Shujin Zhou

Similarities and differences between the risk factors for gestational hypertension and preeclampsia: A population based cohort study in south China

OBJECTIVES To compare the risk factors for gestational hypertension (GH) and preeclampsia (PE) in the same population, which may provide clues to better understanding of their etiologic mechanisms. METHODS We conducted a cohort study in Liuyang, China, during 2010-2011. Twelve potential risk factors were investigated, including maternal age, body mass index at first antenatal visit, gender of newborn, parity, abortion history, smoking history, family history of hypertension, gestational diabetes mellitus, pregnancy complications of diabetes mellitus/renal disease/cardiac disease, reproductive tract infection, season of delivery, and district level average per capita income. Logistic regression were used to estimate odds ratios for potential risk factors. RESULTS Of 6223 pregnancies, 1.8% was complicated by PE, and 5.4% by GH. Maternal age older than 35, body mass index above 24, and pregnancy complicated with gestational diabetes mellitus increased the risk of both PE and GH, while with different effect sizes. Primiparity and deliver in winter and spring (compared with summer delivery) were risk factors for GH only. Pregnancy complicated with diabetes mellitus/renal disease/cardiac disease was risk factor for PE only. Significantly lower risk of GH was observed for women younger than 25 or with low body mass index in the first trimester. Mothers carrying a male fetus were more likely to develop PE. CONCLUSIONS Risk factors for GH and PE were not exactly the same. Underling those differences might be their different etiology and mechanism. To confirm the similarities and differences been found in single study, it is important to conduct investigation in other population.

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.

Maternal Chronic HBV Infection Would Not Increase the Risk of Pregnancy-Induced Hypertension – Results from Pregnancy Cohort in Liuyang Rural China

The relationship between maternal HBV (hepatitis B virus) infection and pregnancy-induced hypertension (PIH) is inconclusive. Few studies have been conducted in rural areas of China. In order to examine the association between maternal chronic HBV infection and risk of PIH in Liuyang rural area China, we enrolled 6,195 eligible pregnant women in 2010–2011 in selected 14 towns of Liuyang on their first prenatal visit to local maternity care unit. A total of 461 subjects (7.44% (95%CI: 6.79%, 8.10%)) were identified with positive HBsAg status (exposed group) and 5734 were non-HBV carriers (unexposed group). Multivariate log-binomial regression models were used to estimate the risk of PIH, gestational hypertension (GH), and preeclampsia (PE) in relation to maternal chronic HBV infection. There are total of 455 subjects diagnosed with PIH (7.34% (95%CI: 6.70%, 7.99%)), including 371 GH (5.99% (95%CI: 5.40%, 6.58%)) and 81 PE (1.31% (95%CI: 1.07%, 1.64%)). The crude risk ratio between PIH, GH, PE and maternal HBV infection were 1.20 (95%CI: 0.88, 1.64), 1.30(95%CI: 0.93, 1.81) and 0.79 (95%CI: 0.32, 1.93), respectively. After adjustment for gravidity history, abortion history, family history of Diabetes Mellitus (DM) and family history of hypertension, positive HBsAg status was still not significantly associated with PIH (RR = 1.18, 95%CI: 0.87, 1.62), GH (RR = 1.27, 95%CI: 0.91, 1.78) or PE (RR = 0.79, 95%CI: 0.32, 1.95). Additional adjustment for maternal age, marital status, parity history, family history of DM, Body Mass Index at first antenatal visit, folic acid supplementation, smoking status during pregnancy and economic status of living area, multivariate analysis provided similar results. In conclusion, our study found that maternal chronic HBV infection prevalence rate is 7.4% among Liuyang rural area and there is no significant association between maternal HBV infection and the risk of PIH, GH or PE.

