Maternal smoking and preterm birth: An unresolved health challenge

Maternal smoking DNA methylation risk score associated with health outcomes in offspring of European and South Asian ancestry

Background

Maternal smoking has been linked to adverse health outcomes in newborns but the extent to which it impacts newborn health has not been quantified through an aggregated cord blood DNA methylation (DNAm) score. Here, we examine the feasibility of using cord blood DNAm scores leveraging large external studies as discovery samples to capture the epigenetic signature of maternal smoking and its influence on newborns in White European and South Asian populations.

Methods

We first examined the association between individual CpGs and cigarette smoking during pregnancy, and smoking exposure in two White European birth cohorts (n=744). Leveraging established CpGs for maternal smoking, we constructed a cord blood epigenetic score of maternal smoking that was validated in one of the European-origin cohorts (n=347). This score was then tested for association with smoking status, secondary smoking exposure during pregnancy, and health outcomes in offspring measured after birth in an independent White European (n=397) and a South Asian birth cohort (n=504).

Results

Several previously reported genes for maternal smoking were supported, with the strongest and most consistent association signal from the GFI1 gene (6 CpGs with p<5 × 10-5). The epigenetic maternal smoking score was strongly associated with smoking status during pregnancy (OR = 1.09 [1.07, 1.10], p=5.5 × 10-33) and more hours of self-reported smoking exposure per week (1.93 [1.27, 2.58], p=7.8 × 10-9) in White Europeans. However, it was not associated with self-reported exposure (p>0.05) among South Asians, likely due to a lack of smoking in this group. The same score was consistently associated with a smaller birth size (-0.37±0.12 cm, p=0.0023) in the South Asian cohort and a lower birth weight (-0.043±0.013 kg, p=0.0011) in the combined cohorts.

Conclusions

This cord blood epigenetic score can help identify babies exposed to maternal smoking and assess its long-term impact on growth. Notably, these results indicate a consistent association between the DNAm signature of maternal smoking and a small body size and low birth weight in newborns, in both White European mothers who exhibited some amount of smoking and in South Asian mothers who themselves were not active smokers.

Funding

This study was funded by the Canadian Institutes of Health Research Metabolomics Team Grant: MWG-146332.

Effects of psychosocial work factors on preterm birth: systematic review and meta-analysis

OBJECTIVES

Preterm birth is one of the global public health issues that result in high rates of infant mortality and long-term health complications. We sought to explore the association between psychosocial work factors and preterm birth.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

This systematic review and meta-analysis searched relevant literature from electronic databases to explore the association between psychosocial work factors and preterm birth. The methodological quality of the included studies was evaluated through the Joanna Briggs Institute's critical appraisal method. We performed a meta-analysis using a random-effects model to combine odds ratios (ORs) from studies with similar definitions of exposure and outcome. The quality of the evidence was evaluated using the GRADE (Grade of recommendation, Assessment, development, and Evaluation) method to assess.

RESULTS

Ten studies were included, with a total of 92,815 participants. Moderate evidence indicated a positive association between high psychosocial job strain and preterm birth. The result from the meta-analysis supported the statistical significance of this relationship (OR 1.32 [95% CI (1.22-1.44)]).

CONCLUSIONS

Pregnant women who experience high levels of psychosocial job strain are more likely to give birth prematurely. In order to decrease this risk, employers should prioritise creating supportive work environments, government bodies should enact protective policies and regulations, and clinicians should give advice to pregnant working women. Pregnant women should be aware of the risk of preterm birth from psychosocial work factors.

Parental smoking in the first two years of a child's life and its associations with breastfeeding

BACKGROUND

Exclusive breastfeeding for the first 6 months followed by ongoing breastfeeding to 12 months and beyond is associated with multiple benefits for both mother and child. Maternal smoking is associated with a reduction in breastfeeding. Little is known about the effect of partner smoking on breastfeeding.

AIMS

This study explores the smoking behaviour of mothers and their partners in the first two years of a child's life and its associations with breastfeeding practice.

MATERIALS AND METHODS

We performed a secondary data analysis using survey data on 1155 mothers from their third trimester of pregnancy and at six, 12 and 24 months after delivery. Survey questions included smoking status of both mother and partner and breastfeeding intention and practice. Logistic regression models were conducted at each time point.

