Hongtian Li

Folic Acid Supplementation During Early Pregnancy and the Risk of Gestational Hypertension and Preeclampsia

Emerging evidence has suggested that folic acid–containing multivitamins may markedly reduce the risk of gestational hypertension or preeclampsia. We examined whether maternal supplementation with folic acid alone during early pregnancy can prevent the occurrence of gestational hypertension and preeclampsia. The data are from a large population-based cohort study established to evaluate the effectiveness of the campaign to prevent neural tube defects with folic acid supplementation in China. We selected participants who were registered in 2 southern provinces, had exact information on folic acid use, and were not affected by chronic hypertension or diabetes mellitus before 20 weeks gestation. A logistic regression model was used to adjust for the effects of the main potential confounders, including age, body mass index, education, occupation, parity, and multiple births. The study size had 99.9% power (&agr;=0.05) to detect a decrease of 10% over the unexposed rate of 9.4% for gestational hypertension. Among the 193 554 women (47.9% took folic acid, 52.1% did not), the overall incidence of gestational hypertension and preeclampsia was 9.5% and 2.5%, respectively. The incidence of gestational hypertension and preeclampsia was 9.7% and 2.5% for women who took folic acid, and 9.4% and 2.4% for women who did not use it. The adjusted risk ratio associated with folic acid use was 1.08 (95% confidence interval, 1.04–1.11) for gestational hypertension and 1.11 (95% confidence interval, 1.04–1.18) for preeclampsia. Our findings suggest that daily consumption of 400 &mgr;g folic acid alone during early pregnancy cannot prevent the occurrence of gestational hypertension and preeclampsia.

Caesarean delivery, caesarean delivery on maternal request and childhood overweight: a Chinese birth cohort study of 181 380 children.

What is already known about this subject Both rates of caesarean section and childhood overweight have been steadily increasing over the past decade in many parts of the world. Caesarean delivery on maternal request contributes remarkably to the rising trend of caesarean births. A few small‐scale studies suggest that caesarean section may be associated with later overweight and obesity, whereas little is known about the impact of caesarean delivery on maternal request.

Caesarean delivery on maternal request and childhood psychopathology: a retrospective cohort study in China

Please cite this paper as: Li H‐T, Ye R, Achenbach T, Ren A, Pei L, Zheng X, Liu J‐M. Caesarean delivery on maternal request and childhood psychopathology: a retrospective cohort study in China. BJOG 2011;118:42–48.

Periconceptional folic acid supplementation and the risk of preterm births in China: a large prospective cohort study

BACKGROUND Folic acid-containing multivitamins have been associated with a reduced risk of preterm birth. We examined whether periconceptional use of folic acid alone reduced this risk. METHODS Data were derived from a large population-based cohort study conducted in China to evaluate the prevention of neural tube defects with folic acid supplementation. The sample comprised 207 936 singleton live births delivered at gestational ages of 20-42 weeks to women from two provinces in southern China. Healthcare workers recorded folic acid intake prospectively each month. Gestational age calculation was based on the first day of the last menstrual period. Preterm births were categorized into three clinical subtypes: iatrogenic preterm birth, preterm premature rupture of membranes (PPROM) and spontaneous preterm birth. Logistic regression was used to evaluate the association between folic acid use and the risk of preterm birth, adjusting for potential confounders. RESULTS The incidence of preterm birth was significantly lower among folic acid users (5.28%) than among non-users (6.10%). Folic acid use showed a 14% risk reduction for preterm birth overall [adjusted risk ratio (RR) = 0.86, 95% confidence interval (CI) 0.82-0.90]. This association was strongest for spontaneous preterm birth (adjusted RR = 0.81, 95% CI 0.78-0.86) and was not significant for iatrogenic preterm birth (adjusted RR = 0.97, 95% CI 0.88-1.07) or PPROM (adjusted RR = 1.07, 95% CI 0.93-1.23). CONCLUSIONS Daily intake of 400 μg folic acid alone during the periconceptional period was associated with a reduced risk of spontaneous preterm birth.

