Why You Could Be Having Pregnancy Night Sweats — and What to Do About Them

In scientific literature, night sweats can be defined as drenching sweats during sleep that require you to change clothes. But they can also refer to the less drastic nighttime hot flashes that leave you feeling stifled.

In general, night sweats are fairly common. We don’t have data on the prevalence of night sweats in pregnant women specifically, but a 2013 study of women revealed that 35 percent reported having hot flashes while pregnant. But why?

Night sweats and temperature regulation issues can be caused by a number of conditions and circumstances, including a thyroid disorder, infections, and yes — normal physiological changes that come with pregnancy. Let’s boil it down.

Changes in hormones

It’s true: These important (but sometimes eye roll inducing) regulators can push your body into the hot zone. It may stem from estrogen and progesterone transitions during pregnancy that catapult from a carousel ride to a thrilling roller coaster seemingly overnight.

This 2016 study on sex hormones’ effects on thermoregulation explains that estrogens lower body temperatures by boosting the body’s ability to dissipate heat. But how? Sweat! In addition, progesterone may be at play raising the body’s temps.

So all of this night sweat business could be a result of your body simply trying to adjust to a sudden or drastic hormonal or metabolic change.

Increased blood flow

A pregnant woman’s blood plasma volume increases by up to 40 percent compared to pre-pregnancy. And it continues to rise to 60 percent (or more) by the end of the third trimester.

Your blood vessels then dilate (widen) to deliver more blood to your skin’s surface. And voila! There’s your sensation of always feeling “warmer.”

There’s evidence to suggest your temperature control is further complicated while sleeping. During a natural human circadian rhythm, core body temperatures steadily decrease throughout sleep cycles, but guess what regulates this process? Your skin’s outer temperature, which a 2012 study states can adjust blood flow to the skin to help regulate core body temperature.

It’s plausible that the natural rise in peripheral skin temperature during pregnancy could interfere with the body’s normal mechanism for decreasing core body temperatures in sleep. This might even cause that sudden wake-up due to feeling drenched.

Thyroid issues

Just when you thought you’d heard enough about hormones, we’re here to tell you more — this time, thanks to your thyroid gland.

Thyroid hormones help regulate metabolism and body temperature. Too much thyroid hormone may have you feeling overheated in general or during sleep.

This 2016 review of physiological changes during pregnancy explains that during the first trimester, thyroid hormones thyroxine (T4) and tri-iodothyronine (T3) increase, falling again slightly as you enter the second and third trimesters.

TSH (thyroid stimulating hormone), on the other hand, decreases in the beginning of the first trimester and increases again before the second trimester begins.

Pregnancy may also cause an iodine deficiency, which can alter your thyroid hormone function even further.

These normal thyroid hormone fluctuations during pregnancy, in addition to those that may be caused by more serious thyroid disorders and diseases, can cause temperature regulation issues and, therefore, lead to night sweats.

If you have chronic night sweats that aren’t going away or a history of thyroid issues, we urge you to speak to your OB-GYN for further evaluation.

Infections

Night sweats could be a signal of a more serious infection or condition. It’s a classic symptom of tuberculosis and lymphoma, which would be an extremely rare reason for night sweats during pregnancy.

But pregnancy can increase a woman’s risk of certain infections that may cause night sweats due to normal changes in the immune system, among other physiological adjustments.

An article published in 2014 explains that pregnant women can be more susceptible to — and more severely affected by — certain organisms. Some of these include:

• influenza virus (flu)
• hepatitis E virus
• herpes simplex virus
• malaria parasites

During pregnancy, there’s also a heightened susceptibility to foodborne infections caused by the bacteria Listeria monocytogenes.

If your night sweats are accompanied by other concerning symptoms — such as muscle aches, fever, flu-like symptoms, nausea, and diarrhea — it’s critical to call your OB immediately.

Medication side effects

From antidepressants to over-the-counter cold, acid reflux, and decongestant medications, many drugs carry the side effect of excessive sweating or night sweats. If you’re taking any medication or supplement while pregnant, check with your pharmacist or OB about your night sweat risk.

One medication to be aware of is ondansetron (Zofran), which is commonly prescribed during pregnancy to help relieve nausea. If you’re taking Zofran and experience persistent night sweats, consult with your OB.

Low blood sugar

During pregnancy, your metabolism is in overdrive to give your little one all the nutrition required to grow from the size of a mere seed to a watermelon. That means that you can be left a little depleted if you don’t consume enough calories, or equally balanced calories, throughout the day.

If this is the case, you could experience hypoglycemia, or low blood sugar. And night sweats, or nocturnal hypoglycemia, can be a tell-tale sign.

While this study states that hypoglycemia is rare in pregnant women who are not diabetic, women who have any form of diabetes or its risk factors should be aware of the possible connection to night sweats.

Could they be an early sign of pregnancy?

In the wee stages of pregnancy, you might have heard the rumor that night sweats or hot flashes could be a sign that you’ve got a bun in the oven.

It’s true that your basal body temperature increases during specific times of your menstrual cycle. This spike usually happens when your body is signaling your ovaries to release an egg, which is considered your fertile window — the time period during which you could conceive.

It’s also entirely possible that hormone fluctuations in early pregnancy could cause you to wake up hot or down right soaked, but it’s always advised to lean on your trusted pregnancy test and OB to be, well, “positive.”

First trimester to postpartum

A 2010 longitudinal study indicated that a pregnant woman’s core body temperature registers highest during the first trimester, and then decreases throughout each trimester and up to 3 months postpartum.

One 2013 study, however, found that 29 percent of women reported hot flashes after delivery. All this is to say that the ups and downs of pregnancy and delivery can also bring unexpected ups and downs with your temperature.

And if you’re waking up soaked during the “honeymoon” phase of pregnancy, it will likely end soon, along with those nagging first trimester fatigues.

We know those prego mama worries can jump to worst-case scenario in seconds. But the answer to keeping cool is often a simple fix.

Managing night sweats starts with figuring out what’s causing them. For most pregnant women, the occasional night sweat is considered a normal result of the body’s transitions throughout this exciting time.

However, that doesn’t mean you can’t find relief. Talk to your doctor about any new symptom you have, including night sweats, to determine the possible cause and remedies.

In the meantime, consider modifying your sleep environment. Studies show that your room temperature and even pajama choices could influence your body’s ability to cool itself while getting your Zzz’s.

Turn down your AC a few degrees, use lighter-weight bedding, and select soft cotton or more breathable fabric for your nightwear.

If you suspect a more serious medical condition or medication is causing your night sweats, or if your nights sweats occur with a fever, rash, or other concerning symptom, it is especially important to contact your OB-GYN immediately.

In most cases, a night sweat here or there is considered routine during pregnancy — but we know it doesn’t feel normal. Take a deep breath. Grab your ice pack. And will your way through this wild (and sometimes sweaty) ride to motherhood.

If you have chronic night sweats or night sweats accompanied by other serious symptoms, call your OB for help.