FINDINGS

Where the mother or both parents smoke, babies were less likely to be breastfed at six months of age (adjusted odds ratio (aOR) 0.29, 95% CI: 0.13-0.66) compared with families where neither parent smoked. Non-smoking mothers with smoking partners were less likely to intend to breastfeed (aOR 0.29, 95% CI: 0.11-0.82) and their babies were less likely to be breastfed at six and 12 months of age (aOR 0.64, 95% CI: 0.42-0.98 and 0.64, 95% CI: 0.43-0.95 respectively). There was no difference in breastfeeding behaviour between smoking and non-smoking parents at 24 months.

CONCLUSION

Smoking parents are less likely to breastfeed their babies at ages six and 12 months. Breastfeeding promotion should target both smoking mothers and smoking partners.

The association between adverse birth outcomes and smoking cessation during pregnancy across the United States-43 States and New York City, 2012-2017

PURPOSE

This cross-sectional study aimed to estimate the risks of adverse birth outcomes among pregnant smokers and the benefits of smoking cessation during pregnancy on birth outcomes across the United States.

METHODS

We performed an analysis of 203,437 pregnant women using data collected by the Pregnancy Risk Assessment Monitoring System (PRAMS) from 2012 to 2017. PRAMS uses questionnaires and birth certificates to collect information about the socio-demographic characteristics of pregnant women, smoking status before and during pregnancy, and birth outcomes. We assessed the relationship between self-reported smoking status during pregnancy and preterm birth, low birth weight, and small-for-gestational-age using multivariable logistic regression models.

RESULTS

In our study population, 80.43% of pregnant women never smoked, 10.55% of pregnant women quit smoking during pregnancy, and 9.02% continued smoking during pregnancy. Puerto Rico had the highest prevalence of non-smokers (94.12%), while West Virginia had the lowest prevalence of non-smokers (60.54%). Pregnant women who had a higher education level, were married, had less than 5 types of stress, and had government or private insurance before pregnancy had a higher prevalence of smokers who quit during pregnancy (quit smokers) than those that continued smoking (continuous smokers). Compared to non-smokers, continuous smokers had a significantly higher risk of low birth weight (AOR: 1.91, 95% CI 1.80, 2.03), preterm birth (AOR: 1.31, 95% CI 1.21, 1.41), and small-for-gestational-age (AOR: 2.22, 95% CI 2.07, 2.39). However, the relationships between quitting smoking and preterm birth and small-for-gestational-age were not significant.

CONCLUSION

Our models suggest that smoking cessation during pregnancy can prevent adverse birth outcomes by significantly reducing the risk of preterm birth and small-for-gestational-age to almost comparable to not smoking.

Prenatal tobacco smoke exposure and risk of brain abnormalities on magnetic resonance imaging at term in infants born very preterm

BACKGROUND

Prenatal tobacco smoke exposure and preterm birth are associated with abnormal brain and neurodevelopmental outcomes in infants. Studies that can disentangle indirect mediating effects from direct effects of prenatal tobacco smoke exposure on sensitive early brain magnetic resonance imaging biomarkers in very preterm infants are needed.

OBJECTIVE

This study aimed to determine whether prenatal tobacco smoke exposure in preterm infants posed any direct effects on magnetic resonance imaging-determined global brain abnormality score and secondary measures of brain abnormalities after removing any indirect mediating effects of preterm birth on neurostructural outcomes.

STUDY DESIGN

We examined brain magnetic resonance imaging findings collected at 39 to 44 weeks postmenstrual age from a prospective cohort of 395 infants born very preterm (gestational age of ≤32 weeks). The primary outcome was global brain abnormality score, and the secondary outcomes were global efficiency of structural connectome, diffuse white matter abnormality volume, total brain tissue volume, total gray and white matter volumes, and cerebellar volume. Maternal reports of smoking during pregnancy were obtained. We performed multivariable linear regression analyses to examine the association between prenatal tobacco smoke exposure and our magnetic resonance imaging outcomes, controlling for prospectively collected confounders. Moreover, we performed a mediation analysis to estimate the direct effects of prenatal tobacco smoke exposure on brain abnormalities and any indirect effects through preterm birth.

