Association between early spontaneous abortion and homocysteine metabolism.

Objective: The purpose of this study is to explore the effects of homocysteine (HCY) metabolism and related factors on early spontaneous abortion. Methods: We conducted a hospital-based case-control study and included a total of 500 cases and 1,000 controls in Shaanxi China. Pregnant women waiting for delivery in the hospital were interviewed to report their characteristics and other relevant information during pregnancy. The unconditional Logisitic regression model was applied to assess the association between early spontaneous abortion and HCY metabolism and related factors. The multiplicative model was applied to assess the effects of interaction of HCY metabolism and related factors on early spontaneous abortion. The logit test method of generalized structural equation model (GSEM) was used to construct the pathway diagram of HCY metabolism and related factors affecting early spontaneous abortion. Results: Folic acid supplementation and adequate folic acid supplementation during periconception were the protective factors of early spontaneous abortion (OR = 0.50, 95% CI: 0.38-0.65; OR = 0.44, 95% CI: 0.35-0.54). The serum folate deficiency, higher plasma HCY in early pregnancy, the women who carried the MTHFR 677TT genotype were the risk factors of early spontaneous abortion (OR = 5.87, 95% CI: 1.53-22.50; OR = 2.94, 95% CI: 1.14-7.57; OR = 2.32, 95% CI: 1.20-4.50). The women's educational level and maternal and child health care utilization affected the occurrence of early spontaneous abortion by influencing the folic acid supplementation during periconception. The folic acid supplementation during periconception affected the occurrence of early spontaneous abortion by influencing the level of serum folate or plasma HCY in early pregnancy. The maternal MTHFR 677 gene polymorphism affected the occurrence of early spontaneous abortion by influencing the level of serum folate in early pregnancy. In terms of the risks for early spontaneous abortion, there was multiplicative interaction between higher plasma HCY in early pregnancy, serum folate deficiency in early pregnancy and maternal MTHFR 677TT genotype (OR = 1.76, 95% CI: 1.17-4.03), and there was multiplicative interaction between higher plasma HCY and serum folate deficiency in early pregnancy (OR = 3.46, 95% CI: 2.49-4.81), and there was multiplicative interaction between serum folate deficiency in early pregnancy and maternal MTHFR 677TT genotype (OR = 3.50, 95% CI: 2.78-5.18). The above interactions are all synergistic. The occurrence risk of early spontaneous abortion was significantly increased if multiple factors existed at the same time. Conclusion: Our study is the first time to construct the pathway of HCY metabolism and related factors affecting early spontaneous abortion, and provides a comprehensively new idea to prevent and reduce the occurrence of spontaneous abortion.

Association of antenatal vitamin B complex supplementation with neonatal vitamin B12 status: evidence from a cluster randomized controlled trial.

PURPOSE: Evidence about the effect of maternal vitamin B12 supplementation on offspring's vitamin B12 status is limited. The present interventional study sought to evaluate the association of antenatal vitamin B complex supplementation with neonatal vitamin B12 status. METHODS: In an ongoing cluster randomized controlled trial conducted in three rural counties in northwest China, pregnant women < 20 weeks of gestation were randomized to three treatment groups: blank control, iron supplements, or vitamin B complex supplements. All women were administered folic acid supplements during the periconceptional period. In a sub-study, we collected cord blood samples of 331 participants from the control or vitamin B complex groups in the Xunyi county from January 2017 to December 2017. Plasma concentrations of folate, vitamin B12, and homocysteine were measured. Linear mixed models with a random intercept for cluster were used to compare biochemical indexes between groups after controlling for covariates. RESULTS: Compared with newborns whose mothers were in the control group, newborns of the vitamin B complex-supplemented women had significantly higher cord plasma vitamin B12 (P = 0.001) and lower homocysteine concentrations (P = 0.043). The association of antenatal vitamin B complex supplementation with cord blood vitamin B12 concentrations appeared to be more pronounced among newborns with high folate status than those with low folate status (Pinteraction = 0.060). CONCLUSIONS: Maternal vitamin B complex supplementation during pregnancy was associated with better neonatal vitamin B12 status in rural northwest China.

Associations between maternal calcium intake from diet and supplements during pregnancy and the risk of preterm birth in a Chinese population.

