Prospective evaluation of nighttime hot flashes during pregnancy and postpartum

Objective: To determine the prevalence, course, and risk factors for nighttime hot flashes during the pregnancy and postpartum periods.

Design: Clinical interview, physical measurements, and questionnaires administered at weeks 20, 30, and 36 of pregnancy and weeks 2, 12, 26, and 52 after delivery.

Setting: Academic medical setting.

Patient(s): 429 women.

Intervention(s): None.

Main outcome measure(s): Nighttime hot flashes.

Result(s): Thirty-five percent of women reported nighttime hot flashes during pregnancy and 29% after delivery. In multivariable binomial mixed effects models, women who were younger (per year: odds ratio [OR] 0.94; 95% confidence interval [CI], 0.88-0.99), had a higher prepregnancy body mass index (per unit increase: OR 1.05; 95% CI, 1.01-1.10), and had less than a college education (OR 2.58; 95% CI, 1.19-5.60; vs. ≥ college) were more likely to report nighttime hot flashes during pregnancy. Higher depressive symptoms were associated with nighttime hot flashes during pregnancy (per unit increase: OR 1.08; 95% CI, 1.04-1.13) and the postpartum period (OR 1.19; 95% CI, 1.14-1.25, multivariable models).

Conclusion(s): Hot flashes, typically considered a menopausal symptom, were reported by over a third of women during pregnancy and/or the postpartum period. The predictors of these hot flashes, including depressive symptoms, low education, and higher body mass index are similar to those experienced during menopause. Future work should investigate the role of hormonal and affective factors in hot flashes during pregnancy and postpartum.