Hot flashes during the third trimester are completely normal and very common. The combination of surging hormones, increased blood volume, and the physical strain of carrying a growing baby all contribute to sudden waves of heat that can leave you flushed and sweaty. While they can be uncomfortable and sometimes alarming, hot flashes in late pregnancy are typically harmless and temporary.
Why Hot Flashes Happen in Late Pregnancy
Throughout pregnancy, your levels of estrogen and progesterone rise dramatically. These surges directly affect your hypothalamus, the part of your brain that acts as your body’s thermostat. When hormonal shifts throw off this internal temperature gauge, your brain can mistakenly signal that you’re overheating, triggering a hot flash to cool you down. It’s the same basic mechanism behind menopausal hot flashes, just driven by rising hormones instead of falling ones.
In the third trimester specifically, the cause may go beyond hormones alone. Your body is working harder to support a full-sized baby. Your heart is pumping significantly more blood, your metabolism is running faster, and you’re carrying extra weight that generates more body heat. All of this compounds the hormonal effect, which is why many women experience hot flashes for the first time in late pregnancy even if the first two trimesters were uneventful.
What They Feel Like
A pregnancy hot flash typically hits as a sudden wave of warmth spreading across your chest, neck, and face. Your skin may flush red, and you might break into a sweat that lasts anywhere from 30 seconds to a few minutes. Some women feel their heart rate pick up slightly. Night sweats are the same phenomenon occurring during sleep, and they can be intense enough to soak through pajamas or sheets.
The episodes tend to come and go unpredictably. You might have several in one day and then none for a week. Common triggers include warm rooms, physical activity, spicy food, and stress, though they can also strike with no obvious cause at all.
When Heat Means Something Else
The key distinction is between feeling hot and having a fever. Hot flashes don’t raise your core body temperature. A true fever, generally 100.4°F (38.0°C) or higher, can signal an infection that needs medical attention. A sustained fever above 102°F (38.9°C) is particularly concerning in pregnancy.
It’s also worth paying attention to symptoms that accompany the heat. A hot flash on its own is benign. But if you notice sudden swelling in your face or hands, a severe headache that won’t go away, visual changes like seeing spots, or persistent upper abdominal pain alongside feeling overheated, these could point to a blood pressure complication like preeclampsia rather than a simple hot flash. The heat itself isn’t the red flag in those cases; the other symptoms are.
Practical Ways to Cool Down
You can’t eliminate hot flashes entirely while pregnant, but you can make them shorter and less miserable. A few strategies that help:
- Dress in layers. Lightweight, breathable fabrics let you peel off a layer the moment a flash starts. Natural fibers like cotton work better than synthetics.
- Keep cold water nearby. Drinking ice water or splashing it on your face and wrists can cut a hot flash short. A damp, cool washcloth on the back of your neck works well too.
- Stay hydrated. Replenish fluids throughout the day, especially if you’re sweating heavily. Adding electrolytes helps if sweating is frequent.
- Time your exercise. Work out during cooler parts of the day or move your routine into an air-conditioned space. Overheating during exercise can intensify and prolong hot flashes.
- Use breathing techniques. Slow, controlled breathing can actually help regulate your body temperature during a flash. Deep inhales through the nose and slow exhales through the mouth activate your body’s built-in cooling response.
- Adjust your sleep setup. If night sweats are the main problem, try moisture-wicking sheets, a fan pointed at the bed, or keeping your bedroom a few degrees cooler than usual.
What Happens After Delivery
Don’t be surprised if hot flashes and night sweats continue, or even get worse, after your baby is born. The dramatic plunge in estrogen and progesterone that follows delivery triggers the same thermoregulatory confusion, this time from hormone withdrawal rather than hormone surges. Postpartum night sweats tend to peak during the first two weeks after birth and typically resolve on their own within a few weeks as your hormones stabilize.
If you’re breastfeeding, the sweating may linger longer. Prolactin, the hormone that drives milk production, keeps estrogen levels suppressed, which extends the period of temperature regulation disruption. Postpartum sweating that persists beyond three weeks is worth mentioning to your provider, as it can occasionally signal a thyroid issue or infection rather than normal hormonal adjustment.