Association of cesarean delivery with anemia in infants and children in 2 large longitudinal Chinese birth cohorts

BACKGROUND Cesarean delivery may reduce placental-fetal transfusion and thus increase the risk of early childhood anemia compared with vaginal delivery, but this notion has not been carefully studied in longitudinal cohorts. OBJECTIVE The aim was to assess the association of cesarean delivery with anemia in infants and children in 2 longitudinal Chinese birth cohorts from different socioeconomic settings. DESIGN Cohort 1 was recruited from 5 counties in northeastern China and cohort 2 from 21 counties or cities in southeastern China. Cohort 1 involved 17,423 infants born during 2006-2009 to mothers with early pregnancy baseline hemoglobin concentrations ranging from 100 to 177 g/L, whereas cohort 2 involved 122,777 children born during 1993-1996 to mothers with baseline hemoglobin concentrations ranging from 60 to 190 g/L. The main outcomes were anemia at 6 and 12 mo in cohort 1 and at 58 mo in cohort 2. Multiple logistic regressions were used to estimate adjusted ORs of anemia for cesarean compared with vaginal delivery. Stratified analyses were performed by pre- and postlabor cesarean delivery and according to maternal baseline hemoglobin concentration (≤109, 110-119, 120-129, and ≥130 g/L). RESULTS Cesarean delivery was not associated with anemia at 6 mo in cohort 1 (adjusted OR: 1.05; 95% CI: 0.93, 1.19); however, cesarean delivery was associated with increased anemia at 12 mo in cohort 1 (adjusted OR: 1.19; 95% CI: 1.04, 1.37) and at 58 mo in cohort 2 (adjusted OR: 1.11; 95% CI: 1.08, 1.15). The positive associations for anemia at 12 and 58 mo were consistent across maternal hemoglobin subgroups and persisted for cesarean delivery subtypes. CONCLUSION Cesarean delivery is likely associated with anemia in children, which suggests a possible need for exploring changes in obstetric care that might prevent anemia in cesarean-delivered children.

C-reactive protein increases with gestational age during pregnancy among Chinese women.

To examine the concentration of C‐reactive protein (CRP) in relation to gestational weeks during pregnancy among Chinese women.

Maternal Obesity, Caesarean Delivery and Caesarean Delivery on Maternal Request: a Cohort Analysis from China

BACKGROUND To quantify the association between maternal obesity and caesarean delivery, particularly caesarean delivery on maternal request (CDMR), a fast-growing component of caesarean delivery in many nations. METHODS We followed 1,019,576 nulliparous women registered in the Perinatal Healthcare Surveillance System during 1993-2010. Maternal body mass index (BMI, kg/m(2) ), before pregnancy or during early pregnancy, was classified as underweight (<18.5), normal (18.5 to <23; reference), overweight (23 to <27.5), or obese (≥27.5), consistent with World Health Organization guidelines for Asian people. The association between maternal obesity and overall caesarean and its subtypes was modelled using log-binomial regression. RESULTS During the 18-year period, 404,971 (39.7%) caesareans and 93,927 (9.2%) CDMRs were identified. Maternal obesity was positively associated with overall caesarean and CDMR. Adjusted risk ratios for overall caesarean in the four ascending BMI categories were 0.96 [95% confidence interval (CI) 0.94, 0.97], 1.00 (Reference), 1.16 [95% CI 1.14, 1.18], 1.39 [95% CI 1.43, 1.54], and for CDMR were 0.95 [95% CI 0.94, 0.96], 1.00 (Reference), 1.20 [95% CI 1.18, 1.22], 1.48 [95% CI 1.433, 1.54]. Positive associations were consistently found in women residing in southern and northern provinces and in subgroups stratified by year of delivery, urban or rural residence, maternal age, education, level of delivering hospital, and birthweight. CONCLUSIONS In a large Chinese cohort study, maternal obesity was associated with an increased risk of caesarean delivery and its subtypes, including CDMR. Given the rising global prevalence of obesity, and in view of the growth of CDMR, it seems likely that caesarean births will increase, unless there are changes in obstetrical practice.

