Snoring is common in pregnancy, and snoring pregnant women have increased rates of pre-eclampsia. Patients with pre-eclampsia show upper airway narrowing during sleep. The present study aimed to compare upper airway dimensions in pregnant and nonpregnant women and in patients with pre-eclampsia. A total of 50 women in the third trimester of pregnancy and 37 women with pre-eclampsia were recruited consecutively from the antenatal service and matched with 50 nonpregnant women. Upper airway dimensions were measured using acoustic reflection. Comparisons were made by analysis of variance and Student-Newman-Keuls tests. Snoring was reported by 14% of nonpregnant women, 28% of pregnant women, and 75% of pre-eclamptic women (p < 0.001). When seated, pregnant women had wider upper airways than nonpregnant women (p < 0.02), but there was no difference when supine. Oropharyngeal junction area in the seated position was less (p < 0.01) in the women with pre-eclampsia (mean +/- SD: 0.9 +/- 0.1 cm2) than either nonpregnant (1.1 +/- 0.1 cm2) or pregnant women (1.3 +/- 0.1 cm2). Supine oropharyngeal junction area was less in the women with pre-eclampsia than in the nonpregnant women (0.8 +/- 0.1 versus 1.0 +/- 0.1 cm2; p = 0.01) but similar in women with pre-eclampsia and pregnant women (0.9 +/- 0.1 cm2; p > 0.3). The study showed that women with pre-eclampsia have upper airway narrowing in both upright and supine postures. These changes could contribute to the upper airway resistance episodes during sleep in patients with pre-eclampsia, which may further increase their blood pressure.