Characterization of maternal plasma biomarkers associated with delivery of small and large for gestational age infants in the MIREC study cohort

A cohort study of the multipollutant effects of PM2.5, NO2, and O3 on C-reactive protein levels during pregnancy

Background

PM2.5, NO2, and O3 contribute to the development of adverse pregnancy complications. While studies have investigated the independent effects of these exposures, literature on their combined effects is limited. Our objective was to study the multipollutant effects of PM2.5, NO2, and O3 on maternal systemic C-reactive protein (CRP) levels.

Methods

We used data from 1170 pregnant women enrolled in the Maternal-Infant Research on Environmental Chemicals Study (MIREC) study in Canada. Air pollution exposures were assigned to each participant based on residential location. CRP was measured in third-trimester blood samples. We fit multipollutant linear regression models and evaluated the effects of air pollutant mixtures (14-day averages) using repeated-holdout Weighted Quantile Sum (WQS) regression and by calculating the Air Quality Health Index (AQHI).

Results

In multipollutant models adjusting for NO2, O3, and green space, each interquartile range (IQR) increase in 14-day average PM2.5 (IQR: 6.9 µg/m3) was associated with 27.1% (95% confidence interval [CI] = 6.2, 50.7) higher CRP. In air pollution mixture models adjusting for green space, each IQR increase in AQHI was associated with 37.7% (95% CI = 13.9, 66.5) higher CRP; and an IQR increase in the WQS index was associated with 78.6% (95% CI = 29.7, 146.0) higher CRP.

Conclusion

PM2.5 has the strongest relationship of the individual pollutants examined with maternal blood CRP concentrations. Mixtures incorporating all three pollutants, assessed using the AQHI and WQS index, showed stronger relationships with CRP compared with individual pollutants and illustrate the importance of conducting multipollutant analyses.

Exposure to gestational diabetes mellitus increases subclinical inflammation mediated in part by obesity

Gestational diabetes mellitus (GDM) is a frequent and serious complication of pregnancy, often associated with obesity. Metabolic dysfunction and metainflammation are evident in both obesity and GDM. In this cross-sectional study, we aimed at defining the direct contribution of the immune system in GDM, across the main metabolic tissues, specifically focussing on elucidating the roles of obesity and GDM to the clinical outcome. Using immunoassays and multicolour flow cytometry, cytokine profiles and immune cell frequencies were measured in maternal circulation and central metabolic tissues [placenta and visceral adipose tissue (VAT)] in GDM-diagnosed (n = 28) and normal glucose tolerant (n = 32) women undergoing caesarean section. Participants were sub-grouped as non-obese [body mass index (BMI) < 30 kg/m2] or obese (BMI ≥ 30 kg/m2). Unsupervised data analysis was performed on the flow cytometry data set to identify functional alterations. GDM obese participants had significantly elevated circulating IL-6 and IL-17A levels. GDM non-obese participants had elevated circulating IL-12p70, elevated placental IL-17A, and VAT IFN-γ production. Unsupervised clustering of immune populations across the three biological sites simultaneously, identified different NK- and T-cell phenotypes that were altered in NGT obese and GDM non-obese participants, while a classical tissue monocyte cluster was increased in GDM obese participants. In this study, there was significant evidence of subclinical inflammation, and significant alterations in clusters of NK cells, T cells, and tissue monocyte populations in GDM. While increased adiposity assimilates with increased inflammation in the non-pregnant state, this overt relationship may not be as evident during pregnancy and warrants further examination in future longitudinal studies.

Prenatal exposure to perfluoroalkyl substances and inflammatory biomarker concentrations

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that induce immunotoxicity in experimental studies; however, epidemiological evidence-particularly during pregnancy-is scarce. We quantified associations between first trimester plasma perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) concentrations and third trimester concentrations of inflammatory biomarkers and determined if these associations were modified by fetal sex.

