Minxue Shen

Comparison of risk factors and outcomes of gestational hypertension and pre-eclampsia

Background It remains an enigma whether gestational hypertension (GH) and pre-eclampsia (PE) are distinct entities or different spectrum of the same disease. We aimed to compare the risk factors and outcomes between GH and PE. Method A total of 7,633 pregnant women recruited between 12 and 20 weeks of gestation in the Ottawa and Kingston Birth Cohort from 2002 to 2009 were included in the analysis. Cox proportional hazards model was used to identify and compare the risk factors for GH and PE by treating gestational age at delivery as the survival time. Logistic regression model was used to compare outcome. Subgroup analysis was performed for early- and late-onset PE. Results GH and PE shared most risk factors including overweight and obesity, nulliparity, PE history, type 1 and 2 diabetes, and twin birth. Effect size of PE history (RR = 14.1 for GH vs. RR = 6.4 for PE) and twin birth (RR = 4.8 for GH vs. RR = 10.3 for PE) showed substantial difference. Risk factors modified gestational age at delivery in patients with GH and PE in similar pattern. Subgroup analysis showed that early- and late-onset PE shared some risk factors with different effect sizes, whereas folic acid supplementation showed protective effect for early-onset PE only. PE was strongly associated with several adverse outcomes including cesarean section, placental abruption, small for gestational age, preterm birth, and 5 min Apgar score < 7, whereas GH was associated with increased risk of preterm birth only. Conclusions GH and PE shared common risk factors. Differences in effect sizes of risk factors and outcomes indicate that the conditions may have different pathophysiology and mechanism.

Maternal Blood Pressure Before Pregnancy and Sex of the Baby: A Prospective Preconception Cohort Study

BACKGROUND Population‐level sociologic studies have suggested that adverse societal conditions may affect fetal viability in a sex‐specific manner and thereby modify the ratio of male vs. female babies. This concept suggests that there may exist certain physiologic features in a woman that relate to her likelihood of delivering a boy or girl. We thus established a preconception cohort to prospectively evaluate the relationship between maternal pregravid health and sex of the baby. METHODS In this analysis nested within an observational cohort study, 1,411 newly married women in Liuyang, China, underwent pregravid cardiometabolic characterization (including anthropometry and measurement of blood pressure, cholesterol, triglycerides, and glucose) at median 26.3 weeks before a singleton pregnancy, delivering at 39.0 ± 1.3 weeks gestation. RESULTS Systolic blood pressure before pregnancy was higher in women who delivered a boy than in those who had a girl (112.5 ± 11.9 vs. 109.6 ± 12.0 mm Hg, P < 0.0001). The prevalence of a male baby progressively increased across quintiles of pregravid systolic blood pressure (P < 0.0001). After covariate adjustment, mean adjusted pregravid systolic blood pressure was higher in mothers of boys vs. girls (106.0 vs. 103.3 mm Hg, P = 0.0015). On logistic regression analysis, pregravid systolic blood pressure emerged as the only significant predictor of having a male baby (adjusted odds ratio = 1.017 per mm Hg, 95% confidence interval = 1.007‐1.028). The pregravid difference in blood pressure between mothers of boys and girls was not present during any trimester of pregnancy. CONCLUSION Maternal blood pressure before pregnancy is a previously unrecognized factor that may be associated with the likelihood of delivering a boy or girl.

Effect of folic acid supplementation during pregnancy on gestational hypertension/preeclampsia: A systematic review and meta-analysis

ABSTRACT Objective: To evaluate the effect of folic acid supplementation during pregnancy on the risk of gestational hypertension/preeclampsia. Methods: A systematic review and meta-analysis were conducted. Medline, Embase, Scopus, and the Web of Science were searched from inception to December 2014. Results: Out of 1224 potentially relevant studies, 13 studies met our inclusion criteria (2 randomized controlled trials (RCTs), 10 cohort studies, and 1 case–control study). The pooled relative risk (RR) and 95% confidence interval (CI) of the two RCTs were 0.62 (0.45–0.87) in the trial arm as compared with the placebo arm. The pooled RR was 0.92 (95% CI: 0.79–1.08) for nine cohort studies with available data on folic acid supplementation in pregnancy and gestational hypertension/preeclampsia. Pooled RR was 0.88 (95% CI: 0.76–1.02) for eight cohort studies with available data on folic acid supplementation and preeclampsia. Conclusion: Whether folic acid supplementation in pregnancy can prevent the occurrence of gestational hypertension/preeclampsia remains uncertain.

Serum and red-blood-cell folate demonstrate differential associations with BMI in pregnant women.

