Physical Activity and Risk of Neural Tube Defects

Abstract

Reports that physical activity is associated with risk factors for neural tube defects (NTDs), including obesity, nutrient intake, socioeconomic status, and race/ethnicity, prompted the present population-based, case-control study relating maternal activity levels before pregnancy to NTD risk. The study group consisted of 538 women whose infants or fetuses had anencephaly, spina bifida cystica, craniorachischisis, or iniencephaly and who had in-person interviews. Mothers of 539 infants with no malformations were also interviewed within 5 months after term delivery. An index of periconceptional activity was based on the reported frequency and exertional level in several areas, such as jogging/ running, active sports, physical exercises. swimming or long walks, and such activities as gardening and fishing. Compared with control women, study cases were less likely to have taken multivitamin/mineral supplements at about the time of conception, and they were more likely to be foreign-born Latinas, obese, and to have less than a high school education. Frequent vigorous activity of any type correlated with a reduced risk of NTDs, as did higher scores on the physical activity index. On multivariate logistic regression analysis, physical activity correlated with NTD risk in women who had not taken multivitamin/mineral supplements in the periconceptional period. For women who did take supplements, physical activity was associated with either a less marked risk reduction or no reduction at all. Results analyzed for spina bifida and anencephaly resembled those obtained when all NTDs were grouped together. These findings indicate that for women who engage in any of a wide range of physical activities during the periconceptional period, their fetus or infant is less likely to have an NTD. This is especially the case for women who do not take multivitamin or mineral supplements at about the time of conception. It may be that physical activity serves as a marker for other health-related practices, such as weight control.