Night sweats during pregnancy

By trimester

Weeks 1–13

1st trimester

Night sweats often show up early, in the first trimester, as progesterone rises quickly and shifts your body's internal temperature set point warmer, alongside a plasma volume increase that brings more blood flow near the skin.

Weeks 14–27

2nd trimester

Many people notice night sweats ease up somewhat in the second trimester as hormone levels stabilize, though your resting metabolic rate keeps climbing to support your growing baby and placenta.

Weeks 28–birth

3rd trimester

Night sweats commonly return or intensify in the third trimester, when metabolic heat production from the pregnancy is at its highest and your body is working hardest to move that extra heat away overnight.

What does the evidence show for night sweats?

• Pregnancy comes with several heat-related adaptations working at once: a lower threshold for when you start sweating, increased blood flow near the skin, and more plasma volume, alongside a higher rate of internal heat production from the metabolic work of growing the placenta and baby. 1
• Progesterone shifts the body's internal temperature set point toward warmer, and receptors for progesterone and estrogen sit in the same part of the brain, the hypothalamic preoptic area, that regulates temperature-sensitive neurons, which helps explain why rising pregnancy hormones can make you feel warmer and sweat more at night. 2
• These same physiological shifts, including a higher metabolic rate and changes in how efficiently the body sheds heat under strain, are part of why pregnant people are considered more vulnerable to heat-related symptoms generally, not just at night. 3
• A fever is a rise in body temperature over 101°F (38.3°C), and a prolonged fever, especially one left unaddressed in the first 12 weeks, is linked to a small increased chance of certain birth defects, which is why night sweats paired with an actual fever are worth mentioning to your provider rather than assuming it's routine pregnancy warmth. 4
• Short, controlled heat exposure, like a warm bath, is generally well tolerated in pregnancy because these compensatory mechanisms work effectively over brief periods, though prolonged heat exposure in hot environments is less well studied. 1

When should I call my provider about night sweats?

Night sweats alone, without other symptoms, are rarely a concern. A true fever over 101°F (38.3°C), especially alongside chills, feeling unusually unwell, pain, or a rapid heartbeat, points toward a possible infection rather than ordinary pregnancy warmth and is worth a same-day call to your provider. A fever left unaddressed, particularly early in pregnancy, has also been linked to a small increased chance of certain birth defects, so it's worth addressing with your provider and reporting rather than waiting it out. When in doubt, call your obstetric team the same day. Early input almost always beats waiting, and the on-call line exists exactly for this.