Methods

We analyzed data from 1411 participants, recruited between 2008 and 2011, in the Maternal-Infant Research on Environmental Chemicals study. Our primary outcome was a composite inflammatory index derived by summing the z-scores of eight proinflammatory biomarkers. Using multivariable linear regression models, we quantified associations between each PFAS and the inflammatory index and individual biomarkers. We quantified the effects of the PFAS mixture using weighted quantile sum regression, and evaluated effect modification using product terms and sex-stratified models.

Results

Each doubling of PFOA and PFHxS was associated with a 0.38 (95% CI, 0.09, 0.67) and 0.21 (95% CI, 0.01, 0.41) SD increase in the proinflammatory index, respectively. A one-quartile increase in the PFAS mixture was associated with a 0.40 (95% CI, 0.09, 0.71) SD increase in the proinflammatory index. In individual models, we observed positive associations between PFAS and concentrations of monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and matrix metalloproteinases-9; however, the magnitude and precision varied according to the specific PFAS. Sex-specific findings were identified in few PFAS-biomarker associations.

Conclusions

PFOA, PFOS, and PFHxS, individually and as a mixture, were positively associated with proinflammatory biomarkers during pregnancy.

Impact of Maternal Monocyte to High-density Lipoprotein Cholesterol Ratio on the Incidence of Large-for-gestational-age Newborns: An Observational Cohort Study

BACKGROUND AND OBJECTIVES

Monocyte to high-density lipoprotein cholesterol ratio (MHR) has recently been identified as a new marker of inflammation and oxidative stress. However, it is unknown whether maternal MHR is associated with fetal weight at birth. Therefore, our objective was to analyze the association between maternal MHR and the frequency of small/large for gestational age (SGA/LGA) newborns in this retrospective cohort study.

METHODS

We retrospectively analyzed hospitalization records and laboratory data and obtained results from consecutive pregnant women in whom the blood lipid level had been investigated along with the blood cell count. Linear regression and logistic regression analyses were performed to estimate the associations of maternal MHR with birth weight and SGA/LGA.

RESULTS

Monocyte counts and MHR were positively associated with birth weight/LGA risk (monocyte [1-109/L increase] for birth weight: β: 170.24, 95% confidence interval [CI]: 41.72-298.76, LGA: odds ratio [OR]: 7.67; 95% CI: 2.56-22.98; MHR [1-109/mmol increase] for birth weight: β: 294.84, 95% CI: 170.23-419.44, LGA: OR: 7.97; 95% CI: 3.06-20.70), whereas high-density lipoprotein cholesterol (HDL-C) levels were negatively associated with birth weight/LGA risk [1 mmol/L increase for birth weight (β: -99.83, 95% CI: -130.47 to -69.19), for LGA: (OR: 0.57, 95% CI: 0.45-0.73). Obese pregnant women (body mass index [BMI] ≥30 kg/m2) with higher MHR (tertile 3: >0.33 109/mmol) significantly increased LGA risk by 6.39 fold (95% CI: 4.81, 8.49) compared to those with low MHR (tertile 1-2: ≤0.33 109/mmol) and normal weight (BMI <25 kg/m2).

CONCLUSION

Maternal MHR is associated with LGA risk, and this association might be further modified by BMI.

Joint associations among prenatal metal mixtures and nutritional factors on birth weight z-score: Evidence from an urban U.S. population

