The role of confounding in the association between pregnancy complications and subsequent preterm birth: a cohort study

Mediating role of gestational weight gain in the relationship between socioeconomic status and preterm birth: a Chinese population-based study

BACKGROUND

The modifiable mechanisms underlying the association between socioeconomic status (SES) and preterm birth remain unclear. This study aimed to investigate the relationship between preterm birth and maternal SES or gestational weight gain (GWG), as well as the role of GWG in mediating SES disparities in preterm birth.

METHODS

Data was from a hospital-based sub-study of physical growth and development survey for Chinese newborns with various gestational ages. Singleton newborns aged from 24 to 42weeks' gestation and their mothers were included. Using information from maternal questionnaire, a composite SES was constructed with parental education and family annual income. GWG as mediator was calculated by deducting pre-pregnancy weight from maternal weight at delivery. Logistic regression model was adopted to investigate the association of preterm birth with SES or GWG. Causal mediation analysis was performed to measure mediating effect of GWG on the pathway from SES to preterm birth.

RESULTS

After controlling for potential confounders, risk of preterm birth was reduced by 12.4% (OR = 0.876, 95%CI:0.855-0.879) for per one-kilogram increase of GWG, and risk of preterm birth was reduced by 24% (OR = 0.760, 95%CI: 0.717-0.806) for per one-unit increase of SES score. Mediation analysis supported a significant association between higher SES and decreased risk of preterm partly through higher GWG, in which estimated proportion mediated by GWG was 13.04% (95%CI: 11.89-16.25). GWG also played a significant role as a mediator when socioeconomic status was indicated by maternal education, paternal education or family income. GWG mediated approximately 11.03% (95% CI: 8.56-18.25) of the total effect of SES on very preterm birth, which was greater than that for moderate preterm birth (6.72%, 95%CI: 2.72-31.52) and late preterm birth (9.04%, 95%CI: 5.24-24.04). A series of sensitive analysis confirmed the robustness of association of interest.

CONCLUSION

Increased GWG and higher socioeconomic status are strongly associated with a lower risk of preterm birth. GWG mediates socioeconomic disparities in preterm birth, most notably in very preterm birth. Understanding this mechanism will aid in the development of interventions and policy for maternal and child health care.

The effects of pre-eclampsia on social and emotional developmental vulnerability in children at age five in Western Australia: A population data linkage study

BACKGROUND

It is important to explore factors that may hinder early childhood development in AEDC Emotional Maturity and Social Competence domains as these underpin the foundation for health, well-being, and productivity over the life course. No previous study has examined whether, or to what extent, preeclampsia increases the risk of developmental vulnerability in social and emotional domains in early childhood.

METHODS

We conducted a retrospective population-based cohort study on the association between preeclampsia and childhood developmental vulnerability in emotional maturity and social competence domains in children born in Western Australia in 2009, 2012 and 2015. We obtained records of births, developmental anomalies, midwives notifications and hospitalisations. These data were linked to the Australian Early Development Census (AEDC), from which developmental vulnerability in emotional maturity and social competence domains at a median age of 5 years was ascertained. Causal relative risks (RR) were estimated with doubly robust estimation.

RESULTS

A total of 64,391 mother-offspring pairs were included in the final analysis. For the whole cohort, approximately 25 % and 23 % of children were classified as developmentally vulnerable or at-risk on AEDC emotional maturity and social competence domains, respectively. Approximately 2.8 % of children were exposed in utero to preeclampsia. Children exposed to preeclampsia were more likely to be classified as developmentally vulnerable or at-risk on the emotional maturity (RR = 1.19, 95%CI:1.11-1.28) and social competence domains (RR = 1.22, 95 % CI:1.13-1.31).

CONCLUSION

Children exposed to pre-eclampsia in utero were more likely to be developmentally vulnerable in emotional maturity and social competence domains in this cohort. Our findings provide new insights into the harmful effect of preeclampsia on childhood developmental vulnerability.

Maternal hypertensive traits and adverse outcome in pregnancy: a Mendelian randomization study

INTRODUCTION

Hypertensive disorders of pregnancy are associated with adverse feto-maternal outcomes. Existing evidence is mostly limited to observational studies, which are liable to confounding and bias. This study investigated the causal relevance of component hypertensive indices on multiple adverse pregnancy outcomes using Mendelian randomization.

METHODS

Uncorrelated ( r2  < 0.001) genome-wide significant ( P  < 5 × 10 -8 ) single-nucleotide polymorphisms associated with SBP, DBP and pulse pressure (PP) were selected as instrumental variables. Genetic association estimates for outcomes of preeclampsia or eclampsia, preterm birth, placental abruption and hemorrhage in early pregnancy were extracted from summary statistics of genome-wide association studies in the FinnGen cohort. Two-sample, inverse-variance weighted Mendelian randomization formed the primary analysis method. Odds ratios (OR) are presented per-10 mmHg higher genetically predicted hypertensive index.

RESULTS

Higher genetically predicted SBP were associated with higher odds of preeclampsia or eclampsia [OR 1.81, 95% confidence interval (CI) 1.68-1.96, P  = 5.45 × 10 -49 ], preterm birth (OR 1.09, 95% CI 1.03-1.16, P  = 0.005) and placental abruption (OR 1.33, 95% CI 1.05-1.68, P  = 0.016). Higher genetically-predicted DBP was associated with preeclampsia or eclampsia (OR 2.54, 95% CI 2.21-2.92, P  = 5.35 × 10 -40 ). Higher genetically predicted PP was associated with preeclampsia or eclampsia (OR 1.68, 95% CI 1.47-1.92, P  = 1.9 × 10 -14 ) and preterm birth (OR 1.18, 95% CI 1.06-1.30, P  = 0.002).

