Yali Zhang1,2, Zhiwen Li1,2, Le Zhang1,2, Jufen Liu1,2, Lei Jin1,2, Aiguo Ren1,2. 1. Institute of Reproductive and Child Health/Key Laboratory of Reproductive Health, National Health and Family Planning Commission of the People's Republic of China, Peking University, Beijing 100191, People's Republic of China. 2. Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, People's Republic of China.
Abstract
BACKGROUND: This study assessed the association between severe NVP and the risk of NTD in offspring compared with a population and a malformed control group. We also assessed whether folic acid supplements modified this association. STUDY DESIGN AND SETTING: A case-control study was conducted with subjects enrolled from June 19, 2002, to November 18, 2014, from a population-based birth defects surveillance system that monitors major external structural birth defects through active case ascertainment in Shanxi Province, China. The main comparison was between women with NTD-affected offspring who experienced NVP in early pregnancy versus those who did not. A multivariable logistic regression model was used to examine the associations between severe NVP and the risk of NTD while adjusting for potential confounding factors. The risk was estimated by calculating the odds ratio (OR) and 95% confidence intervals (CIs). RESULTS: The adjusted OR (AOR) of severe NVP for NTDs was 3.25 (95%CI 2.56, 4.12) compared with the population control, and 1.65 (95%CI 1.00, 2.72) compared with the malformed controls. When stratified by intake of folic acid supplements, the AOR for severe NVP was 3.40 (95%CI 2.61, 4.42) in the non-intake of folic acid supplements stratum and 2.51 (95%CI 1.42, 4.43) in the intake of folic acid supplements stratum. CONCLUSION: We conclude that severe NVP is associated with NTDs, and that severe NVP may be a consequence, rather than a cause, of NTDs.
BACKGROUND: This study assessed the association between severe NVP and the risk of NTD in offspring compared with a population and a malformed control group. We also assessed whether folic acid supplements modified this association. STUDY DESIGN AND SETTING: A case-control study was conducted with subjects enrolled from June 19, 2002, to November 18, 2014, from a population-based birth defects surveillance system that monitors major external structural birth defects through active case ascertainment in Shanxi Province, China. The main comparison was between women with NTD-affected offspring who experienced NVP in early pregnancy versus those who did not. A multivariable logistic regression model was used to examine the associations between severe NVP and the risk of NTD while adjusting for potential confounding factors. The risk was estimated by calculating the odds ratio (OR) and 95% confidence intervals (CIs). RESULTS: The adjusted OR (AOR) of severe NVP for NTDs was 3.25 (95%CI 2.56, 4.12) compared with the population control, and 1.65 (95%CI 1.00, 2.72) compared with the malformed controls. When stratified by intake of folic acid supplements, the AOR for severe NVP was 3.40 (95%CI 2.61, 4.42) in the non-intake of folic acid supplements stratum and 2.51 (95%CI 1.42, 4.43) in the intake of folic acid supplements stratum. CONCLUSION: We conclude that severe NVP is associated with NTDs, and that severe NVP may be a consequence, rather than a cause, of NTDs.