The benefits of nutritional factors on birth outcomes have been recognized, however, limited studies have examined the role of nutritional factors in mitigating the detrimental effects of metals exposure during gestation. We used data collected from 526 mother-infant dyads enrolled in the Programming of Intergenerational Stress Mechanisms longitudinal pregnancy cohort to examine the joint effects of prenatal exposure to metals and maternal nutrition on birth weight for gestational age (BWGA) z-scores. We measured concentrations of twelve metals and trace elements in urine samples collected during pregnancy. Maternal nutritional intake was measured using the Block98 Food Frequency Questionnaire and converted into energy-adjusted consumption of individual nutrients. Using multivariable linear regression and Bayesian Kernel Machine Regression, we found that three metals [cobalt (Co), nickel (Ni), and lead (Pb)] and five metals [barium (Ba), caesium (Cs), copper (Cu), Ni, and zinc (Zn)] were associated with BWGA z-score in male and female infants, respectively. When examining the sex-specific interactions between these metals and nutrient groups [macro nutrients, minerals, A vitamins, B vitamins, anti-oxidant, methyl-donor nutrients, and inflammatory (pro- and anti-)] using a Cross-validated Kernel Ensemble model, we identified significant interactions between the macro nutrients and Co (p = 0.05), minerals and Pb (p = 0.04), and A vitamins and Ni (p = 0.001) in males. No significant interactions were found in females. Furthermore, three minerals (phosphorus, iron, potassium) and vitamin A were found to be more crucial than other nutrients in modifying the association between each respective metal and BWGA z-score in males. A better understanding of the sex-specific interactions between nutrients and metals on birth weight can guide pregnant women to protect their neonates from the adverse health impacts of metal exposures by optimizing nutrient intakes accordingly.

Plasma cytokines during pregnancy provide insight into the risk of diabetes in the gestational diabetes risk group

Aims/Introduction

Gestational diabetes (GDM) is characterized by low‐grade systemic inflammation, which manifests as changes in the levels of cytokines in the blood. We aimed to investigate plasma immune mediators during gestational weeks 23–28 in 213 women at risk for GDM, and to find associations between GDM and its complications.

Materials and Methods

We quantified the levels of adipokines: adiponectin, leptin, plasminogen activator inhibitor‐1 and resistin; chemokines: C‐C motif chemokine ligand 2 (CCL2), CCL4, C‐X‐C motif chemokine ligand 8 (CXCL8) and CXCL10; and cytokines: granulocyte‐macrophage colony‐stimulating factor, interferon‐γ, interleukin (IL)‐1β, soluble (s)IL‐1RI, IL‐2, sIL‐2Ra, IL‐4, IL‐5, IL‐6, IL‐7, IL‐10, IL‐12(p70), IL‐13, IL‐15, IL‐17A, IL‐17F, IL‐21, IL‐22, IL‐23, IL‐27, transforming growth factor (TGF)‐β1, TGF‐β2, TGF‐β3, tumor necrosis factor‐α and soluble tumor necrosis factor receptor 2 using the Milliplex®MAP Magnetic Bead assay on Luminex®200™, and compared the results with clinical data from pregnancy and post‐partum follow up.

Results

Lower levels of adiponectin and higher levels of CCL2 (Wilcoxon test, P = 3.4E‐03 and P = 0.03, respectively) were found in women with GDM. IL‐27 levels were associated with lower odds of GDM (adjusted logistic regression 0.90, P = 2.4E‐03), and showed a risk association with glutamic acid decarboxylase autoantibody positivity (adjusted odds ratio 1.13, P = 2.8E‐03). Similarly, higher IL‐22 levels increased the odds of glutamic acid decarboxylase autoantibody positivity (adjusted odds ratio 4.23, P = 0.04). TGF‐β1 was associated with post‐partum fasting glucose levels, and CCL4 with post‐partum C‐peptide levels (linear regression, P = 0.04 and P = 0.01, respectively). Women who developed pregnancy complications had higher levels of CXCL10 and CCL4 (linear regression, P = 7.0E‐04 and P = 0.01, respectively).

Conclusions

Plasma adiponectin and CCL2 concentrations distinguish women with GDM. IL‐27 and IL‐22 levels might select women with an autoimmune reaction, whereas increased TGF‐β1 and CCL4 are associated with post‐partum glucose and insulin metabolism.

Longitudinal changes in serum immune markers during normal pregnancy in a North-Indian population

PROBLEM

The objective of this study was to examine levels of cytokines across normal term pregnancy in an Indian population. Additionally we have also explored for possible associations between inflammatory markers and fetal growth parameters.

