OR: 0.37; 95% CI: 0.23, 0.59). In cord plasma, TMAO was not associated with GDM or PE, but choline, betaine, and carnitine were associated with higher odds of PE (OR: 3.11; 95% CI: 1.62, 5.96; OR: 2.65; 95% CI: 1.42, 4.93; OR: 2.56; 95% CI: 1.39, 4.69, respectively). Cord choline was associated with lower odds of GDM (OR: 0.52; 95% CI: 0.27, 0.99), whereas other cord metabolites were not significantly associated with GDM. Associations did not vary by race/ethnicity.

Conclusions

TMAO and its precursors were associated with GDM and PE, but the associations differed based on the metabolite medium (maternal compared with cord plasma).This trial was registered at clinicaltrials.gov as NCT03228875.

Paternal eNOS deficiency in mice affects glucose homeostasis and liver glycogen in male offspring without inheritance of eNOS deficiency itself

AIMS/HYPOTHESIS

It was shown that maternal endothelial nitric oxide synthase (eNOS) deficiency causes fatty liver disease and numerically lower fasting glucose in female wild-type offspring, suggesting that parental genetic variants may influence the offspring's phenotype via epigenetic modifications in the offspring despite the absence of a primary genetic defect. The aim of the current study was to analyse whether paternal eNOS deficiency may cause the same phenotype as seen with maternal eNOS deficiency.

METHODS

Heterozygous (+/-) male eNOS (Nos3) knockout mice or wild-type male mice were bred with female wild-type mice. The phenotype of wild-type offspring of heterozygous male eNOS knockout mice was compared with offspring from wild-type parents.

RESULTS

Global sperm DNA methylation decreased and sperm microRNA pattern altered substantially. Fasting glucose and liver glycogen storage were increased when analysing wild-type male and female offspring of +/- eNOS fathers. Wild-type male but not female offspring of +/- eNOS fathers had increased fasting insulin and increased insulin after glucose load. Analysing candidate genes for liver fat and carbohydrate metabolism revealed that the expression of genes encoding glucocorticoid receptor (Gr; also known as Nr3c1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc1a; also known as Ppargc1a) was increased while DNA methylation of Gr exon 1A and Pgc1a promoter was decreased in the liver of male wild-type offspring of +/- eNOS fathers. The endocrine pancreas in wild-type offspring was not affected.

CONCLUSIONS/INTERPRETATION

Our study suggests that paternal genetic defects such as eNOS deficiency may alter the epigenome of the sperm without transmission of the paternal genetic defect itself. In later life wild-type male offspring of +/- eNOS fathers developed increased fasting insulin and increased insulin after glucose load. These effects are associated with increased Gr and Pgc1a gene expression due to altered methylation of these genes.

Gene-environment interactions related to maternal exposure to environmental and lifestyle-related chemicals during pregnancy and the resulting adverse fetal growth: a review

Background

There are only limited numbers of reviews on the association of maternal-child genetic polymorphisms and environmental and lifestyle-related chemical exposure during pregnancy with adverse fetal growth. Thus, this article aims to review: (1) the effect of associations between the above highlighted factors on adverse fetal growth and (2) recent birth cohort studies regarding environmental health risks.

Methods

Based on a search of the PubMed database through August 2021, 68 epidemiological studies on gene-environment interactions, focusing on the association between environmental and lifestyle-related chemical exposure and adverse fetal growth was identified. Moreover, we also reviewed recent worldwide birth cohort studies regarding environmental health risks.

Results

Thirty studies examined gene-smoking associations with adverse fetal growth. Sixteen maternal genes significantly modified the association between maternal smoking and adverse fetal growth. Two genes significantly related with this association were detected in infants. Moreover, the maternal genes that significantly interacted with maternal smoking during pregnancy were cytochrome P450 1A1 (CYP1A1), X-ray repair cross-complementing protein 3 (XRCC3), interleukin 6 (IL6), interleukin 1 beta (IL1B), human leukocyte antigen (HLA) DQ alpha 1 (HLA-DQA1), HLA DQ beta 1 (HLA-DQB1), and nicotinic acetylcholine receptor. Fetal genes that had significant interactions with maternal smoking during pregnancy were glutathione S-transferase theta 1 (GSTT1) and fat mass and obesity-associated protein (FTO). Thirty-eight studies examined the association between chemical exposures and adverse fetal growth. In 62 of the 68 epidemiological studies (91.2%), a significant association was found with adverse fetal growth. Across the studies, there was a wide variation in the analytical methods used, especially with respect to the genetic polymorphisms of interest, environmental and lifestyle-related chemicals examined, and the study design used to estimate the gene-environment interactions. It was also found that a consistently increasing number of European and worldwide large-scale birth cohort studies on environmental health risks have been conducted since approximately 1996.

Conclusion

There is some evidence to suggest the importance of gene-environment interactions on adverse fetal growth. The current knowledge on gene-environment interactions will help guide future studies on the combined effects of maternal-child genetic polymorphisms and exposure to environmental and lifestyle-related chemicals during pregnancy.

Supplementary information

The online version contains supplementary material available at https://doi.org/10.1265/ehpm.21-00033.

Maternal Glycemic Spectrum and Adverse Pregnancy and Perinatal Outcomes in a Multiracial US Cohort

Diabetes mellitus (pregestational (PDM) and gestational (GDM)) is associated with adverse pregnancy outcomes (APOs). However, studies exploring the association of APOs with maternal glycemia among women without PDM/GDM are limited. We utilized data from 4119 women (307-PDM; 582-GDM; 3230-non-PDM/GDM) in the Boston Birth Cohort (1998-2016). Women in the non-PDM/GDM group were subdivided by tertiles of 1 h, 50 g oral glucose load test at 24-32 weeks: T1: 50-95 mg/dL (n = 1166), T2: 96-116 mg/dL (n = 1151), T3: 117-201 mg/dL (n = 913). Using multivariable logistic regression, we examined the association of maternal glycemia with APOs-preterm birth (PTB) and hypertensive disorders of pregnancy (HDP)-and adverse perinatal outcomes-high birth weight (HBW), cesarean section (CS), and sub-analyses by race-ethnicity. Compared to women in T1, women in T2 and T3 had a higher prevalence of pre-existing hypertension (T1: 2.8% vs. T2: 5.2% vs. T3: 6.3%) and obesity (T1: 13.3% vs. T2: 18.1% vs. T3: 22.9%). Women in T2 and T3 had higher odds of HBW (adjusted odds ratio aOR T2: 1.47 [1.01-2.19] T3: 1.68 [1.13-2.50]) compared to women in T1. Additionally, women in T2, compared to T1, had higher odds of HDP (aOR 1.44 [1.10-1.88]). Among non-Hispanic Black (NHB) women, those in T2 and T3 had higher odds of HDP compared to T1 (aOR T2 1.67 [1.13-2.51]; T3: 1.68 [1.07-2.62]). GDM and PDM were associated with higher odds of HBW, CS, PTB, and HDP, compared to women in T1. In this predominantly NHB and Hispanic cohort, moderate maternal glycemia without PDM/GDM was associated with higher odds of HBW and HDP, even more strongly among NHB women. If confirmed, a review of current guidelines of glucose screening and risk stratification in pregnancy may be warranted.