BACKGROUND/OBJECTIVES: Preterm birth is a global public health priority related to maternal nutrition. The effect of maternal calcium intake during pregnancy on preterm birth is inconclusive and data is lacking in China. We aimed to estimate the role of calcium intake from diet and supplements on preterm birth in the Chinese population. METHODS: We used data of 7195 women from a large-scale cross-sectional study in Northwest China. Dietary intake was evaluated via a validated food frequency questionnaire, and other information was collected by a structured questionnaire. Generalized estimating equation models were used to estimate the relationship between calcium intake and preterm birth. RESULTS: Inadequate dietary calcium intake was universal in our population (85.9%), and no association was found between daily dietary calcium intake and preterm birth. Maternal calcium supplementation was significantly associated with reduced risk of preterm birth (OR 0.72, 95% CI 0.60, 0.87, P = 0.001), particularly among women who commenced calcium supplementation in the second and third trimester of pregnancy with longer duration (OR 0.62, 95% CI 0.42, 0.91, P = 0.015). Higher daily calcium intake from supplements was linked with lower preterm birth risk (every 100 mg increase: OR 0.87, 95% CI 0.79, 0.96, P = 0.004). There is a negative association between daily total calcium intake and preterm birth among calcium supplement users (every 100 mg increase: OR 0.91, 95% CI 0.84, 0.97, P = 0.007). CONCLUSIONS: In conclusion, appropriate calcium supplementation during pregnancy could be beneficial in the prevention of preterm birth, and it might be suitable for implementing in low calcium intake areas of China.

Parameterization of the mid-trimester drop in blood pressure trajectory during pregnancy and its utility for predicting preeclampsia.

OBJECTIVES: The purpose of this study was to parameterize mid-trimester drop in blood pressure (BP) trajectory during pregnancy and to evaluate its utility for predicting preeclampsia. METHODS: To develop parametric models for BP trajectory during pregnancy, we used data from 7923 Chinese pregnant women with 24 810 routine antenatal care visits. Then, we evaluated the utility of BP trajectory parameters for predicting clinician-diagnosed preeclampsia in a separate sample of 3524 pregnant women from a randomized controlled trial of prenatal vitamin supplementation conducted in the same area. We focused on parameters related to the mid-trimester BP drop, including the gestational age and BP value at the nadir (lowest point), change in BP, velocity, and area under curve during two periods (from 12 weeks of gestation to the nadir and from the nadir to 33 weeks of gestation). RESULTS: All participants in our analysis had a mid-pregnancy drop in their SBP, DBP, and mean arterial pressure (MAP) trajectories. There were high correlations (|r| > 0.90) among trajectory parameters of the same BP measure. The final prediction model included selective parameters of SBP, DBP, and MAP trajectories, prepregnancy BMI and gestational age at the first antenatal care visit. The area under the receiver-operating curve for predicting preeclampsia was 0.886 (95% confidence interval 0.846--0.926) in the training dataset and 0.802 (0.708--0.895) in the validation dataset. CONCLUSION: Our novel BP trajectory parameters are informative and can predict preeclampsia at a clinically acceptable level.

Maternal adherence to micronutrient supplementation before and during pregnancy in Northwest China: a large-scale population-based cross-sectional survey.

OBJECTIVES: To report the situation of maternal micronutrient supplementation before and during pregnancy in Northwest China and to examine the rates of and factors related to the adherence to micronutrient supplementation among pregnant women in this region, where dietary micronutrient intake is commonly insufficient. DESIGN: A large-scale population-based cross-sectional survey. SETTING: Twenty counties and ten districts of Shaanxi Province. PARTICIPANTS: A sample of 30 027 women were selected using a stratified multistage random sampling method. A total of 28 678 women were chosen for the final analysis after excluding those who did not provide clear information about nutritional supplementation before and during pregnancy. MAIN OUTCOME MEASURES: Maternal adherence to micronutrient supplementation (high and low) were the outcomes. They were determined by the start time and duration of use according to Chinese guidelines (for folic acid (FA) supplements) and WHO recommendations (for iron, calcium and multiple-micronutrient (MMN) supplements). RESULTS: In total, 83.9% of women took at least one kind of micronutrient supplement before or during pregnancy. FA (67.6%) and calcium (57.5%) were the primarily used micronutrient supplements; few participants used MMN (14.0%) or iron (5.4%). Adherence to supplementation of all micronutrients was low (7.4% for FA, 0.6% for iron, 11.7% for calcium and 2.7% for MMN). Higher educational levels, higher income levels, urban residence and better antenatal care (including pregnancy consultation and a higher frequency of antenatal visits) were associated with high adherence to micronutrient supplementation. CONCLUSION: Maternal micronutrient supplementation before and during pregnancy in Northwest China was way below standards recommended by the Chinese guidelines or WHO. Targeted health education and future nutritional guidelines are suggested to improve this situation, especially in pregnant women with disadvantaged sociodemographic conditions.

The association of maternal dietary folate intake and folic acid supplementation with small-for-gestational-age births: a cross-sectional study in Northwest China.

