What causes night sweats during pregnancy—and how to find relief

When you’re creating a new human being, the body works pretty hard to meet your needs and your baby’s at the same time. Extra blood is made and hormones rise and fall suddenly, leaving you tired, nauseous, irritable, and—yes—hot and sweaty, even in the middle of the night. 

Night sweats (nocturnal hyperhidrosis) are a common occurrence for most adults: According to Teresa Hoffman, MD, an OB-GYN at Mercy Medical Center in Baltimore, your body temperature peaks around midnight and then drops to its lowest around 6 a.m.; when this drop happens dramatically (like going from 98.9 degrees Fahrenheit to 97.8 quickly), you can break into a sweat as your body tries to regulate your temperature. 

When there are hormone fluctuations and a few other factors, it’s even more likely that pregnant women will experience night sweats. Here’s why they happen, how to prevent them, and when they are a sign you need an evaluation with your healthcare provider. 

What causes night sweats during pregnancy?

In addition to normal nighttime thermoregulation, some pregnancy-specific issues cause night sweats, including hormones and increased blood volume. These changes are normal, so sweating more and having hot flashes during pregnancy and after birth is typical as well, says Monte Swarup, MD, an Arizona-based OB-GYN and founder of HPD Rx. Here are seven common causes.

Changing hormones

Women are susceptible to night sweats and hot flashes during hormonal fluctuations that occur during pregnancy, postpartum, and menopause. A 2013 study found that 35% of women reported night sweats during pregnancy due partly to estrogen and progesterone hormonal shifts. 

Increased blood flow

In the first trimester, your blood vessels begin to widen to allow for more blood flow: initially, this helps with the development of the placenta, and later all the extra blood plasma (almost 50% more than usual) keeps the mother’s organs well-supplied with blood as the mother’s blood supports the circulation of two humans. This vascular dilation means there’s more blood closer to the skin surface, making it easier to experience sudden flushes of heat.

Increased metabolism

Speaking of working harder, your body is also more metabolic during pregnancy, says Dr. Hoffman, and it burns calories at a higher rate, which creates more heat. Even when lying in bed trying to sleep, your body is working hard, so it’s no surprise you feel warmer at night. 

Infection or illness

If you have a fever, sweating is the body’s way of trying to prevent overheating. Since you’re unfortunately not immune to illness during pregnancy, it’s possible that your sweating is due to an illness- or infection-based fever. In fact, pregnancy is an immunocompromising condition.  This means that pregnant women are more at risk than nonpregnant women for infections during pregnancy. 

Dr. Hoffman says our own impressions of our body temperature based on how hot or cold we feel are pretty unreliable, so if you think you have a fever, take your temperature with a thermometer. Anything at or over 100.4 degrees Fahrenheit is a fever, so contact your healthcare provider to discuss any other symptoms and next steps. 

Eating carbs before bed

When you eat a high-carb meal (like those late-night pancakes you were craving), your body produces a lot of insulin, says Dr. Hoffman, which causes a quick drop in blood glucose. This can induce sweating soon after you go to bed.

Low blood sugar

Sweating because of low blood glucose can also be a sign of diabetes, so if you feel like your blood sugar is dropping overnight when you aren’t carb-loading before bed, discuss your concerns with your provider. 

But don’t worry too much about night sweats being a sign of gestational diabetes: Dr. Swarup says gestational diabetes is usually asymptomatic, so the best thing to do is be tested for it during pregnancy at the recommended time (between 24 and 28 weeks of pregnancy). Your healthcare provider may add a hemoglobin A1c test to your initial obstetrical lab work in order to diagnose pre-existing Type 2 diabetes.

RELATED: What are normal blood sugar levels? 

Thyroid problems 

Having hyperthyroidism or an overactive thyroid can cause excessive sweating as well. But Dr. Hoffman says several other clear side effects and symptoms usually occur first, like rapid breathing, increased heart rate, and diarrhea. Sweating is more of a second-tier symptom, so it likely wouldn’t be the thing to tip you off to a thyroid imbalance during pregnancy. 

When are night sweats common during pregnancy?

Night sweats can occur at any point during your pregnancy since hormones begin fluctuating and your blood volume starts to increase as soon as you become pregnant. They’re just as common in early pregnancy as in the second or third trimesters. But because your blood volume tends to peak at around 34 weeks gestation and your resting metabolic rate rises in the third trimester, you may be particularly prone to night sweats toward the end of your pregnancy.

Unfortunately, if hormone levels, blood volume, or metabolic rate are to blame for your night sweats, they probably won’t go away before the end of your pregnancy. And the unfortunate news is that you may be even more prone to night sweats in the postpartum period if you breastfeed your baby, says Dr. Hoffman, because your prolactin levels elevate and your estrogen levels drop (low estrogen is a common cause of night sweats, though experts don’t quite know why).

How to get relief

If a biological process like pregnancy hormones or increased metabolism is the cause of your night sweats, there’s not much you can do to get rid of them. But there are some ways you can help your body maintain a more consistent temperature throughout the night, as well as some lifestyle changes to make up for the things you can control. Here are 6 tips to try.

1. Stop drinking liquids before bedtime. Dr. Hoffman says constantly waking up to use the bathroom during the night can disrupt your sleep enough to cause more episodes of night sweats; by limiting fluids after 7 p.m., you should wake up less. Be sure to increase fluids in the morning to help you stay hydrated.
2. Limit carbohydrates before bedtime. Carb-heavy snacks or meals can cause sudden drops in blood glucose, which can cause sweating. If you’re hungry before bed, stick to pregnancy-safe proteins like a serving of cottage cheese or yogurt, some nuts or nut butter, or a hard-boiled egg—all of which can satisfy your hunger without spiking your blood sugar too much. 
3. Take acetaminophen and Benadryl. If your night sweats keep you up a lot at night and make it hard to sleep, Dr. Hoffman says you can take a dose of acetaminophen combined with a dose of Benadryl. Doing this will lower your body temperature as you fall asleep and help you stay asleep.  
4. Invest in cool bedding. Dr. Hoffman says moisture-wicking pajamas or cotton sheets, or bed sheets and pillows designed to provide a cooling effect, can make a big difference in your nighttime comfort level.
5. Don’t pile on the blankets. If you’re pregnant during the winter, it might be tempting to bundle up before bed, but as your body temperature rises at night, you’ll probably end up too hot. Opt for lightweight bedding and turn up the thermostat in your room just a bit more than usual in the colder months, if needed. 
6. Increase the airflow in your room. A ceiling fan or oscillating floor fan can keep cool, fresh air moving through your space during the warmer months. Installing an air conditioner, even just in your bedroom, can also help. 

When should I be concerned about pregnancy night sweats?

For the most part, having night sweats or hot flashes during pregnancy is typical and not a sign of a more serious health condition. Even when excessive sweating can be a warning sign—like in the case of thyroid problems—it’s usually precipitated by other symptoms first.

The only time night sweats indicate a problem is when they’re associated with fever due to illness or infection. Fever in pregnancy warrants a call to your healthcare provider; while you can manage most low-grade temperatures at home with acetaminophen, rest, and fluids, your healthcare provider will ask you about other symptoms that signal illness or infection, such as cough, back pain, or burning with urination, advises Dr. Hoffman.

It’s more likely, though, that your night sweats are just one more thing to endure during pregnancy and not a cause for concern. Dress yourself and your bed in light, breathable fabrics like cotton, choose your bedtime snacks and drinks wisely, and circulate the air in the bedroom to reduce night sweats—and remember what helps and what doesn’t because if you breastfeed, you might need those tips and tricks again for those postpartum night sweats.