Fever during pregnancy and spontaneous abortion.

The hypothesis that maternal fever during pregnancy is a risk factor for spontaneous abortion was tested in a case-control study by comparing the frequencies and timing of fevers of 100 F (37.78 C) or more among three groups of women: women having euploid abortions, women having aneuploid abortions, and women delivering at 28 weeks gestation or later (controls). Cases and controls were identified in three New York City hospitals between August 1979 and June 1982. It was hypothesized that if fever was an antecedent, rather than a symptom of spontaneous abortion, an association would be detected with euploid but not with aneuploid abortions. Among public patients, reported fevers were significantly more frequent among euploid abortions than among controls (18% vs. 7.1%, odds ratio = 2.96), whereas reported fevers were not more frequent among aneuploid abortions (3.9% vs. 7.1%, odds ratio = 0.52). It was also postulated that variation in the strength of the association of fever with euploid abortion with the duration of the interval between the fever and the abortion might yield insight about mechanisms underlying an association. The odds ratios for fever occurring at three intervals--in the same calendar month as a euploid abortion, one month before, and two or more months before--were 6.04, 3.28, and 1.41, respectively. The findings for private patients--for whom a control group was not recruited--are compatible with those for public patients although not statistically significant: the odds of fever with euploid abortion were 2.18 times those with aneuploid abortion.