OBJECTIVE To examine the association between BMI and folate concentrations in serum and red blood cells (RBC) in pregnant women. DESIGN A cross-sectional comparison of folate concentrations in serum and RBC sampled simultaneously from the same individual. SETTING The Ottawa Hospital and Kingston General Hospital, Ontario, Canada. SUBJECTS Pregnant women recruited between 12 and 20 weeks of gestation. RESULTS A total of 869 pregnant women recruited from April 2008 to April 2009 were included in the final analysis. Serum folate was inversely associated and RBC folate positively associated with BMI, after adjusting for folic acid supplementation, age, gestational age at blood sample collection, race, maternal education, annual income, smoking and MTHFR 677C→T genotype. In stratified analyses, this differential association was significant in women with the MTHFR CC variant. In women with the CT and TT variants, the differential associations were in the same direction but not significant. Folic acid supplementation during pregnancy did not alter the differential association of BMI with serum and RBC folate concentration. This indicates that the current RBC folate cut-off approach for assessing risk of neural tube defects in obese women may be limited. CONCLUSIONS BMI is inversely associated with serum folate and positively associated with RBC folate in pregnant women, especially for those with the MTHFR CC variant.

Trajectory of blood pressure change during pregnancy and the role of pre-gravid blood pressure: a functional data analysis approach

The study aims to examine the blood pressure (BP) trajectory during pregnancy and its association with pre-gravid BP level. In a pre-conception cohort study, newly-married women in Liuyang, China underwent pre-gravid measurements and were followed throughout the pregnancy. BP was measured at pre-conception and again throughout pregnancy. The functional principal component analysis was used to examine the trajectory of BP changes during pregnancy. A total of 1282 women with a singleton pregnancy who had both pre-conception and gestational BP measurements performed were included in the final analysis. The results showed that BP decreased significantly in early pregnancy and increased thereafter, without BP drop around 20 weeks of gestation. Pre-gravid BP level was inversely associated with the BP drop in early pregnancy, such that women with higher pre-gravid BP had greater BP drop at the beginning, while women with the lowest pre-gravid BP level demonstrated no obvious BP drop throughout the entire pregnancy.

Association of Timing of Weight Gain in Pregnancy With Infant Birth Weight

Importance Gestational weight gain is a determinant of infant birth weight, but it is unclear whether its timing in pregnancy may hold implications in this regard. Previous studies have yielded conflicting findings on the association of maternal weight gain in early pregnancy with birth weight. However, as these studies have typically recruited women during the first trimester, they are inherently limited by a reliance on self-reported pregravid weight. Objective To evaluate the associations of directly measured maternal pregravid weight and the timing of subsequent weight gain across pregnancy with infant birth weight. Design, Setting, and Participants In this prospective, preconception, observational cohort study, 1164 newly married women in Liuyang, China, underwent pregravid evaluation at a median of 19.9 weeks before a singleton pregnancy during which they underwent serial weight measurements. The study was conducted from February 1, 2009, to November 4, 2015. Data analysis was performed between September 1, 2016, and May 6, 2017. Exposure Maternal weight gain was calculated for the following 10 gestational intervals: from pregravid to less than 14, 14 to 18, 19 to 23, 24 to 28, 29 to 30, 31 to 32, 33 to 34, 35 to 36, 37 to 38, and 39 to 40 weeks. Main Outcomes and Measures Associations of pregravid weight and weight gain within each of the 10 gestational intervals with the outcome of infant birth weight. Results The mean (SD) age of the 1164 women included in the study was 25.3 (3.1) years. Pregravid weight was consistently associated with infant birth weight. However, among the 10 gestational intervals, only weight gain from pregravid to 14 weeks and from 14 to 18 weeks was associated with birth weight. Birth weight increased by 13.6 g/kg (95% CI, 3.2-24.1 g/kg) of maternal weight gain from pregravid to 14 weeks and by 26.1 g/kg (95% CI, 3.8-48.4 g/kg) of maternal weight gain from 14 to 18 weeks. Conclusion and Relevance Maternal weight only in the first half of gestation is a determinant of infant birth weight. Before pregnancy and early gestation may be a critical window for intervention to affect subsequent birth weight.

Serum Folate Shows an Inverse Association with Blood Pressure in a Cohort of Chinese Women of Childbearing Age: A Cross-Sectional Study

Background It has been reported that higher folate intake from food and supplementation is associated with decreased blood pressure (BP). The association between serum folate concentration and BP has been examined in few studies. We aim to examine the association between serum folate and BP levels in a cohort of young Chinese women. Methods We used the baseline data from a pre-conception cohort of women of childbearing age in Liuyang, China, for this study. Demographic data were collected by structured interview. Serum folate concentration was measured by immunoassay, and homocysteine, blood glucose, triglyceride and total cholesterol were measured through standardized clinical procedures. Multiple linear regression and principal component regression model were applied in the analysis. Results A total of 1,532 healthy normotensive non-pregnant women were included in the final analysis. The mean concentration of serum folate was 7.5 ± 5.4 nmol/L and 55% of the women presented with folate deficiency (< 6.8 nmol/L). Multiple linear regression and principal component regression showed that serum folate levels were inversely associated with systolic and diastolic BP, after adjusting for demographic, anthropometric, and biochemical factors. Conclusions Serum folate is inversely associated with BP in non-pregnant women of childbearing age with high prevalence of folate deficiency.