Nativity-Related Disparities in Preterm Birth and Cardiovascular Risk in a Multiracial U.S. Cohort

INTRODUCTION

Having a preterm birth is associated with future cardiovascular risk. Non-Hispanic Black women have higher rates of preterm birth than non-Hispanic White and Hispanic women, but nativity-related disparities in preterm birth are not well understood.

METHODS

Data from 6,096 women in the Boston Birth Cohort: non-Hispanic Black (2,699), non-Hispanic White (997), or Hispanic (2,400), were analyzed in June 2021. Differences in cardiovascular risk factors were assessed. The association of preterm birth with nativity and duration of U.S. residence were investigated using multivariable logistic regression.

RESULTS

U.S.-born women in all 3 racial-ethnic groups had a higher prevalence of obesity, smoking, and severe stress than foreign-born women. Foreign-born non-Hispanic Black and Hispanic women had lower odds of preterm birth than U.S.-born counterparts (non-Hispanic Black: AOR=0.79, 95% CI=0.65, 0.97; Hispanic: AOR=0.72, 95% CI=0.56, 0.93). In all the 3 groups, foreign-born women with shorter (<10 years) duration of U.S. residence had lower odds of preterm birth than the U.S.-born women (non-Hispanic Black: AOR=0.57, 95% CI=0.43, 0.75; Hispanic: AOR=0.72, 95% CI=0.55, 0.94; non-Hispanic White: AOR=0.46, 95% CI=0.25, 0.85), whereas the odds of preterm birth in foreign-born women with ≥10 years of residence were not significantly different.

CONCLUSIONS

Foreign-born women had better cardiovascular risk profiles in all groups and lower odds of preterm birth in non-Hispanic Black and Hispanic groups. In all the 3 groups, a shorter duration of U.S. residence was associated with lower odds of preterm birth. Further studies are needed to understand the biological and social determinants underlying these nativity-related disparities and the impact of acculturation.

Risk factors associated with low birth weight

OBJECTIVES

Low birth weight (LBW) is one of the major factors affecting child morbidity and mortality worldwide. Every day, approximately 800 women die from causes related to pregnancy and childbirth worldwide. Maternal ill health increases the risk of LBW. This study seeks to investigate determinants and incidence of LBW.

METHODS

This study was conducted based on the medical records of mothers and their 1,946 infants born in 2016-2019 at the Department of Gynaecology and Obstetrics of Louis Pasteur University Hospital in Košice. Data on mothers and newborn infants were obtained from the Reports on mothers at childbirth. The inclusion criteria were singleton births and birth weight > 500 g. The exclusion criteria were twins or multiple births, congenital anomalies and stillbirths, birth weight ≥ 4,000 g or ≤ 500 g, and Roma ethnicity. Roma children are more likely to be born prematurely, with low birth weight. Roma mothers have different lifestyle. Univariate analysis was employed to evaluate the association between the independent variables and LBW. Variables that were found to be statistically significant were then further analysed using multivariable logistic analysis for each dependent variable. The implementation of the research was approved by the Ethics Committee.

RESULTS

Of 1,946 newborns, 271 (13.90%) have low birth weight. The mean of birth weight at delivery was 3,068.62 (SD 671.16) grams. Factors that were associated with LBW were primary maternal education (OR = 2.98, 95% CI: 1.08-8.21, p = 0.034), marital status single (OR = 2.88, 95% CI: 1.68-4.94, p < 0.001), number of prenatal care visits less than 8 (OR = 1.62, 95% CI: 1.01-2.61, p = 0.047), and preterm birth (OR = 74.94, 95% CI: 45.44-123.61, p < 0.001).

CONCLUSION

The reducing of LBW requires strategies to improve maternal lifestyle, maternal care before, during and after birth and to strengthen social support.

Maternal nicotine metabolism moderates the impact of maternal cigarette smoking on infant birth weight: A Collaborative Perinatal Project investigation

BACKGROUND

Maternal cigarette smoking is an important modifiable risk factor for low birth weight in the US. We investigated the maternal nicotine metabolite ratio (NMR; trans-3'-hydroxycotinine/cotinine) - a genetically-informed biomarker of nicotine clearance - as a moderator of links between prenatal cigarette use and birth weight. We also explored the role of race in these associations.

METHODS

Participants were 454 pregnant women (M_age = 25 years; 11% Black) who smoked cigarettes and their 537 infants from the Collaborative Perinatal Project. Cigarettes smoked per day were assessed at each prenatal visit; maternal NMR was assayed from third trimester serum. Birth weight was obtained from medical records. Generalized estimating equations were used to evaluate associations between cigarette smoking, NMR, race, and birth weight.

RESULTS

NMR moderated continuous associations between cigarettes per day over pregnancy and infant birth weight (p = .025). Among women who smoked at moderate levels (<15 cigarettes per day), those with slower NMR showed ~50-100 g decrements in birth weight versus those with faster NMR., while there were no significant associations between NMR and birth weight among women who smoked 15+ cigarettes per day. Although effects of NMR on birthweight were similar for Black and white women, Black women showed significantly slower NMR (p < .001).

CONCLUSIONS

This is the first demonstration that the maternal nicotine metabolism phenotype moderates associations between maternal smoking during pregnancy and birth weight. Infants of women with slower nicotine metabolism - including disproportionate representation of Black women - may be at heightened risk for morbidity from maternal smoking.

Individual and Combined Association Between Prenatal Polysubstance Exposure and Childhood Risk of Attention-Deficit/Hyperactivity Disorder

IMPORTANCE

Polysubstance use among pregnant women has increased because of the opioid epidemic and the increasing legalization of cannabis along with persistent tobacco and alcohol consumption. Previous research on prenatal substance use and the child's risk of attention-deficit/hyperactivity disorder (ADHD) has mostly focused on single-substance exposures; simultaneous examination of multiple substance use and assessment of their synergistic health consequences is needed.

OBJECTIVES

To assess the consequences of the use of specific substances during pregnancy, investigate whether the interaction of multiple prenatal substance exposures is associated with increases in the risk of childhood ADHD, and estimate the aggregate burden of polysubstance exposure during gestation.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed data from the Boston Birth Cohort from 1998 to 2019. The sample of the present study comprised a multiethnic urban cohort of mother-child pairs who were predominantly low income. A total of 3138 children who were enrolled shortly after birth at Boston Medical Center were included and followed up from age 6 months to 21 years.

EXPOSURES

Substance use during pregnancy was identified based on self-reported tobacco smoking, alcohol consumption, and use of cannabis, cocaine, or opioids in any trimester of pregnancy. Diagnostic codes for neonatal opioid withdrawal syndrome or neonatal abstinence syndrome from the International Classification of Diseases, Ninth Revision, and the International Classification of Diseases, Tenth Revision, were also used to identify opioid exposure during gestation.

MAIN OUTCOMES AND MEASURES

ADHD diagnosis in the child's electronic medical record.