The effect of maternal folate intake on small-for-gestational-age (SGA) births remains inconclusive. The present study aimed to investigate the associations of maternal folate intake from diet and supplements with the risk of SGA births using data from a cross-sectional study in Shaanxi Province of Northwest China. A total of 7307 women who were within 12 months (median 3; 10th-90th percentile 0-7) after delivery were included. Two-level models were adopted to examine the associations of folate (dietary folate, supplemental folic acid and total folate) intake with the risk of SGA births and birth weight Z score, controlling for a minimum set of confounders that were identified in a directed acyclic graph. Results showed that a higher supplemental folic acid intake during the first trimester was negatively associated with the risk of SGA births (≤60 d v. non-use: OR 0·80; 95 % CI 0·66, 0·96; >60 d v. non-use: OR 0·78; 95 % CI 0·65, 0·94; Ptrend = 0·010; per 10-d increase: OR 0·97; 95 % CI 0·95, 0·99). A higher total folate intake during pregnancy was associated with a reduced risk of SGA births (highest tertile v. lowest tertile: OR 0·77; 95 % CI 0·64, 0·94; Ptrend = 0·010; per one-unit increase in the log-transformed value: OR 0·81; 95 % CI 0·69, 0·95). A similar pattern was observed for the birth weight Z score. Our study suggested that folic acid supplementation during the first trimester and a higher total folate intake during pregnancy were associated with a reduced risk of SGA births.

A propensity-matched study of the association between optimal folic acid supplementation and birth defects in Shaanxi province, Northwestern China.

The association between folic acid supplementation and birth defects other than neural tube defects remains unclear. We utilized data from a large population-based survey to examine the association between folic acid supplementation and birth defects in Northwestern China. A total of 29,204 women with infants born between 2010 and 2013 were surveyed in Shaanxi province, Northwestern China, using a stratified multistage sampling method. Propensity scores were used to match 9,293 women with optimal folic acid supplementation with 9,293 women with nonoptimal folic acid supplementation, and the effects of optimal folic acid supplementation on birth defects were assessed by a conditional logistic regression model. After propensity score matching, the overall birth defect rate, cardiovascular system defect rate and nervous system defect rate for the women with optimal folic acid supplementation were lower than those for the women with nonoptimal folic acid supplementation (overall birth defects: OR = 0.71, 95% CI = 0.57-0.89, P = 0.003; cardiovascular system defects: OR = 0.65, 95% CI = 0.44-0.96, P = 0.032; nervous system defects: OR = 0.13, 95% CI = 0.02-0.99, P = 0.049). Optimal folic acid supplementation was associated with a decreased prevalence of birth defects, especially in the cardiovascular system and nervous system. Our findings have important implications for birth defect intervention with folic acid supplementation for countries with a high prevalence of birth defects, such as China.

Maternal iron intake during pregnancy and birth outcomes: a cross-sectional study in Northwest China.

Previous studies have yielded conflicting results on the associations of maternal Fe intake with birth outcomes. This study aimed to investigate the associations between maternal Fe intake (total Fe from diet and supplements, dietary total Fe, haeme Fe, non-haeme Fe and Fe supplements use) and adverse birth outcomes in Shaanxi Province of Northwest China. In all, 7375 women were recruited using a stratified multistage random sampling method at 0-12 months (median 3; 10th-90th percentile 0-7) after delivery. Diets were collected by a validated FFQ and maternal characteristics were obtained via a standard questionnaire. The highest tertile of haeme Fe intake compared with the lowest tertile was negatively associated with low birth weight (LBW) (OR 0·68; 95 % CI 0·49, 0·94), small for gestational age (SGA) (OR 0·76; 95 % CI 0·62, 0·94) and birth defects (OR 0·55; 95 % CI 0·32, 0·89). Maternal haeme Fe intake was associated with a lower risk of intra-uterine growth retardation (IUGR) (medium tertile v. lowest tertile: OR 0·78; 95 % CI 0·61, 0·95; highest tertile v. lowest tertile: OR 0·76; 95 % CI 0·59, 0·93; P trend=0·045). The OR of LBW associated with Fe supplements use were as follows: during pregnancy: 0·72 (95 % CI 0·50, 0·95); in the second trimester: 0·67 (95 % CI 0·42, 0·98); in the third trimester: 0·47 (95 % CI 0·24, 0·93). We observed no associations of total Fe, dietary total Fe or non-haeme Fe intake with birth outcomes. The results suggest that maternal haeme Fe intake is associated with a reduced risk of LBW, SGA, IUGR and birth defects, and Fe supplements use during pregnancy reduces LBW risk.