A population-based case-control study of risk factors for neural tube defects in Shenyang, China

To explore the risk factors for neural tube defects (NTD) in Shenyang, we carried out a population-based case-control study. We used chi-square test or Fisher's exact test to evaluate variations in the prevalence by selected covariates. Adjusted odds ratios and 95% confidence intervals were derived from univariate and multivariable conditional logistic models. A history of maternal previous birth defect-affected pregnancy was a risk factor for NTDs (adjusted OR = 4.00, 95%CI = 1.29-12.45). Risks for NTDs were significantly associated with exposure to maternal factors during the periconceptional period such as a history of fever or cold (adjusted OR = 6.36, 95%CI = 3.24-12.52), use of analgesic and antipyretic drugs (adjusted OR = 4.94, 95%CI = 1.79-13.63), oral contraceptive use (adjusted OR 2.06, 95%CI 1.16, 3.68), and passive smoking (adjusted OR = 2.24, 95%CI = 1.04-4.81). Folic acid tablets use and fresh vegetable or fruit consumption a parts per thousand yen6 meals a week in periconception appeared to be protective factors (adjusted OR 0.33, 0.55, and 0.40, and 95%CI 0.13-0.44, 0.30-1.01, and 0.21-0.74, respectively). Differences in risk were found between the two most common phenotypes of NTD, anencephaly, and spina bifida. This study suggests that a history of previous birth defect-affected pregnancy, a history of maternal fever or cold, use of analgesics, antipyretics, and oral contraceptives, exposure to passive smoking, folic acid use, and consumption of fresh vegetable and fruit may be associated with NTD risk.