RESULTS

Among 3138 children (1583 boys [50.4%]; median age, 12 years [IQR, 9-14 years]; median follow-up, 10 years [IQR, 7-12 years]) in the final analytic sample, 486 (15.5%) had an ADHD diagnosis and 2652 (84.5%) were neurotypical. The median postnatal follow-up duration was 12 years (IQR, 9-14 years). Among mothers, 46 women (1.5%) self-identified as Asian (non-Pacific Islander), 701 (22.3%) as Hispanic, 1838 (58.6%) as non-Hispanic Black, 227 (7.2%) as non-Hispanic White, and 326 (10.4%) as other races and/or ethnicities (including American Indian or Indigenous, Cape Verdean, Pacific Islander, multiracial, other, or unknown). A total of 759 women (24.2%) reported the use of at least 1 substance during pregnancy, with tobacco being the most frequently reported (580 women [18.5%]). Cox proportional hazards models revealed that opioid exposure (60 children) had the highest adjusted hazard ratio (HR) for ADHD (2.19; 95% CI, 1.10-4.37). After including main statistical effects of all individual substances in an elastic net regression model, the HR of opioids was reduced to 1.60, and evidence of a statistical interaction between opioids and both cannabis and alcohol was found, producing 1.42 and 1.15 times higher risk of ADHD, respectively. The interaction between opioids and smoking was also associated with a higher risk of ADHD (HR, 1.17).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that it is important to consider prenatal concurrent exposure to multiple substances and their possible interactions when counseling women regarding substance use during pregnancy, the future risk of ADHD for their children, and strategies for cessation and treatment programs.

Fetal lipidome and incident risk of food allergy: A prospective birth cohort study

BACKGROUND

Lipids are proposed to be important in developing adaptive immunity and allergy. However, studies to date reported inconsistent findings.

OBJECTIVE

To examine newborn lipidome (a comprehensive profiling of circulating lipid metabolites) on child's risk of developing food allergy (FA). The maternal-cord joint effects of lipid metabolites on FA development were also investigated.

METHODS

This study included 647 mother-child pairs from the Boston Birth Cohort and analyzed 202 lipid metabolites in cord plasma profiled by liquid chromatography tandem mass spectrometry. FA was defined based on standard clinical criteria. Logistic regression was applied to examine the relationships between individual metabolites and risk of FA.

RESULTS

Of the 647 children, 61 developed FA. Cord triacylglycerols of long carbon chains and multiple double bonds were significantly associated with decreased risk of FA. These associations were comparable across strata of pertinent maternal and child covariates, and were independent of maternal triacylglycerols when assessed simultaneously. Besides, cord and maternal triacylglycerols had an additive effect in association with risk of FA: Children having high (≥Median) C56:8 triacylglycerol levels in both cord and maternal plasma were at the lowest risk of developing FA (OR = 0.24, 95% CI = 0.10-0.56, p = .001), compared to those having low levels in both cord and maternal plasma.

CONCLUSION

This is the first birth cohort study to link altered cord plasma lipidome with future risk of development FA during childhood. It calls for further investigation on triacylglycerols of long carbon chains and multiple double bonds as potential novel predictive biomarkers and therapeutic targets for FA.

Racial Disparities in Gestational Diabetes by Maternal Nativity and Length of US Residence in an Urban Low-income Population in the United States

Background

Gestational diabetes mellitus (GDM) is associated with increased risk of cardiovascular disease (CVD). Racial/ethnic differences in GDM prevalence have been described, but disparities by nativity and duration of US residence are not well studied.

Methods

We analyzed data from 6088 women (mean age: 27.5 years [standard deviation: 6.3 years]) from the Boston Birth Cohort who self-identified as non-Hispanic Black (NHB; n = 2697), Hispanic (n = 2395), or non-Hispanic White (NHW; n = 996). Using multivariable logistic regression, we examined the cross-sectional association of nativity and duration of US residence (< 10 vs ≥ 10 years) with GDM within each race/ethnicity group.

Results

Foreign-born NHB, NHW, and Hispanic women with a duration of US residence of < 10 years had a lower prevalence of CVD risk factors than those with US residence of ≥ 10 years, respectively, as follows: smoking (NHB: 1.7% vs 3.1%; NHW: 5.7% vs 8.1%; Hispanic: 0.4% vs 2.6%); obesity (NHB: 17.1% vs 23.4%; NHW: 3.8% vs 15.6%; Hispanic: 10.9% vs 22.7%); and severe stress (NHB: 8.7% vs 11.9%; NHW: 5.7% vs 28.1%; Hispanic: 3.8% vs 7.3%). In analyses adjusting for sociodemographic characteristics and CVD risk factors, foreign-born NHB women with a duration of US residence of < 10 years had higher odds of having GDM (adjusted odds ratio: 1.60, 95% confidence interval: 0.99-2.60), compared with their US-born counterparts, whereas foreign-born Hispanic women with a duration of US residence of < 10 years had lower odds of having GDM (adjusted odds ratio: 0.54, 95% confidence interval: 0.32-0.91). The odds of having GDM in Hispanic and NHB women with a duration of US residence of ≥ 10 years were not significantly different from those of their US-born counterparts.

Conclusions

The “healthy immigrant effect” and its waning with longer duration of US residence apply to the prevalence of GDM among Hispanic women but not NHB women. Further research on the intersectionality of race and nativity-based disparities is needed.

Effects of Stress and Nativity on Maternal Antenatal Substance Use and Postnatal Mental Disorders

Background: Maternal substance use and common mental disorders (CMDs) during or after pregnancy can lead to negative health outcomes among mothers and infants. We examined whether nativity (US-born versus foreign-born) and stress levels during pregnancy were associated with antenatal substance use and postnatal CMDs. Methods: We analyzed the Boston Birth Cohort, a racially diverse cohort recruited at birth with rolling enrollment since 1998. Information on antenatal substance use (tobacco and/or alcohol use) was obtained using an in-person postpartum questionnaire (n = 6,514). Information on postnatal CMDs (depression and/or anxiety) was obtained from medical records (n = 2,052). Nativity and stress during pregnancy were self-reported. We performed multivariate logistic regression to examine how nativity and stress levels were jointly associated with antenatal substance use and postnatal CMDs. We further investigated if blacks, Hispanics, and whites were differentially at risk. Results: We found that US-born mothers were at higher risk of substance use and CMDs than their foreign-born counterparts. In analyses combining nativity and stress, being US-born with high stress was associated with increased odds of antenatal substance use (adjusted odds ratio [aOR] = 14.91, 95% confidence interval [CI]: 12.09-18.39) and postnatal CMDs (aOR = 4.09, 95% CI: 2.72-6.15) compared with foreign-born mothers with low stress. The results of the subanalyses limited to black and Hispanic women separately were similar; high stress alone was associated with fourfold increased odds of CMDs among foreign-born Hispanic mothers (aOR = 4.27, 95% CI: 1.96-9.33). Conclusions: Findings suggest that identifying and alleviating high stress among pregnant women may reduce their risk of antenatal substance use and postnatal CMDs.

Focus on Early COPD: Definition and Early Lung Development

Chronic obstructive pulmonary disease (COPD) is a disease with high incidence rate and mortality rates worldwide. It is the third leading cause of death in the world. Nevertheless, little progress has been made in treating and preventing the disease. Under these circumstances, the concept of “early COPD” was proposed. Although this concept is not new, most health-care workers do not fully understand early COPD and tend to confuse it with mild COPD. In this review, we mainly discuss the definition of early COPD and the developmental trajectory of lung function. Although patients with early COPD have no symptoms, their lung function is already lower than that of normal people. A relatively complete definition is needed to identify this group of people. Reduced lung function is the diagnostic criterion for COPD, but lung development is a long-term dynamic process. In addition to smoking and air pollution, we should pay more attention to prenatal and childhood risk factors, for example, parents smoking, birth weight, preterm birth, mode of delivery, childhood respiratory infections and childhood asthma. Health-care workers need to be fully aware of early COPD, to reduce the morbidity of COPD and take effective measures to prevent these risk factors.