CONCLUSION

This study provides genetic evidence to support causal associations of SBP, DBP and PP on multiple adverse outcomes of pregnancy. SBP and PP were associated with the broadest range of adverse outcomes, suggesting that optimized management of blood pressure, particularly SBP, is a key priority to improve feto-maternal health.

The effect of prenatal cannabis exposure on offspring preterm birth: a cumulative meta-analysis

BACKGROUND AND AIMS

Mixed results have been reported on the association between prenatal cannabis exposure and preterm birth. This study aimed to examine the magnitude and consistency of associations reported between prenatal cannabis exposure and preterm birth.

METHODS

This review was guided by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. We performed a comprehensive search of the literature on the following electronic databases: PubMed, EMBASE, SCOPUS, Psych-INFO and Web of Science. The revised version of the Newcastle-Ottawa Scale (NOS) was used to appraise the methodological quality of the studies included in this review. Inverse variance weighted random-effects cumulative meta-analysis was undertaken to pool adjusted odds ratios (aOR) after sequential inclusion of each newly published study over time. The OR and 95% confidence interval (CI) limits required (stability threshold) for a new study to move the cumulative odds ratio to the null were also computed.

RESULTS

A total of 27 observational studies published between 1986 and 2022 were included in the final cumulative meta-analysis. The sample size of the studies ranged from 304 to 4.83 million births. Prenatal cannabis exposure was associated with an increased risk of preterm birth (pooled aOR = 1.35, 95% CI = 1.24-1.48). The stability threshold was 0.74 (95% CI limit = 0.81) by the end of 2022.

CONCLUSIONS

Offspring exposed to maternal prenatal cannabis use was associated with higher risk of preterm birth, which warrants public health messages to avoid such exposure, particularly during pregnancy.

Calcium, Potassium, Sodium, and Magnesium Concentrations in the Placenta, Umbilical Cord, and Fetal Membrane from Women with Multiple Pregnancies

Calcium (Ca), potassium (K), sodium (Na), and magnesium (Mg) are the elements responsible for the fundamental metabolic and biochemical processes in the cells of the body. The demand for these elements increases significantly during pregnancy, where an adequate supply protects women from the hypertension common in pre-eclampsia and preterm labor. This study aimed to evaluate the association between macro-elements (Ca, Mg, Na, and K) in the placenta, fetal membrane, and umbilical cord and the morphometric parameters of newborns from multiple pregnancies. The study involved 57 pregnant European women with healthy uncomplicated twin pregnancies (n = 52) and triple pregnancies (n = 5); 40 pairs of dichorionic diamniotic twins, 11 pairs of monochorionic diamniotic twins, 1 pair of monochorionic monoamniotic twins, 3 trichorionic triamniotic triplets, and 2 dichorionic triamniotic triplets. Placentas (n = 107), umbilical cords (n = 114), and fetal membranes (n = 112) were collected immediately following delivery, and then weighed and measured. The levels of Ca, K, Na, and Mg were determined using inductively coupled plasma atomic emission spectroscopy (ICP-OES) in a Thermo Scientific ICAP 7400 Duo (Waltham, MA, USA). The respective mean concentrations of Ca, K, Na, and Mg (mg/kg^-1 dry mass) were: 2466, 8873, 9323, and 436 in the placenta; 957, 6173, 26,757, and 326 in the umbilical cord, and 1252, 7460, 13,562, and 370 in the fetal membrane. In the studied materials from northwestern Poland, we found strong positive correlations between Ca and Mg concentrations in both the umbilical cord (r = 0.81, p = 0.00) and the fetal membrane (r = 0.73, p = 0.00); between K and Mg concentrations in the umbilical cord (r = 0.73, p = 0.00); between Ca and K concentrations in the fetal membrane (r = 0.73, p = 0.00), and we found moderately positive correlations between placental Ca concentration and placental weight (ρ = 0.42, p = 0.00) and between umbilical cord Mg concentrations and the length of the pregnancy (ρ = 0.42, p = 0.00). Negative correlations were found between Na and Ca concentrations in the fetal membrane (r = -0.40, p = 0.00) and Na concentrations in the fetal membrane and Mg concentrations in the placenta (r = -0.16, p = 0.02). Negative correlations were confirmed between the length of pregnancy and head circumference (ρ = -0.42; p = 0.00), infant weight (ρ = -0.42; p = 0.00), infant length (ρ = -0.49; p = 0.00), shoulder width (ρ = -0.49; p = 0.00); and between the infant weight and head circumference (ρ = -0.62; p = 0.00), weight before delivery (ρ = -0.36; p = 0.00), infant length (ρ = -0.45; p = 0.00), shoulder width (ρ = -0.63; p = 0.00), and weight gain during pregnancy (ρ = -0.31; p = 0.01). We found statistically significant correlations between cigarette smoking before pregnancy and the women's weight before delivery (ρ = 0.32, p = 0.00), and a negative correlation between the women's ages and infant head circumference (ρ = -0.20, p = 0.02). This is probably the first study to evaluate Ca, Na, K, and Mg concentrations in the afterbirth tissues of multiple pregnancies. It adds to the knowledge of elemental concentrations in multiple pregnancies and their possible effects on fetal morphometric parameters.