Renin–angiotensin–aldosterone system gene polymorphisms in gestational hypertension and preeclampsia: A case–control gene-association study

Pregnancy-induced hypertension (PIH, including preeclampsia [PE] and gestational hypertension [GH]) and cardiovascular diseases (CVDs) have some metabolic changes and risk factors in common. Many studies have reported associations between single nucleotide polymorphisms (SNPs) of renin–angiotensin–aldosterone system (RAAS) genes and CVDs (particularly hypertension), and their findings have provided candidate SNPs for research on genetic correlates of PIH. We explored the association between hypertension-related RAAS SNPs and PIH in a Chinese population. A total of 130 cases with PE, 67 cases with GH, and 316 controls were recruited. Six candidate SNPs of the RAAS system were selected. Multiple logistic regression analysis adjusting for maternal age, fetal sex, and gestational diabetes mellitus showed significant associations between angiotensinogen (AGT) rs3789678 T/C and GH (p = 0.0088) and between angiotensin II receptor type 1 (AGTR1) rs275645 G/A and PE (p = 0.0082). The study population was further stratified by maternal age (<30 and ≥30 years), and stratified and crossover analyses were conducted to determine genetic associations in different age groups. Our findings suggest that the impacts of different SNPs might be affected by maternal age; however, the effect of this potential gene–age interaction on PIH needs further exploration.

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.

Maternal exposure to the production of fireworks and reduced rate of new onset hypertension in pregnancy

Background: Carbon monoxide (CO) is one of the main substances contained in fireworks. Previous studies suggested that CO may have protective effect on the development of hypertension of pregnancy. Method: The authors conducted a prospective cohort study in Liuyang, Hunan, China between January 2010 and December 2011. Demographic and life-style variables of the participating pregnant women were obtained through structured interview with the women and clinical data were retrieved from antenatal medical records. Density of fireworks factories was defined as the number of fireworks factories per 1000 residents in the township where the mothers resided during pregnancy. Multiple logistic regression analysis was used to analyze the independent association between maternal exposure to the production of fireworks and new onset hypertension in pregnancy. Results: A total of 5976 pregnant women were included in the final analysis. Density of fireworks factories was inversely correlated with incidence of new onset hypertension in pregnancy (Pearson correlation coefficient = −0.29, p < 0.001). Multiple logistic regression analysis showed that, compared with women who resided during pregnancy in a township with 0–0.25 fireworks factories per 1000 residents, the rates of new onset hypertension in pregnancy in women who resided in a township with 0.26–1.00 fireworks factories per 1000 residents (Odds Ratio = 0.66, 95% confidence interval: 0.46, 0.96) and >1.5 fireworks factories per 1000 residents (Odds Ratio = 0.65, 95% confidence interval: 0.44, 0.97) were reduced by more than 30%. Conclusion: Maternal exposure to the high density of fireworks factories is associated with reduced risk of developing new onset hypertension in pregnancy.

Exposure to firework chemicals from production factories in pregnant women and risk of preterm birth occurrence in Liuyang, China

ABSTRACT In the production of fireworks, various pollutants including particles of metals and organic compounds are released into the environment. Although the adverse effects of these air pollutants are known, the impact on pregnant women residing in this area remains to be determined. The aim of this study was to examine the association between maternal exposure to fireworks production chemicals and frequency of preterm birth in Liuyang, China. Maternal exposure to fireworks production was estimated at the residential district level and assessed using factory density, which was defined as the number of fireworks factories per 1000 residents in each district. The association of maternal exposure to particulates released from fireworks production plants with frequency of preterm birth was determined using data obtained from a cohort study conducted in Liuyang, China. Data were analyzed utilizing linear regression and logistic regression. There was no significant association between factory density and spontaneous preterm or medically induced preterm birth. Unexpectedly, pregnant women residing in areas with higher density of fireworks factories were at a reduced risk of preterm premature rupture of membranes (PPROM). Data demonstrated that residential density of fireworks factories appeared to be negatively correlated with preterm birth rate as evidenced by PPROM. At present, it is difficult to reconcile the inverse relationship between firework chemical exposure and frequency of preterm births as ambient particulate inhalation is known to adversely affect preterm birth occurrence.