Why You Feel Warmer when Expecting

Hot pregnant

An increase in basal or resting body temperature may be one of the first hints that you are expecting, even before you miss that first period.

Every woman has a different basal temperature, usually 97 to 99 degrees, but internal temperatures tend to rise after ovulation. Hormonal fluctuations can cause woman’s baseline temperature to rise by as little as 0.4 to 0.8 degrees Fahrenheit. If no conception takes place, a woman’s temperature will return to normal after her period, but if she becomes pregnant that slightly higher baseline temperature will be the norm until she gives birth. That first uptick in the internal thermostat is just the start of it.

As the body’s hormone levels adjust to perform their vital role in protecting and nurturing a baby, women often experience a range of first and second trimester symptoms ranging from nausea to weepiness to feeling uncomfortably hot. A 2010 study found that hot flashes and night sweats were commonly reported during the first and second trimester of pregnancy.

As the pregnancy progresses, there are more reasons to feel warmer than usual. An obvious reason is the weight gain. Carrying around an extra 25 to 35 pounds provides an insulating layer that is likely to warm you up and slow down your circulation.

Next, there’s an increase in blood volume. During pregnancy, a woman’s body can increase her plasma volume by more than 40 percent. Why should that make a woman feel warmer? To compensate for the added volume, blood vessels dilate slightly, causing warm blood to flow to the skin’s surface. In women carrying twins, triplets or quadruplets, blood volume can rise proportionately.

As the baby grows he or she also radiates heat so it’s not surprising that expectant moms feel anywhere from pleasantly toasty to unpleasantly sweaty.

If you are feeling uncomfortable, it’s important to discuss this—and any other symptoms—with your healthcare provider. But there’s no need for concern. In general, feeling hotter than normal is nothing to worry about.

You should, however, remember to drink plenty of water. While pregnant it is extra important to avoid dehydration during hot weather or while exercising. Learning the signs of dehydration—feeling lightheaded, unusually tired or having urine that is scant and dark—is a smart idea but it’s even smarter to consciously avoid dehydration in the first place.

To minimize your chance of dehydration, drink plenty of water, more than you might if you were not pregnant, especially if you are exercising. The Institute of Medicine recommends at least 10 glasses of fluid a day, and that total does not include caffeinated drinks since caffeine is a diuretic. Drinking water before and after you exercise is a good rule.

There are a few simple ways to feel more comfortable in your warmer skin. First, give some thought to what clothes make you most comfortable. Wear light breathable fabrics. Dressing lightly in layers means you can remove layers should you suddenly feel hot. Carry a small personal fan and a spray bottle of water for a quick cool off. A cold compress on your forehead can help. Go swimming if you can. Eat cool refreshing foods such as fruit.

Once your baby is born, your body’s ability to regulate internal heat will return to normal, usually within a week or two of delivery.

Joan MacDonald
Joan Vos MacDonald has written about health and fitness for newspapers, magazines and websites. She is a member of the National Association of Science Writers and the author of two books on health-related topics, "Tobacco and Nicotine Dangers," for young adults, and "High Fit Home," a design book about fitness and architecture. She lives in upstate New York near her children and grandchildren.

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