METHOD OF STUDY

A multiplex panel of 24 analytes was used to examine levels of inflammatory markers in maternal serum at three time points during pregnancy and in cord blood from women with no reported comorbidities who delivered a singleton live baby at term (N = 23), enrolled in the GARBH-Ini pregnancy cohort. Linear mixed models were applied to construct longitudinal cytokine trajectories with gestational age. Pearson correlation was used to calculate intra-visit correlation between cytokines. Principal component analysis (PCA) was performed to examine cytokine combinations prevalent across pregnancy, and their association with fetal growth parameters was determined by multivariable regression.

RESULTS

Significant increase in sFLT-1, Flt3L, PLGF, IL-4, and IL-18 and a decrease in VCAM-1 concentrations was seen across pregnancy. The cytokine concentrations in cord blood differed substantially as compared to maternal levels across gestation. Some cytokines were closely correlated with each other in distinct patterns across pregnancy. Gestational age specific combination of cytokines were seen to be associated with different fetal growth parameters.

CONCLUSIONS

This study for the first time provides reference concentrations for the longitudinal expression of immune markers across pregnancy in an Indian population providing a much needed baseline to compare with pregnancies leading to adverse outcomes. Growth factors showed maximum longitudinal variation with gestational age and strong correlations were identified between various cytokines at all time points across pregnancy.

Ambient air pollution and inflammatory effects in a Canadian pregnancy cohort

Supplemental Digital Content is available in the text.

Background:

Epidemiologic studies have consistently reported associations between air pollution and pregnancy outcomes including preeclampsia and gestational diabetes. However, the biologic mechanisms underlying these relationships remain unclear as few studies have collected relevant biomarker data. We examined relationships between ambient PM_2.5 and NO₂ with markers of inflammation during pregnancy in a prospective cohort of Canadian women.

Methods:

We analyzed data from 1170 women enrolled in the Maternal-Infant Research on Environmental Chemicals study. Daily residential PM_2.5 and NO₂ exposures during pregnancy were estimated using satellite-based and land-use regression models and used to create 14-day and 30-day exposure windows before blood-draw. Inflammatory markers C-reactive protein, interleukin-6, interleukin-8, and tumor necrosis factor-α were measured in third trimester plasma samples. Multivariable linear regression was used to estimate associations for an interquartile range (IQR) increase in PM_2.5 and NO₂ and markers of inflammation, while adjusting for individual-level confounders.

Results:

Fourteen-day (IQR: 6.85 µg/m³) and 30-day (IQR: 6.15 µg/m³) average PM_2.5 exposures before blood-draw were positively associated with C-reactive protein after adjustment for covariates (24.6% [95% CI = 9.4, 41.9] and 17.4% [95% CI = 1.0, 35.0] increases, respectively). This association was found to be robust in several sensitivity analyses. Neither PM_2.5 nor NO₂ exposures were associated with interleukin-6, interleukin-8, or tumor necrosis factor-α.

Conclusion:

Exposure to ambient PM_2.5 is positively associated with maternal inflammatory pathways in late pregnancy. This may contribute to positive associations between ambient PM_2.5 and risk of adverse pregnancy outcomes.

Adverse pregnancy outcomes among mothers with hypertensive disorders in pregnancy: A meta-analysis of cohort studies

BACKGROUND

Presently, the results of studies assessing the association of hypertensive disorders in pregnancy (HDP) with adverse pregnancy outcomes (APOs) in offspring remain inconclusive, and a complete overview is missing. We performed a meta-analysis of cohort studies to review and summarize the association between HDP and risk of APOs in offspring.

METHODS

PubMed, Embase, Web of Science and Chinese databases were searched through May 2019 to identify eligible studies. Outcomes of interest were APOs including perinatal death, fetal death, stillbirth, neonatal death, congenital malformations, preterm birth (PTB), very preterm birth (VPTB), intrauterine growth restriction (IUGR), small for gestational age (SGA), low birth weight (LBW), and very low birth weight (VLBW). Either a fixed- or a random-effects model was used to calculate the overall combined risk estimates. Subgroup analysis was performed to explore potential heterogeneity moderators.