Interaction of maternal asthma history and plasma folate levels on child asthma risk in the Boston Birth Cohort

BACKGROUND

Previous studies on maternal folate status during pregnancy and child asthma risk yielded mixed results, and few considered maternal asthma history, a known risk factor of childhood asthma. This study examined whether the role of maternal folate in childhood asthma differs by maternal asthma history and whether there is an interaction between the two factors.

METHODS

This study included 1948 mother-child dyads from the Boston Birth Cohort. Childhood asthma was defined based on physician diagnosis documented in electronic medical records, and maternal asthma was based on standard questionnaire interview. Maternal plasma folate level within a few days of delivery was measured by chemiluminescent immunoassay. Logistic regression models were applied to examine individual and joint associations of maternal asthma history and plasma folate level with childhood asthma, adjusting for other covariables.

RESULTS

When stratified by maternal asthma history, an L-shaped relationship between maternal folate level and child asthma was observed in children born to mothers with asthma history (p_interaction  = 0.03). The highest risk was found in children having maternal asthma history and low maternal folate level (odds ratio = 5.93; 95% confidence interval: 2.86-12.3) compared with children without maternal asthma history and with sufficient maternal folate levels. Sensitivity analyses using different definitions of asthma and stratified by major covariables yielded similar findings.

CONCLUSION

In this US prospective high-risk birth cohort, maternal asthma history and low folate level interactively increased the risk of child asthma. If further confirmed, optimizing maternal folate levels during pregnancy may mitigate child asthma risk in the setting of maternal asthma history.

Nativity-Related Disparities in Preeclampsia and Cardiovascular Disease Risk Among a Racially Diverse Cohort of US Women

IMPORTANCE

Preeclampsia is an independent risk factor for future cardiovascular disease and disproportionally affects non-Hispanic Black women. The association of maternal nativity and duration of US residence with preeclampsia and other cardiovascular risk factors is well described among non-Hispanic Black women but not among women of other racial and ethnic groups.

OBJECTIVE

To examine differences in cardiovascular risk factors and preeclampsia prevalence by race and ethnicity, nativity, and duration of US residence among Hispanic, non-Hispanic Black, and non-Hispanic White women.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional analysis of the Boston Birth Cohort included a racially diverse cohort of women who had singleton deliveries at the Boston Medical Center from October 1, 1998, to February 15, 2016. Participants self-identified as Hispanic, non-Hispanic Black, or non-Hispanic White. Data were analyzed from March 1 to March 31, 2021.

EXPOSURES

Maternal nativity and duration of US residence (<10 vs ≥10 years) were self-reported.

MAIN OUTCOME AND MEASURES

Diagnosis of preeclampsia, the outcome of interest, was retrieved from maternal medical records.

RESULTS

A total of 6096 women (2400 Hispanic, 2699 non-Hispanic Black, and 997 non-Hispanic White) with a mean (SD) age of 27.5 (6.3) years were included in the study sample. Compared with Hispanic and non-Hispanic White women, non-Hispanic Black women had the highest prevalence of chronic hypertension (204 of 2699 [7.5%] vs 65 of 2400 [2.7%] and 28 of 997 [2.8%], respectively), obesity (658 of 2699 [24.4%] vs 380 of 2400 [15.8%] and 152 of 997 [15.2%], respectively), and preeclampsia (297 of 2699 [11.0%] vs 212 of 2400 [8.8%] and 71 of 997 [7.1%], respectively). Compared with their counterparts born outside the US, US-born women in all 3 racial and ethnic groups had a significantly higher prevalence of obesity (Hispanic women, 132 of 556 [23.7%] vs 248 of 1844 [13.4%]; non-Hispanic Black women, 444 of 1607 [27.6%] vs 214 of 1092 [19.6%]; non-Hispanic White women, 132 of 776 [17.0%] vs 20 of 221 [9.0%]), smoking (Hispanic women, 98 of 556 [17.6%] vs 30 of 1844 [1.6%]; non-Hispanic Black women, 330 of 1607 [20.5%] vs 53 of 1092 [4.9%]; non-Hispanic White women, 382 of 776 [49.2%] vs 42 of 221 [19.0%]), and severe stress (Hispanic women, 76 of 556 [13.7%] vs 85 of 1844 [4.6%]; non-Hispanic Black women, 231 of 1607 [14.4%] vs 120 of 1092 [11.0%]; non-Hispanic White women, 164 of 776 [21.1%] vs 26 of 221 [11.8%]). After adjusting for sociodemographic and cardiovascular risk factors, birth status outside the US (adjusted odds ratio [aOR], 0.74 [95% CI, 0.55-1.00]) and shorter duration of US residence (aOR, 0.62 [95% CI, 0.41-0.93]) were associated with lower odds of preeclampsia among non-Hispanic Black women. However, among Hispanic and non-Hispanic White women, maternal nativity (aOR for Hispanic women, 1.07 [95% CI, 0.72-1.60]; aOR for non-Hispanic White women, 0.98 [95% CI, 0.49-1.96]) and duration of US residence (aOR for Hispanic women <10 years, 1.04 [95% CI, 0.67-1.59]; aOR for non-Hispanic White women <10 years, 1.20 [95% CI, 0.48-3.02]) were not associated with preeclampsia.

CONCLUSIONS AND RELEVANCE

Nativity-related disparities in preeclampsia persisted among non-Hispanic Black women but not among Hispanic and non-Hispanic White women after adjusting for sociodemographic and cardiovascular risk factors. Further research is needed to explore the interplay of factors contributing to nativity-related disparities in preeclampsia, particularly among non-Hispanic Black women.

The Association of Preterm Birth With Maternal Nativity and Length of Residence Among Non-Hispanic Black Women

Background

Preterm birth (PTB) is associated with future cardiovascular disease (CVD) risk and disproportionally affects non-Hispanic Black (NHB) women. Limited data exist on the influence of length of US residence on nativity-related disparities in PTB. We examined PTB by maternal nativity (US born vs foreign born) and length of US residence among NHB women.

Methods

We analyzed data from 2699 NHB women (1607 US born; 1092 foreign born) in the Boston Birth Cohort, originally designed as a case-control study. Using multivariable logistic regression, we investigated the association of PTB with maternal nativity and length of US residence.

Results

In the total sample, 29.1% of women delivered preterm (31.4% and 25.6% among US born and foreign born, respectively). Compared with foreign born, US-born women were younger (25.8 vs 29.5 years), had higher prevalence of obesity (27.6% vs 19.6%), smoking (20.5% vs 4.9%), alcohol use (13.2% vs 7.4%), and moderate to severe stress (73.5% vs 59.4%) (all P < 0.001). Compared with US-born women, foreign-born women had lower odds of PTB after adjusting for sociodemographic characteristics, alcohol use, stress, parity, smoking, body mass index, chronic hypertension, and diabetes (adjusted odds ratio [aOR], 0.79; 95% confidence interval [CI], 0.65-0.97). Foreign-born NHB women with < 10 years of US residence had 43% lower odds of PTB compared with US-born (aOR, 0.57; 95% CI, 0.43-0.75), whereas those with ≥ 10 years of US residence did not differ significantly from US-born women in their odds of PTB (aOR, 0.76; 95% CI, 0.54-1.07).