RESULTS

Overall, 12.6% of infants had prenatal tobacco smoke exposure. Infants with prenatal tobacco smoke exposure had a higher median global brain abnormality score than nonexposed infants (7 [interquartile range, 0-41] vs 5 [interquartile range, 0-34]; P≤.001); the findings remained significant (P<.001) after controlling for antenatal confounders. Global efficiency (P<.001), diffuse white matter volume (P=.037), and total brain tissue volume (P=.047) were significantly different between TSE groups in multivariable analyses. On mediation analysis, preterm birth mediated between 0% and 29% of the indirect effect of prenatal tobacco smoke exposure on several measures of brain abnormality outcomes. Thus, prenatal tobacco smoke exposure had a direct adverse effect between 71% and 100% on brain injury or abnormal development.

CONCLUSION

Our study has identified multiple adverse effects of prenatal tobacco smoke exposure on sensitive and objective measures of neonatal brain injury and abnormal development; most cases seemed to be a direct effect of prenatal tobacco smoke exposure on fetal brain development. The results underscored the significant adverse neurostructural effects of prenatal tobacco smoke exposure to tobacco smoke pollutants.

Comparing maternal substance use and perinatal outcomes before and during the COVID-19 pandemic

OBJECTIVE

To examine the effect of the COVID-19 pandemic on maternal substance abuse and neonatal outcomes.

STUDY DESIGN

Cross-sectional observational study of neonates admitted to the NICU and born to mothers with evidence of substance abuse pre-pandemic compared to during the COVID-19 pandemic.

RESULT

We noted a significant increase in fentanyl (12% vs. 0.6%, p < 0.001) and tobacco use (64% vs. 33%, p < 0.001) during the pandemic compared to pre-pandemic, including an increase in fentanyl use among mothers enrolled in opioid maintenance therapy (OMT) during the pandemic (32.3% vs. 1.5%, p < 0.001). There was a significant increase in preterm births (58% vs. 48%, p = 0.022) and lower birth weight (2315 ± 815 vs. 2455 ± 861 g, p = 0.049) during pandemic.

CONCLUSION

There was a significant increase in maternal fentanyl use during the pandemic, even with OMT enrollment, with an increase in preterm births and lower birth weights among infants born to mothers with substance use.

Maternal preterm birth prediction in the United States: a case-control database study

Background

Preterm birth is serious public health worldwide, and early prediction of preterm birth in pregnant women may provide assistance for timely intervention and reduction of preterm birth. This study aimed to develop a preterm birth prediction model that is readily available and convenient for clinical application.

Methods

Data used in this case-control study were extracted from the National Vital Statistics System (NVSS) database between 2018 and 2019. Univariate and multivariate logistic regression analyses were utilized to find factors associated with preterm birth. Odds ratio (OR) and 95% confidence interval (CI) were used as effect measures. The area under the curve (AUC), accuracy, sensitivity, and specificity were utilized as model performance evaluation metrics.

Results

Data from 3,006,989 pregnant women in 2019 and 3,039,922 pregnant women in 2018 were used for the model establishment and external validation, respectively. Of these 3,006,989 pregnant women, 324,700 (10.8%) had a preterm birth. Higher education level of pregnant women [bachelor (OR = 0.82; 95%CI, 0.81–0.84); master or above (OR = 0.82; 95%CI, 0.81–0.83)], pre-pregnancy overweight (OR = 0.96; 95%CI, 0.95–0.98) and obesity (OR = 0.94; 95%CI, 0.93–0.96), and prenatal care (OR = 0.48; 95%CI, 0.47–0.50) were associated with a reduced risk of preterm birth, while age ≥ 35 years (OR = 1.27; 95%CI, 1.26–1.29), black race (OR = 1.26; 95%CI, 1.23–1.29), pre-pregnancy underweight (OR = 1.26; 95%CI, 1.22–1.30), pregnancy smoking (OR = 1.27; 95%CI, 1.24–1.30), pre-pregnancy diabetes (OR = 2.08; 95%CI, 1.99–2.16), pre-pregnancy hypertension (OR = 2.22; 95%CI, 2.16–2.29), previous preterm birth (OR = 2.95; 95%CI, 2.88–3.01), and plurality (OR = 12.99; 95%CI, 12.73–13.24) were related to an increased risk of preterm birth. The AUC and accuracy of the prediction model in the testing set were 0.688 (95%CI, 0.686–0.689) and 0.762 (95%CI, 0.762–0.763), respectively. In addition, a nomogram based on information on pregnant women and their spouses was established to predict the risk of preterm birth in pregnant women.

