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October 29, 2019
By Kimberly Langdon, M.D., OB/GYN
Hot flashes (daytime sweats) and night sweats are the classic menopausal symptoms but can occur under other circumstances such as pregnancy and postpartum. Night sweats are associated with sleep disturbances, irritability, overall impairments in physical, social, and emotional aspects of life. Although the mechanism of hot flashes is not well understood, they are thought to be thermoregulatory events occurring due to the dramatic hormonal transitions experienced during the pregnancy, postpartum, and menopause transitions.
Surveys of pregnant women indicate that a large number of women experience hot flashes/night sweats, and 10% experience them postpartum. Another study showed that 35% of women have hot flashes during pregnancy and 29% have them postpartum. Postpartum, they peak in week two. However, no studies have tracked the frequency of hot flashes or the course throughout pregnancy and the postpartum period.
Any time the core body temperature increases, there is an increased chance of having a night sweat/hot flash. In pregnancy, the hormone progesterone is mostly responsible for increased heat production as is the growing baby. During the postpartum period, the rapid drop in estrogen triggers hot flashes and may continue during breastfeeding because the ovaries (which produce and release estrogen) are suppressed during lactation. If you start oral contraception that contains estrogen, the hot flashes should improve. However, unlike the progestin-only pill, pills containing estrogen are not recommended during breastfeeding.
Related: All about postpartum birth control
There are other probable factors in operation because not all women experience night sweats/hot flashes. The thermoregulatory system in the brain, nerve-hormone regulation,the nervous and blood vessel system also contribute to thermal regulation [1,2]. For instance, excess thyroid hormone can cause night sweats/hot flashes. Any persistent night sweats past the point of breastfeeding should be evaluated.
Related: Postpartum Thyroiditis
Other factors include smoking, depression, younger age, unemployment, lower educational levels, and obesity. Elevated depressive and anxious symptoms seem to be the most consistent predictor of hot flashes in pregnancy and the postpartum period. Elevated BMI may trigger hot flashes via the extra insulation or ability to dissipate heat through the skin.
Related: PMADs vs. Postpartum Depression
Postpartum night sweats typically peak around week two postpartum and gradually lessen over time. However, low estrogen triggers them, and breastfeeding causes estrogen levels to remain low, some report that hot flashes and night sweats continue until lactation ends.
Night sweats will go away on their own. However, in the meantime, there are things you can do to make yourself more comfortable.
Generally night sweats are not cause for concern. However, talk to your doctor if they do not improve over time or if you have any of the following symptoms:
Thurston R, Christie I, Matthews K. Hot flashes and cardiac vagal control during women’s daily lives. Menopause. 2012 Apr;19(4):406–12.
Thurston RC, Sutton-Tyrrell K, Everson-Rose SA, Hess R, Matthews KA. Hot flashes and subclinical cardiovascular disease: findings from the Study of Women’s Health Across the Nation Heart Study. Circulation. 2008 Sep 16;118(12):1234–40.
Thurston, R. C., Luther, J. F., Wisniewski, S. R., Eng, H., & Wisner, K. L. (2013). Prospective evaluation of nighttime hot flashes during pregnancy and postpartum. Fertility and sterility, 100(6), 1667–1672. doi:10.1016/j.fertnstert.2013.08.020
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