Conclusions

The prevalence of CVD risk factors and proportion of women delivering preterm were lower in foreign-born than US-born NHB women. The "foreign-born advantage" was not observed with ≥ 10 years of US residence. Our study highlights the need to intensify public health efforts in exploring and addressing nativity-related disparities in PTB.

Association of grandmaternal smoking during pregnancy with DNA methylation of grandchildren: the Isle of Wight study

Background: To investigate the intergenerational effects of grandmaternal smoking during pregnancy (GMSDP) on the DNA methylation of grandchildren. Methods: Data from the Isle of Wight birth cohort with information regarding GMSDP and DNA methylation profiling at the birth of grandchildren (n = 161) were used. Differentially methylated CpG sites related to GMSDP were identified using testing-training screening, analysis of variance and multivariate analysis of covariance. The association between identified CpG sites and expression levels of neighboring genes was tested by linear regression. Results: Twenty-three CpG sites were differentially methylated in grandchildren because of GMSDP, and eight of these were associated with expression levels of 13 neighboring genes. Conclusion: GMSDP has an intergenerational effect on the DNA methylation profile of grandchildren independent of maternal smoking during pregnancy.

Perinatal Acetaminophen Exposure and Childhood Attention-Deficit/Hyperactivity Disorder (ADHD): Exploring the Role of Umbilical Cord Plasma Metabolites in Oxidative Stress Pathways

Oxidative stress mechanisms may explain associations between perinatal acetaminophen exposure and childhood attention-deficit hyperactivity disorder (ADHD). We investigated whether the changes in umbilical cord plasma amino acids needed to synthesize the antioxidant glutathione and in the oxidative stress biomarker 8-hydroxy-deoxyguanosine may explain the association between cord plasma acetaminophen and ADHD in the Boston Birth Cohort (BBC). Mother–child dyads were followed at the Boston Medical Center between 1998 and 2018. Cord plasma analytes were measured from archived samples collected at birth. Physician diagnoses of childhood ADHD were obtained from medical records. The final sample consisted of 568 participants (child mean age [SD]: 9.3 [3.5] years, 315 (52.8%) male, 248 (43.7%) ADHD, 320 (56.3%) neurotypical development). Cord unmetabolized acetaminophen was positively correlated with methionine (R = 0.33, p < 0.001), serine (R = 0.30, p < 0.001), glycine (R = 0.34, p < 0.001), and glutamate (R = 0.16, p < 0.001). Children with cord acetaminophen levels >50th percentile appeared to have higher risk of ADHD for each increase in cord 8-hydroxy-deoxyguanosine level. Adjusting for covariates, increasing cord methionine, glycine, serine, and 8-hydroxy-deoxyguanosine were associated with significantly higher odds for childhood ADHD. Cord methionine statistically mediated 22.1% (natural indirect effect logOR = 0.167, SE = 0.071, p = 0.019) and glycine mediated 22.0% (natural indirect effect logOR = 0.166, SE = 0.078, p = 0.032) of the association between cord acetaminophen >50th percentile with ADHD. Our findings provide some clues, but additional investigation into oxidative stress pathways and the association of acetaminophen exposure and childhood ADHD is warranted.

Maternal prenatal selenium levels and child risk of neurodevelopmental disorders: A prospective birth cohort study

Selenium (Se) is an essential trace element involved in various biological processes, including neurodevelopment. Available literature indicates that both Se deficiency and excess may be detrimental to health. It is also known that Se can cross the placenta from maternal to fetal circulation. To date, the role of maternal Se status in child long-term neurodevelopment is largely unexplored. This study investigated the temporal and dose-response associations between maternal Se status and child risk of neurodevelopmental disorders including autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). It consisted of 1550 mother-infant dyads from the Boston Birth Cohort. Maternal red blood cell (RBC) Se levels were measured in samples collected within 72 h of delivery (biomarker of third trimester Se status). Pediatric neurodevelopmental diagnoses were obtained from electronic medical records. Data analyses showed that maternal RBC Se levels were positively associated with child risk of developing ASD, with an adjusted odds ratio of 1.49 for ASD (95% CI: 1.09, 2.02) per IQR increase in Se. There was also a positive association between maternal Se and ADHD (OR: 1.29; 95% CI: 1.04, 1.56, per IQR increase in Se). These associations remained robust even after adjusting for pertinent covariables; and there was no significant interaction between Se and these covariables. Our findings suggest that prenatal exposure to high maternal Se levels may adversely affect child neurodevelopment. Our findings warrant further investigation; if confirmed, optimizing maternal prenatal Se levels may be necessary to maximize its health benefits while preventing undue risk.

Smoking for two- effects of tobacco consumption on placenta

Tobacco smoking is an important public health issue recognized by the world health organization as one of the most serious, preventable risk factors for developing a series of pregnancy pathologies. Maternal smoking is positively associated with intrauterine growth restriction (IUGR) and gestational diabetes (GDM), but negatively associated with preeclampsia (PE). In this review, we examine epidemiological, clinical and laboratory studies of smoking effects on immunoregulation during pregnancy, trophoblast function, and placental vasculature development and metabolism. We aim to identify effects of tobacco smoke components on specific placental compartments or cells, which may contribute to the understanding of the influences of maternal smoking on placenta function in normal and pathological pregnancies. Data corroborates that in any trimester, smoking is unsafe for pregnancy and that its detrimental effects outweigh questionable benefits. The effects of maternal smoking on the maternal immune regulation throughout pregnancy and the impact of different tobacco products on fetal growth have not yet been fully understood. Smoking cessation rather than treatment with replacement therapies is recommended for future mothers because also single components of tobacco and its smoke may have detrimental effects on placental function.

Explaining the Black-White Disparity in Preterm Birth: A Consensus Statement From a Multi-Disciplinary Scientific Work Group Convened by the March of Dimes

In 2017–2019, the March of Dimes convened a workgroup with biomedical, clinical, and epidemiologic expertise to review knowledge of the causes of the persistent Black-White disparity in preterm birth (PTB). Multiple databases were searched to identify hypothesized causes examined in peer-reviewed literature, 33 hypothesized causes were reviewed for whether they plausibly affect PTB and either occur more/less frequently and/or have a larger/smaller effect size among Black women vs. White women. While definitive proof is lacking for most potential causes, most are biologically plausible. No single downstream or midstream factor explains the disparity or its social patterning, however, many likely play limited roles, e.g., while genetic factors likely contribute to PTB, they explain at most a small fraction of the disparity. Research links most hypothesized midstream causes, including socioeconomic factors and stress, with the disparity through their influence on the hypothesized downstream factors. Socioeconomic factors alone cannot explain the disparity's social patterning. Chronic stress could affect PTB through neuroendocrine and immune mechanisms leading to inflammation and immune dysfunction, stress could alter a woman's microbiota, immune response to infection, chronic disease risks, and behaviors, and trigger epigenetic changes influencing PTB risk. As an upstream factor, racism in multiple forms has repeatedly been linked with the plausible midstream/downstream factors, including socioeconomic disadvantage, stress, and toxic exposures. Racism is the only factor identified that directly or indirectly could explain the racial disparities in the plausible midstream/downstream causes and the observed social patterning. Historical and contemporary systemic racism can explain the racial disparities in socioeconomic opportunities that differentially expose African Americans to lifelong financial stress and associated health-harming conditions. Segregation places Black women in stressful surroundings and exposes them to environmental hazards. Race-based discriminatory treatment is a pervasive stressor for Black women of all socioeconomic levels, considering both incidents and the constant vigilance needed to prepare oneself for potential incidents. Racism is a highly plausible, major upstream contributor to the Black-White disparity in PTB through multiple pathways and biological mechanisms. While much is unknown, existing knowledge and core values (equity, justice) support addressing racism in efforts to eliminate the racial disparity in PTB.

