Background: Physical and hormonal changes during pregnancy alter breathing patterns of pregnant women. It is possible that occult disordered breathing during sleep may be a risk factor for the development of pregnancy-induced hypertension (PIH) and preeclampsia. Objective: Our aim was to determine the incidence of self-reported snoring in pregnant women, and to investigate the relationship of snoring, obesity and neck circumference to PIH and preeclampsia. Methods: 469 pregnant women and 208 age-matched nonpregnant women were included in the study. Both groups were asked to complete a questionnaire. Maternal complications were retrieved from the medical records. Results: Habitual snoring was reported from 1.9% of nonpregnant women, 2.5% of pregnant women prior to pregnancy and 11.9% of those same women during the third trimester of pregnancy (p < 0.001). Age, smoking during pregnancy, and weight before delivery were independent risk factors for habitual snoring in pregnancy. PIH and preeclampsia developed in 20 and 10.9% of pregnant women with habitual snoring, as compared to 11 and 5.8% of non-snoring pregnant women (p = 0.045, p = 0.125, p = 0.415), respectively. In women who developed preeclampsia, weight before preg nancy, weight before delivery and neck circumference were significantly higher in univariate analysis. Neck circumference was an independent risk factor for PIH and preeclampsia according to logistic regression analysis. Conclusion: The incidence of snoring is significantly higher in pregnant women than in nonpregnant women. Snoring may indicate a risk of PIH. Neck circumference was an independent risk factor for both PIH and preeclampsia. Copyright (C) 2007 S. Karger AG, Basel.