The effect of fever, febrile illnesses, and heat exposures on the risk of neural tube defects in a Texas-Mexico border population.
BACKGROUND
Hyperthermia produces neural tube defects (NTDs) in a variety of animal species. Elevated maternal body temperatures may also place the developing human embryo at risk. We examined the relation between maternal hyperthermia and the development of NTDs in a high-risk Mexican-American population.


METHODS
Case-women were Mexican-American women with NTD-affected pregnancies who resided and delivered in any of the 14 Texas counties bordering Mexico, during 1995-2000. Control-women were randomly selected from study area residents delivering normal live births, frequency-matched to cases by hospital and year. Information on maternal fevers, febrile illnesses, exposures to heat generated from external sources, and hyperthermia-inducing activities was gathered through in-person interviews, conducted about six weeks postpartum.


RESULTS
The risk effect (OR) associated with maternal fever in the first trimester, compared to no fever, was 2.9 (95% CI, 1.5-5.7). Women taking fever-reducing medications showed a lower risk effect (OR, 2.4; 95% CI, 1.0-5.6) than those who did not (OR, 3.8; 95% CI, 1.4-10.9). First-trimester maternal exposures to heat devices such as hot tubs, saunas, or electric blankets were associated with an OR of 3.6 (95% CI, 1.1-15.9). Small insignificant effects were observed for activities such as cooking in a hot kitchen (OR, 1.6; 95% CI, 1.0-2.6) and working or exercising in the sun (OR, 1.4; 95% CI, 0.9-2.2).


CONCLUSIONS
Maternal hyperthermia increases the risk for NTD-affected offspring. Women intending to become pregnant should avoid intense heat exposures, carefully monitor and manage their febrile illnesses, and routinely consume folic acid supplements.
Suarez
Lucina
L
Epidemiology Research Services, Texas Department of Health, Austin, Texas 78756-3199, USA. lucina.suarez@tdh.state.tx.us
Felkner
Marilyn
M
Hendricks
Kate
K
D000328:Adult; D005260:Female; D005334:Fever / Q000150:complications*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008800:Mexico; D009436:Neural Tube Defects / Q000453:epidemiology / Q000209:etiology*; D011247:Pregnancy; D012307:Risk Factors; D013781:Texas