Association of Placental Pathology With Childhood Blood Pressure Among Children Born Preterm

BACKGROUND

The in utero pathologies underlying the link between preterm birth and offspring high blood pressure (BP) are still unknown. We investigated the prospective associations of placental histopathological findings with childhood BP among children born preterm.

METHODS

Our study sample included 546 mother-child pairs with preterm birth (before 37 weeks gestation) enrolled from 1999 to 2013 at the Boston Medical Center. Early preterm birth was defined as gestational age between 23 and 34 weeks. We histologically classified maternal placental pathology using the latest recommended categories: no placental complications, histologic chorioamnionitis, maternal vascular malperfusion, and other placental complications. We calculated age-, sex-, and height-specific systolic BP (SBP) percentiles for children using the 2017 American Academy of Pediatrics Clinical Practice Guideline. We used linear regression models with generalized estimating equations to examine the associations.

RESULTS

The mean (standard deviation (SD)) postnatal follow-up of the study children was 9.29 (4.1) years. After adjusting for potential confounders, histologic chorioamnionitis was associated with a 5.42 percentile higher childhood SBP (95% confidence interval: 0.32, 10.52) compared with no placental pathologic findings. This association was stronger among early preterm children. Maternal vascular malperfusion was associated with a 8.44 percentile higher childhood SBP among early preterm children (95% confidence interval: 1.54, 15.34) but the association was attenuated (6.25, 95% confidence interval: -0.76, 13.26) after additional adjustment for child standardized birthweight, a potential mediator of the association.

CONCLUSIONS

These findings suggest that among children born preterm, especially those born early preterm, both placental histologic chorioamnionitis and vascular malperfusion may help to differentiate a child's risk of high BP.

Preeclampsia Across Pregnancies and Associated Risk Factors: Findings From a High-Risk US Birth Cohort

Background

Preeclampsia increases women's risks for maternal morbidity and future cardiovascular disease. The aim of this study was to identify opportunities for prevention by examining the association between cardiometabolic risk factors and preeclampsia across 2 pregnancies among women in a high‐risk US birth cohort.

Methods and Results

Our sample included 618 women in the Boston Birth Cohort with index and subsequent pregnancy data collected using standard protocols. We conducted log‐binomial univariate regression models to examine the association between preeclampsia in the subsequent pregnancy (defined as incident or recurrent preeclampsia) and cardiometabolic risk factors (ie, obesity, hypertension, diabetes mellitus, preterm birth, low birth weight, and gestational diabetes mellitus) diagnosed before and during the index pregnancy, and between index and subsequent pregnancies. At the subsequent pregnancy, 7% (36/540) had incident preeclampsia and 42% (33/78) had recurrent preeclampsia. Compared with women without obesity, women with obesity had greater risk of incident preeclampsia (unadjusted risk ratio [RR], 2.2 [95% CI, 1.1–4.5]) and recurrent preeclampsia (unadjusted RR, 3.1 [95% CI, 1.5–6.7]). Preindex pregnancy chronic hypertension and diabetes mellitus were associated with incident, but not recurrent, preeclampsia (hypertension unadjusted RR, 7.9 [95% CI, 4.1–15.3]; diabetes mellitus unadjusted RR, 5.2 [95% CI, 2.5–11.1]. Women with new interpregnancy hypertension versus those without had a higher risk of incident and recurrent preeclampsia (incident preeclampsia unadjusted RR, 6.1 [95% CI, 2.9–13]); recurrent preeclampsia unadjusted RR, 2.4 [95% CI, 1.5–3.9]).

Conclusions

In this diverse sample of high‐risk US women, we identified modifiable and treatable risk factors, including obesity and hypertension for the prevention of preeclampsia.

Prenatal exposure to mercury and precocious puberty: a prospective birth cohort study

STUDY QUESTION

Is in utero exposure to mercury associated with the risk of precocious puberty?

SUMMARY ANSWER

Prenatal exposure to high levels of mercury was associated with increased risk of precocious puberty, which was strengthened by concomitant maternal cardiometabolic conditions and adverse birth outcomes.

WHAT IS KNOWN ALREADY

The developing fetus is sensitive to mercury, a well-known endocrine disruptor which impacts the endocrine and reproductive system.

STUDY DESIGN, SIZE, DURATION

This study included 1512 mother-child pairs from the Boston Birth Cohort, a longitudinal cohort which recruited at birth and followed prospectively up to 21 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mother-child pairs, from a predominantly urban minority population, were enrolled from 2002 to 2013. Prenatal exposure was assessed by maternal mercury concentration in red blood cells (RBCs) collected at 1-3 days after delivery. Precocious puberty was defined based on International Classification of Disease codes. Cox proportional hazards models were applied to the association between maternal mercury concentrations and the risk of precocious puberty.

MAIN RESULTS AND THE ROLE OF CHANCE

The median (interquartile range) of maternal mercury concentrations among children with and without precocious puberty were 3.4 (1.9-4.6) µg/l and 2.0 (1.0-3.7) µg/l, respectively. Compared to those in the lowest tertile for mercury, the highest tertile was associated with increased risk of precocious puberty, with an adjusted hazard ratio (HR) of 2.41, 95% CI: 1.16-5.03. In addition, concomitant maternal cardiometabolic conditions and adverse birth outcomes strengthened the effects of mercury on the risk of precocious puberty. The highest risk of precocious puberty was observed among children who had adverse birth outcomes and whose mothers had high RBC-mercury concentrations along with cardiometabolic conditions, with an HR of 4.76 (95% CI: 1.66-13.60) compared to children with favorable profiles of all three risk factors.

LIMITATIONS, REASONS FOR CAUTION

Precocious puberty was defined based on medical records, not on a direct assessment, which may have led to underdiagnosis and the inability to make a subclassification. The study included a predominately urban, low-income, minority population and as such our findings may not be widely generalizable.

WIDER IMPLICATIONS OF THE FINDINGS

Prenatal Hg exposure was associated with an increased risk of precocious puberty. This risk was strengthened by concomitant maternal cardiometabolic conditions during pregnancy and adverse birth outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the NIH/National Institute of Environmental Health Sciences, NIH/Eunice Kennedy Shriver National Institute of Child Health and Human Development and the Health Resources and Services Administration of the U.S. Department of Health and Human Services. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Genome-wide association study identifies a novel maternal gene × stress interaction associated with spontaneous preterm birth

BACKGROUND

Maternal stress is potentially a modifiable risk factor for spontaneous preterm birth (sPTB). However, epidemiologic findings on the maternal stress-sPTB relationship have been inconsistent.