Conclusions

The nomogram for predicting the risk of preterm birth in pregnant women had a good performance and the relevant predictors are readily available clinically, which may provide a simple tool for the prediction of preterm birth.

Prenatal exposure to ambient air pollution and adverse birth outcomes: An umbrella review of 36 systematic reviews and meta-analyses

Multiple systematic reviews and meta-analyses linked prenatal exposure to ambient air pollutants to adverse birth outcomes with mixed findings, including results indicating positive, negative, and null associations across the pregnancy periods. The objective of this study was to systematically summarise systematic reviews and meta-analyses on air pollutants and birth outcomes to assess the overall epidemiological evidence. Systematic reviews with/without meta-analyses on the association between air pollutants (NO₂, CO, O₃, SO₂, PM_2.5, and PM₁₀) and birth outcomes (preterm birth; stillbirth; spontaneous abortion; birth weight; low birth weight, LBW; small-for-gestational-age) up to March 30, 2022 were included. We searched PubMed, CINAHL, Scopus, Medline, Embase, and the Web of Science Core Collection, systematic reviews repositories, grey literature databases, internet search engines, and references of included studies. The consistency in the directions of the effect estimates was classified as more consistent positive or negative, less consistent positive or negative, unclear, and consistently null. Next, the confidence in the direction was rated as either convincing, probable, limited-suggestive, or limited non-conclusive evidence. Final synthesis included 36 systematic reviews (21 with and 15 without meta-analyses) that contained 295 distinct primary studies. PM_2.5 showed more consistent positive associations than other pollutants. The positive exposure-outcome associations based on the entire pregnancy period were more consistent than trimester-specific exposure averages. For whole pregnancy exposure, a more consistent positive association was found for PM_2.5 and birth weight reductions, particulate matter and spontaneous abortion, and SO₂ and LBW. Other exposure-outcome associations mostly showed less consistent positive associations and few unclear directions of associations. Almost all associations showed probable evidence. The available evidence indicates plausible causal effects of criteria air pollutants on birth outcomes. To strengthen the evidence, more high-quality studies are required, particularly from understudied settings, such as low-and-middle-income countries. However, the current evidence may warrant the adoption of the precautionary principle.

Urinary Phthalate Biomarkers during Pregnancy, and Maternal Endocrine Parameters in Association with Anthropometric Parameters of Newborns

Adverse birth outcomes present risk factors resulting in neonatal morbidity and mortality. Sufficient maternal hormonal concentrations are crucial for normal foetal development. Previous studies have shown a relationship between phthalate exposure and maternal hormonal levels during pregnancy. This study aims to investigate if neonatal anthropometric parameters are associated with maternal endocrine parameters during the ≤15th week of gestation and the third trimester of pregnancy concerning phthalate exposure in pregnant women from Nitra, Slovakia. We used high-performance liquid chromatography, tandem mass spectrometry (HPLC-MS/MS), and electro-chemiluminescence immunoassay to quantify urinary concentrations of phthalates and serum concentrations of hormones and sex hormone-binding globulin (SHBG), respectively. We observed a mostly positive correlation between neonatal anthropometric parameters (gestational age, birth length, birth weight, head circumference) and maternal concentration of phthalate metabolites (p ≤ 0.05). The hierarchical multivariate regression results showed a statistically significant association between Apgar score at 5 min after delivery, gestational age, birth weight, head circumference, and maternal endocrine parameters during pregnancy (p ≤ 0.05), adjusted to phthalate metabolites. To the best of our knowledge, our study is the first to indicate that prenatal exposure to phthalates may also affect birth outcomes through interaction with the maternal endocrine system.

Risk factors for hospitalisation in Welsh infants with a congenital anomaly

OBJECTIVES

To investigate risk factor associated with hospitalisation of infants with a congenital anomaly in Wales, UK.

DESIGN

A population-based cohort study.

SETTING

Data from the Welsh Congenital Anomaly Register and Information Service linked to the Patient Episode Database for Wales and livebirths and deaths from the Office for National Statistics.

PATIENTS

All livebirths between 1999 and 2015 with a diagnosis of a congenital anomaly, which was defined as a structural, metabolic, endocrine or genetic defect, as well as rare diseases of hereditary origin.