RESULTS

Total 152 cohort studies involving 1,426,742 mothers with HDP and 36,374,542 mothers without HDP were included for analysis. Overall, mothers with HDP compared with those without HDP had a significantly higher risk of perinatal death (OR = 2.86), fetal death (OR = 2.82), stillbirth (OR = 1.93), neonatal death (OR = 1.55), congenital malformations (OR = 2.66), IUGR (OR = 5.48), SGA (OR = 3.39), LBW (OR = 5.02), VLBW (OR = 1.74), PTB (OR = 4.20) and VPTB (OR = 3.26) in offspring. Relevant heterogeneity moderators were identified by subgroup analyses. The sensitivity analysis yielded consistent results. No evidence of publication bias was observed.

CONCLUSION

The present study indicates that HDP significantly increases risk of APOs. Further research is needed to explore efficient management methods to minimize the risk of APOs associated with HDP.

Does Low Maternal Exposure to Per- and Polyfluoroalkyl Substances Elevate the Risk of Spontaneous Preterm Birth? A Nested Case-Control Study in China

Previous animal and human studies suggest potential links between maternal exposure to per- and polyfluoroalkyl substances (PFASs) and adverse birth outcomes. As spontaneous preterm birth (SPB) represents a major cause of infant mortality and precursor to future morbidity, we conducted a prospective nested case-control study in Shanxi Province, China to investigate the association between prenatal PFAS exposure and SPB risk, as well as the associations with biomarkers of oxidative stress and systemic inflammation. Among 4229 women enrolled during 2009-2013, 144 SPB cases and 375 controls were included in this study. Seventeen PFASs, as well as monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), and heme oxygenase-1 (HO-1), were measured in maternal plasma or serum collected during 4th-22nd gestational weeks. Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and its alternative chlorinated polyfluoroether sulfonic acid (6:2 Cl-PFESA) were detected in more than 90% samples with a median concentration of 0.79, 1.79, and 0.34 ng/mL, respectively. The analyses revealed no significant associations between plasma PFASs and the SPB risk after adjusting for potential confounders. However, concentrations of PFOS and 6:2 Cl-PFESA were both significantly and positively associated with MCP-1 levels, while PFOA was inversely associated with IL-8. Our findings suggested that maternal exposure to the determined low levels of PFAS did not induce an elevated risk of SPB, but the exposure may disturb potential biochemical pathways of inflammation. The latter has important implications for possible birth outcome effects and developmental effects in fetuses and newborns, which warrants close attention.

Diet as a counteracting agent of the effect of some well-known risk factors for small for gestational age

OBJECTIVE

The aim of this study was to assess whether diet variables can neutralize the risk produced by three well-known risk factors for being small for gestational age: smoking, body mass index (BMI) ˂20 kg/m², and having a previous preterm/low birth weight (LBW) newborn.

METHODS

A matched case control study was conducted (518 cases and 518 controls of pregnant women) in Spain. We collected data on demographic characteristics, socioeconomic status, toxic habits, and diet. Dietary intake during pregnancy was assessed using a validated food frequency questionnaire, categorized into quintiles. Adjusted odds ratios (aORs) and their 95% confidence intervals (CI) were estimated by conditional regression logistic models.

RESULTS

Women who smoked during pregnancy had a 78% increased risk for having an SGA newborn (aOR, 1.78; 95% CI, 1.28-2.74). Lean women (BMI ˂ 20 kg/m² before pregnancy) augmented the risk 139% (aOR, 2.39; 95% CI, 1.68-3.40), and those with a previous SGA-LBW an increase of 160% (aOR, 2.60; 95% CI, 1.53-4.37). Smoking in women with a fruit intake of ≥421 g/d was not associated with a higher risk for SGA versus non-smoking women with the same fruit intake (aOR, 0.98; 95% CI, 0.41-2.33). A BMI <20 kg/m² with an intake of ≥33 g/d of legumes did not increase the risk for SGA versus women with a BMI ≥20 kg/m² with the same legume intake (aOR, 1.35; 95% CI, 0.54-3.37). Diet did not modify the risk by having a previous SGA-LBW newborn.