METHODS

To investigate whether the maternal stress-sPTB associations may be modified by genetic susceptibility, we performed genome-wide gene × stress interaction analyses in 1490 African-American women from the Boston Birth cohort who delivered term (n = 1033) or preterm (n = 457) infants. Genotyping was performed using Illumina HumanOmni 2.5 array. Replication was performed using data from the NICHD genomic and Proteomic Network (GPN) for PTB research.

RESULTS

rs35331017, a T-allele insertion/deletion polymorphism in the protein-tyrosine phosphatase receptor Type D (PTPRD) gene, was the top hit that interacted significantly with maternal lifetime stress on risk of sPTB (P_G × E = 4.7 × 10^-8). We revealed a dose-responsive association between degree of stress and risk of sPTB in mothers carrying the insertion/insertion genotype, but an inverse association was observed in mothers carrying the heterozygous or deletion/deletion genotypes. This interaction was replicated in African-American (P_G × E = 0.088) and Caucasian mothers (P_G × E = 0.023) from the GPN study.

CONCLUSION

We demonstrated a significant maternal PTPRD × stress interaction on sPTB risk. This finding, if further confirmed, may provide new insight into individual susceptibility to stress-induced sPTB.

IMPACT

This was the first preterm study to demonstrate a significant genome-wide gene-stress interaction in African Americans, specifically, PTPRD gene variants can interact with maternal perceived stress to affect risk of spontaneous preterm birth. The PTPRD × maternal stress interaction was demonstrated in African Americans and replicated in both African Americans and Caucasians from the GPN study. Our findings highlight the importance of considering genetic susceptibility in assessing the role of maternal stress on spontaneous preterm birth.

Mediterranean-Style Diet and Birth Outcomes in an Urban, Multiethnic, and Low-Income US Population

Findings on the role of Mediterranean-style diet (MSD) on duration of pregnancy and birth weight have been inconsistent and based largely on Non-Hispanic white populations, making it unclear as to whether they could extend to African Americans who are at a higher risk of unfavorable birth outcomes. Our study addresses this gap using a large urban, multiethnic, predominantly low-income cohort of mother-infant dyads from Boston, MA, USA. Dietary information was obtained via food frequency questionnaires; health information including birth outcomes were extracted from medical records. A Mediterranean-style diet score (MSDS) was formulated based on intake history, and linear and log-binomial regressions were performed to assess its association with birth outcomes. After adjustment, the lowest MSDS quintile from the overall sample was found to be associated with an increased relative risk (RR) of overall preterm birth (RR 1.18; 95% CI: 1.06-1.31), spontaneous preterm birth (1.28; 1.11-1.49), late preterm birth (1.21; 1.05-1.39), and low birth weight (1.11; 1.01-1.22), compared to the highest quintile. The findings were similar for the African American sample. Our study adds to the current understanding of the diet's influence on birth outcomes by demonstrating that adherence to MSD may improve birth outcomes for African American women.

DNA methylation mediates the effect of maternal smoking on offspring birthweight: a birth cohort study of multi-ethnic US mother-newborn pairs

Background

Maternal smoking affects more than half a million pregnancies each year in the US and is known to result in fetal growth restriction as measured by lower birthweight and its associated long-term consequences. Maternal smoking also has been linked to altered fetal DNA methylation (DNAm). However, what remains largely unexplored is whether these DNAm alterations are merely markers of smoking exposure or if they also have implications for health outcomes. This study tested the hypothesis that fetal DNAm mediates the effect of maternal smoking on newborn birthweight.

Methods

This study included mother–newborn pairs from a US predominantly urban, low-income multi-ethnic birth cohort. DNAm in cord blood were determined using the Illumina Infinium MethylationEPIC BeadChip. After standard quality control and normalization procedures, an epigenome-wide association study (EWAS) of maternal smoking was performed using linear regression models, controlling for maternal age, education, race, parity, pre-pregnancy body mass index, alcohol consumption, gestational age, maternal pregestational/gestational diabetes, child sex, cord blood cell compositions and batch effects. To quantify the degree to which cord DNAm mediates the smoking-birthweight association, the VanderWeele-Vansteelandt approach for single mediator and structural equational model for multiple mediators were used, adjusting for pertinent covariates.

Results

The study included 954 mother–newborn pairs. Among mothers, 165 (17.3%) ever smoked before or during pregnancy. Newborns with smoking exposure had on average 258 g lower birthweight than newborns without exposure (P < 0.001). Using a false discovery rate (FDR) < 0.05 as the significance cutoff, the EWAS identified 38 differentially methylated CpG sites associated with maternal smoking. Of those, 17 CpG sites were mapped to previously reported genes: GFI1, AHRR, CYP1A1, and CNTNAP2; 8 of those, located in the first three genes, were Bonferroni significantly associated with newborn birthweight and mediated the smoking-birthweight association. The combined mediation effect of the three genes explained 67.8% of the smoking-birthweight association.

Conclusions

Our study not only lends further support that maternal smoking alters fetal DNAm in a multiethnic population, but also suggests that fetal DNAm substantially mediates the maternal smoking–birthweight association. Our findings, if further validated, indicate that DNAm modification is likely an important pathway by which maternal smoking impairs fetal growth and, perhaps, even long-term health outcomes.

Relationship of Preeclampsia With Maternal Place of Birth and Duration of Residence Among Non-Hispanic Black Women in the United States

BACKGROUND

Preeclampsia is one of the leading causes of maternal mortality in the United States. It disproportionately affects non-Hispanic Black (NHB) women, but little is known about how preeclampsia and other cardiovascular disease risk factors vary among different subpopulations of NHB women in the United States. We investigated the prevalence of preeclampsia by nativity (US born versus foreign born) and duration of US residence among NHB women.

METHODS

We analyzed cross-sectional data from the Boston Birth Cohort (1998-2016), with a focus on NHB women. We performed multivariable logistic regression to investigate associations between preeclampsia, nativity, and duration of US residence after controlling for potential confounders.

RESULTS

Of 2697 NHB women, 40.5% were foreign born. Relative to them, US-born NHB women were younger, in higher percentage current smokers, had higher prevalence of obesity (body mass index ≥30 kg/m2) and maternal stress, but lower educational level. The age-adjusted prevalence of preeclampsia was 12.4% and 9.1% among US-born and foreign-born women, respectively. When further categorized by duration of US residence, the prevalence of all studied cardiovascular disease risk factors except for diabetes was lower among foreign-born NHB women with <10 versus ≥10 years of US residence. Additionally, the odds of preeclampsia in foreign-born NHB women with duration of US residence <10 years was 37% lower than in US-born NHB women. In contrast, the odds of preeclampsia in foreign-born NHB women with duration of US residence ≥10 years was not significantly different from that of US-born NHB women after adjusting for potential confounders.

CONCLUSIONS

The prevalence of preeclampsia and other cardiovascular disease risk factors is lower in foreign-born than in US-born NHB women. The healthy immigrant effect, which typically results in health advantages for foreign-born women, appears to wane with longer duration of US residence (≥10 years). Further research is needed to better understand these associations.