A Correlation Study of DHA Dietary Intake and Plasma, Erythrocyte and Breast Milk DHA Concentrations in Lactating Women from Coastland, Lakeland, and Inland Areas of China

We aimed to assess the correlation between docosahexaenoic acid (DHA) dietary intake and the plasma, erythrocyte and breast milk DHA concentrations in lactating women residing in the coastland, lakeland and inland areas of China. A total of 408 healthy lactating women (42 ± 7 days postpartum) were recruited from four hospitals located in Weihai (coastland), Yueyang (lakeland) and Baotou (inland) city. The categories of food containing DHA, the average amount consumed per time and the frequency of consumption in the past month were assessed by a tailored DHA food frequency questionnaire, the DHA Intake Evaluation Tool (DIET). DHA dietary intake (mg/day) was calculated according to the Chinese Food Composition Table (Version 2009). In addition, fasting venous blood (5 mL) and breast milk (10 mL) were collected from lactating women. DHA concentrations in plasma, erythrocyte and breast milk were measured using capillary gas chromatography, and were reported as absolute concentration (μg/mL) and relative concentration (weight percent of total fatty acids, wt. %). Spearman correlation coefficients were used to assess the correlation between intakes of DHA and its concentrations in biological specimens. The study showed that the breast milk, plasma and erythrocyte DHA concentrations were positively correlated with DHA dietary intake; corresponding correlation coefficients were 0.36, 0.36 and 0.24 for relative concentration and 0.33, 0.32, and 0.18 for absolute concentration (p < 0.05). The median DHA dietary intake varied significantly across areas (p < 0.05), which was highest in the coastland (24.32 mg/day), followed by lakeland (13.69 mg/day), and lowest in the inland (8.84 mg/day). The overall relative and absolute DHA concentrations in breast milk were 0.36% ± 0.23% and 141.49 ± 107.41 μg/mL; the concentrations were significantly lower in inland women than those from coastland and lakeland. We conclude that DHA dietary intake is positively correlated with DHA concentrations in blood and breast milk in Chinese lactating women, suggesting that the tailored DHA food frequency questionnaire, DIET, is a valid tool for the assessment of DHA dietary intake.

Modifying effects of maternal Hb concentration on infant birth weight in women receiving prenatal iron-containing supplements: a randomised controlled trial

Concerns have been raised about the benefits of Fe-containing supplements on infant birth weight among women with normal/high Hb levels at baseline. Thus far, no clinical trials have examined whether the effects of prenatal Fe-containing supplements on birth weight vary by maternal Hb levels. We compared the effects of Fe-folic acid (IFA) or multiple micronutrients (MMN) with folic acid (FA) supplements on birth weight among pregnant women with mild/no anaemia or high Hb levels. A double-blind randomised controlled trial was conducted in 2006-2009. In total, 18 775 pregnant women with mild/no anaemia (145 g/l) baseline Hb levels, IFA and MMN supplements increased birth weight by 91·44 (95% CI 3·37, 179·51) g and 107·63 (95% CI 21·98, 193·28) g (P<0·05), respectively, compared with the FA group. No differences were found between the IFA and the MMN group, regardless of maternal Hb concentration. In conclusion, the effects of Fe-containing supplements on birth weight depended on baseline Hb concentrations. The Fe-containing supplements improved birth weight in women with very high Hb levels before 20 weeks of gestation.

Maternal severe stressful life events and risk of neural tube defects among rural Chinese

BACKGROUND Several human studies suggested an association between maternal stressful life events and increased risk of neural tube defects (NTDs). All of these studies, however, are from the United States; little was known among populations in developing countries that have different social and economic status. METHODS We examined the association between occurrence of maternal severe stressful life events during the periconceptional period and risk of NTDs in a population-based case-control study in Shanxi Province, China. Participants included 631 NTD cases (285 with anencephaly, 297 with spina bifida, and 49 with encephalocele) and 862 normal controls born between 2002 and 2007. Exposure information was collected within 1 week after delivery. The multivariable logistic regression model was used to estimate the adjusted odds ratio (OR) and its 95% confidence interval (95% CI) controlling for potential confounding variables. RESULTS Occurrence of maternal severe stressful life events was associated with a crude OR of 6.3 (95% CI, 2.8-14.4) for NTDs. After adjustment for all potential variables, the adjusted OR for NTDs remain significant (adjusted OR, 4.2; 95% CI, 1.4-12.6), and stronger for anencephaly (adjusted OR, 4.4; 95% CI, 1.2-15.9) than for spina bifida (adjusted OR, 3.4; 95% CI, 0.9-12.7). Adjustment for lifestyle variables greatly reduced the risk by 32%. A significant difference was found for some lifestyle characteristics between women with and without severe life events. CONCLUSIONS This study confirmed the association between maternal stress and risk of NTDs that has been consistently reported in the United States. The effect may be the combined results of maternal physiologic changes and lifestyle changes.