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Women reporting any heat exposure(saune,hot tub,fever,or electric blanket) in early pregnancy had a crude risk of their fetuses developing NTD of 1.6 (95%CI(confidence interval),0.9 to 2.9).Women reporting exposure to saune, hot tub,or fever in early pregnancy had a crude risk of their fetuses developing NTD 2.2 times that of women without heat exposure(95%CI 1.2 to 4.1).For hot tub use,the crude RR was 2.9(95%CI,1.4 to 6.3);for sauna,2.6 (95%CI,0.7 to 10.0);for fever,1.9(95%CI,0.8 to 4.1);and for electric blanket,1.2(95%CI,0.5 to 2.6).Multivariate adjusted RRs for individual heat sources,after controlling for maternal age,folic acid supplements, family history of NTD,and exposure to other heat sources,were for hot tub use,2.8(95%CI,1.2 to 6.5);sauna,1.8(95%CI,0.4 to 7.9);fever,1.8(95%CI,0.8 to 1.4);and electric blanket,1.2(95%CI,0.5 to 2.6).When only hot tub, saune,and fever were considered and the women's exposure to each tallied, compared with no heat exposure,the RR for NTDs increased from 1.9(95%CI,0. 9 to 3.7)after ne type of heat exposure to 6.2(95%CI,2.2 to 17.2)after two types of heat exposure.Conclusions.-Exposure to heat in the form of hot tub,sauna,or fever in the first trimester of pregnancy was associated with an increased risk for NTDs.Hot tub exposure appeared to have the strongest effect of any single heat exposure.Exposure to electric blanket was not materailly association with increased risk for NTDs. |
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