Antenatal and neonatal factors contributing to extra uterine growth failure (EUGR) among preterm infants in Boston Birth Cohort (BBC)

OBJECTIVE

Identify antenatal and neonatal factors associated with primary outcome of EUGR.

METHODS

1063 preterm infants from a subset of the BBC were included in this prospective cohort study. Regression analysis was carried out to evaluate associations of EUGR with antenatal factors and neonatal factors.

RESULTS

6.1% of the infants had in-utero growth restriction (IUGR) at birth and 21.7% of infants had EUGR. The adjusted odds ratio for EUGR status were significant for birth weight (OR 0.99, p = 0.00, CI 0.99-0.99), for GA at birth (OR 4.58, p = 0.00, CI 3.25-6.44), for PDA (OR 2.9, p = 0.02, CI 1.17-7.1), for NEC (OR 5.14, p = 0.012, CI 1.44-18.3) and for day of life of reaching full feeds (OR 1.04, p = 0.001, CI 1.01-1.06).

CONCLUSION

This study highlights important factors associated with EUGR. Additional studies are needed to gain further insight.

Gaining a deeper understanding of social determinants of preterm birth by integrating multi-omics data

In the US, high rates of preterm birth (PTB) and profound Black-White disparities in PTB have persisted for decades. This review focuses on the role of social determinants of health (SDH), with an emphasis on maternal stress, in PTB disparity and biological embedding. It covers: (1) PTB disparity in US Black women and possible contributors; (2) the role of SDH, highlighting maternal stress, in the persistent racial disparity of PTB; (3) epigenetics at the interface between genes and environment; (4) the role of the genome in modifying maternal stress-PTB associations; (5) recent advances in multi-omics studies of PTB; and (6) future perspectives on integrating multi-omics with SDH to elucidate the Black-White disparity in PTB. Available studies have indicated that neither environmental exposures nor genetics alone can adequately explain the Black-White PTB disparity. Preliminary yet promising findings of epigenetic and gene-environment interaction studies underscore the value of integrating SDH with multi-omics in prospective birth cohort studies, especially among high-risk Black women. In an era of rapid advancements in biomedical sciences and technologies and a growing number of prospective birth cohort studies, we have unprecedented opportunities to advance this field and finally address the long history of health disparities in PTB. IMPACT: This review provides an overview of social determinants of health (SDH) with a focus on maternal stress and its role on Black-White disparity in preterm birth (PTB). It summarizes the available literature on the interplay of maternal stress with key biological layers (e.g., individual genome and epigenome in response to environmental stressors) and significant knowledge gaps. It offers perspectives that such knowledge may provide deeper insight into how SDH affects PTB and why some women are more vulnerable than others and underscores the critical need for integrating SDH with multi-omics in prospective birth cohort studies, especially among high-risk Black women.

A prospective cohort study on the intersectionality of obesity, chronic disease, social factors, and incident risk of COVID-19 in US low-income minority middle-age mothers

OBJECTIVE

Coronavirus disease 2019 (COVID-19) has disproportionally affected communities of color. We aimed to determine what factors are associated with COVID-19 testing and test positivity in an underrepresented, understudied, and underreported (U3) population of mothers.

METHODS

This study included 2996 middle-aged mothers of the Boston Birth Cohort (a sample of predominantly urban, low-income, Black and Hispanic mothers) who were enrolled shortly after they gave birth and followed onward at the Boston Medical Center. COVID-19 testing and test positivity were defined by the SARS-CoV-2 nucleic acid test. Two-probit Heckman selection models were performed to identify factors associated with test positivity while accounting for potential selection associated with COVID testing.

RESULTS

The mean (SD) age of study mothers was 41.9 (±7.7) years. In the sample, 1741 (58.1%) and 667 (22.3%) mothers were self-identified as Black and Hispanic, respectively. A total of 396 mothers had COVID-19 testing and of those, 95 mothers tested positive from March 2020 to February 2021. Among a multitude of factors examined, factors associated with the probability of being tested were obesity (RR = 1.27; 95% confidence interval (CI): 1.08-1.49); and presence of preexisting chronic medical conditions including hypertension, asthma, stroke, and other comorbidities (coronary heart disease, chronic kidney disease, and sickle cell disease) with a corresponding RR = 1.40 (95% CI: 1.23-1.60); 1.29 (95% CI: 1.11-1.50); 1.44 (95% CI: 1.23-1.68); and 1.37 (95% CI: 1.12-1.67), respectively. Factors associated with higher incident risk of a positive COVID-19 test were body mass index, birthplace outside of the USA, and being without a college-level education.

CONCLUSIONS

This study demonstrated the intersectionality of obesity and social factors in modulating incident risk of COVID-19 in this sample of US Black and Hispanic middle-aged mothers. Methodologically, our findings underscore the importance of accounting for potential selection bias in COVID-19 testing in order to obtain unbiased estimates of COVID-19 infection.

Joint Associations of Maternal-Fetal APOL1 Genotypes and Maternal Country of Origin With Preeclampsia Risk

RATIONALE & OBJECTIVES

Preeclampsia, which disproportionately affects Black women, is a leading cause of preterm delivery and risk for future hypertension and chronic kidney disease (CKD). Apolipoprotein L1 (APOL1) kidney risk alleles, common among Black individuals, contribute substantially to CKD disparities. Given the strong link between preeclampsia and CKD, we investigated whether maternal and fetal APOL1 risk alleles can jointly influence preeclampsia risk, and explored potential modifiers of the association between APOL1 and preeclampsia.

STUDY DESIGN

Nested case-control study.

SETTING & PARTICIPANTS

426 Black mother-infant pairs (275 African Americans and 151 Haitians) from the Boston Birth Cohort.

EXPOSURE

Maternal and fetal APOL1 risk alleles.

OUTCOMES

Preeclampsia.

ANALYTICAL APPROACH

Logistic regression models with adjustment for demographic characteristics were applied to analyze associations between fetal and maternal APOL1 risk alleles and risk of preeclampsia and to investigate the effects of modification by maternal country of origin.

RESULTS

Fetal APOL1 risk alleles tended to be associated with an increased risk of preeclampsia, which was not statistically significant in the total genotyped population. However, this association was modified by maternal country of origin (P<0.05 for interaction tests): fetal APOL1 risk alleles were significantly associated with an increased risk of preeclampsia among African Americans under recessive (odds ratio [OR], 3.6 [95% CI, 1.3-9.7]; P=0.01) and additive (OR, 1.7 [95% CI, 1.1-2.6]; P=0.01) genetic models but not in Haitian Americans. Also, maternal-fetal genotype discordance at the APOL1 locus was associated with a 2.6-fold higher risk of preeclampsia (P<0.001) in African Americans.

LIMITATIONS

Limited sample size in stratified analyses; self-reported maternal country of origin; pre-pregnancy estimated glomerular filtration rate (eGFR) and proteinuria data in mothers were not collected; unmeasured confounding social and/or environmental factors; no replication study.

CONCLUSIONS

This study supports the hypothesis that fetal APOL1 kidney risk alleles are associated with increased risk for preeclampsia in a recessive mode of inheritance in African Americans and suggests that maternal-fetal genotype discordance is also associated with this risk. These conclusions underscore the need to better understand maternal-fetal interaction and their genetic and environmental factors as contributors to ethnic disparities in preeclampsia.