MAIN OUTCOME MEASURES

Adjusted OR (aOR) associated with 1 or 2+ hospital admissions in infancy versus no admissions were estimated for sociodemographic, maternal and infant factors using multinomial logistic regression for the subgroups of all, isolated, multiple and cardiovascular anomalies.

RESULTS

25 523 infants affected by congenital anomalies experienced a total of 50 705 admissions in infancy. Risk factors for ≥2 admissions were younger maternal age ≤24 years (aOR: 1.17; 95% CI 1.06 to 1.30), maternal smoking (aOR: 1.20; 1.10 to 1.31), preterm birth (aOR: 2.52; 2.25 to 2.83) and moderately severe congenital heart defects (aOR: 6.25; 4.47 to 8.74). Girls had an overall decreased risk of 2+ admissions (aOR: 0.84; 0.78 to 0.91). Preterm birth was a significant risk factor for admissions in all anomaly subgroups but the effect of the other characteristics varied according to anomaly subgroup.

CONCLUSIONS

Over two-thirds of infants with an anomaly are admitted to hospital during infancy. Our findings identified sociodemographic and clinical characteristics contributing to an increased risk of hospitalisation of infants with congenital anomalies.

Association of first trimester fetal heart rate and nuchal translucency with preterm birth

OBJECTIVE

To evaluate whether first trimester fetal heart rate (FHR) and nuchal translucency (NT) associate with preterm birth (PTB).

METHODS

This was a comparative case-control study of 518 normal pregnancies with no history of PTB, of which 272 delivered at term (TB) and 246 progressed to spontaneous PTB prior to 37, 34, 32, and 28 weeks. Fetal heart rate (FHR) and NT values at the first-trimester scan were compared by means of univariable (Mann-Whitney) and multivariable logistic regression analysis considering hourglass membranes (HM) as the most severe PTB subgroup. Finally, severity trends for both parameters were investigated using correlations with gestational age (GA) at delivery and Kruskal-Walls tests.

RESULTS

Regardless of GA at delivery, pregnancies affected with PTB showed higher FHR and thicker NT at the first trimester scan. The association was confirmed by the multivariable analysis and the severity trends, which paired the highest FHR and NT values with the most severe cases of PTB (p < .001) (p < .0001).

CONCLUSION

Fetuses with subsequent late, early and very early PTB show higher values of NT and FHR at the first-trimester scan.

Perinatal risk factors for pediatric onset type 1 diabetes, autoimmune thyroiditis, juvenile idiopathic arthritis, and inflammatory bowel diseases

Type 1 diabetes mellitus (DM), autoimmune thyroiditis (AIT), juvenile idiopathic arthritis (JIA), and inflammatory bowel diseases (IBD) are common pediatric autoimmune diseases with unknown risk factors. Using nationwide registers, we searched for their perinatal risk factors. Our study followed up 11,407 children (born 2000-2005) for a median of 16.6 years (from birth to 2018). Of them, 2.15% received primary diagnosis and 0.08% also secondary: 0.89% had DM, 0.60% had AIT, 0.48% had JIA, and 0.25% had IBD. The incidences per 100,000 children/year were 106.1 for DM, 46.0 for AIT, 55.0 for JIA, and 23.7 for IBD. There were more preterm births (< 37 weeks) among children with studied autoimmune diseases compared with the rest of the cohort (8.6% vs. 5.3%, p = 0.035). Among those born preterm, children with studied autoimmune diseases received more postnatal antibiotics compared with other preterm children in the cohort (47.6% vs. 27.7%, p = 0.046). Children with IBD were born to older mothers compared with those without studied diagnoses (33.0 vs 30.2, p = 0.004).Conclusion: Preterm birth was a shared risk factor for autoimmune diseases in our study, especially when combined with postnatal antibiotic treatments. High maternal age was associated with IBD. What is Known: • Type 1 diabetes (DM), autoimmune thyroiditis (AIT), juvenile idiopathic arthritis (JIA), and inflammatory bowel diseases (IBD) are common pediatric autoimmune diseases • It is unclear whether these diseases have shared risk factors, since there are no previous simultaneous epidemiological nor follow-up studies on them in one cohort  What is New: • Preterm births were more common in children with DM, AIT, JIA, or IBD compared with other children in the cohort, and preterm children who developed these diseases recieved more postnatal antibiotics compared with other preterm children • High maternal age was associated with IBD.