CONCLUSIONS

Smoking and leanness increased the SGA risk; nevertheless foods such as fruit, fish, and legumes, as well as intake of vitamins D and B₃ and ω-3 marine fatty acids, may "at" least partially counteract this increase.

Pro-inflammatory immune cell gene expression during the third trimester of pregnancy is associated with shorter gestational length and lower birthweight

PROBLEM

Altered maternal immune function predicts risk for shorter gestation and low birthweight. Few studies examine associations between prenatal immune cell gene expression and gestational length or birthweight. No studies examine which cell types drive associations. The purpose of this study is to explore associations between peripheral blood immune cell gene expression and gestational length and birthweight, using transcript origin analysis.

METHOD OF STUDY

Eighty-nine women were drawn from the Community Child Health Network cohort. Third trimester maternal dried blood spots were used for genome-wide transcriptional (mRNA) profiling. Gestational length and birthweight were obtained from medical charts. Covariates were age, race/ethnicity, pre-pregnancy body mass index, smoking, gestational age at blood sampling, and pregnancy infections. Associations between gene expression profiles and gestational length and birthweight were tested using general linear models. The Transcription Element Listening System (TELiS) bioinformatics analysis quantified upstream transcription factor activity. Transcript origin analysis identified leukocyte subsets mediating observed effects.

RESULTS

Shorter gestation was predicted by increased NF-kB (TFBM ratio = -0.582 ± 0.172, P < .001) and monocyte activity (diagnosticity score = 0.172 ± 0.054, P < .001). Longer gestation was associated with increased dendritic cell activity (diagnosticity score = 0.194 ± 0.039, P < .001). Increased AP-1 activity predicted lower birthweight (TFBM ratio = -0.240 ± 0.111, P = .031). Dendritic cells and CD4+ and CD8+ T cells predicted birthweight-related gene expression differences (diagnosticity score P's < 0.021).

CONCLUSION

Higher third trimester pro-inflammatory gene expression predicted shorter gestation and lower birthweight. Variations in monocyte and dendritic cell biology contributed to both effects, and T-cell biology contributed to higher birthweight. These analyses clarify the role of myeloid/lymphoid lineage immune regulation in pregnancy outcomes.

Fetal Growth Restriction Prediction: How to Move beyond

The actual burden and future burden of the small-for-gestational-age (SGA) babies turn their screening in pregnancy a question of major concern for clinicians and policymakers. Half of stillbirths are due to growth restriction in utero, and possibly, a quarter of livebirths of low- and middle-income countries are SGA. Growing body of evidence shows their higher risk of adverse outcomes at any period of life, including increased rates of neurologic delay, noncommunicable chronic diseases (central obesity and metabolic syndrome), and mortality. Although there is no consensus regarding its definition, birthweight centile threshold, or follow-up, we believe birthweight <10th centile is the most suitable cutoff for clinical and epidemiological purposes. Maternal clinical factors have modest predictive accuracy; being born SGA appears to be of transgenerational heredity. Addition of ultrasound parameters improves prediction models, especially using estimated fetal weight and abdominal circumference in the 3rd trimester of pregnancy. Placental growth factor levels are decreased in SGA pregnancies, and it is the most promising biomarker in differentiating angiogenesis-related SGA from other causes. Unfortunately, however, only few societies recommend universal screening. SGA evaluation is the first step of a multidimensional approach, which includes adequate management and long-term follow-up of these newborns. Apart from only meliorating perinatal outcomes, we hypothesize SGA screening is a key for socioeconomic progress.