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How Much Weight Should You Gain When You’re Pregnant?

It’s not a secret that we’ve got a messed up relationship with bodies and weight gain in our culture.  With the complicated self-esteem and health issues that come with people focusing on weight as a virtue in health and beauty, this issue even bleeds into how we think about pregnancy — a time when a pregnant person should be able to focus wholly on growing a healthy, happy human inside of them. Plus, postpartum, there’s an unspoken expectation for women to “bounce back” post-pregnancy, it can add unnecessary pressure. It should go without saying, but gaining weight during pregnancy is a necessity, and definitely is a good thing — and everyone else’s opinions about your body (save for your own and your doctor’s) are irrelevant.

“Physiologically, women gain weight with maternal water and body fat and also to accommodate all of the factors and processes of pregnancy,” says Heather Anaya, DO, maternal fetal medicine physician at Northwestern Medicine.

Of course, gaining the right amount of weight for your body is crucial, since it can help protect your health and the health of your baby. “It is normal and healthy to gain weight during pregnancy not only because of the weight of the growing baby, but also because your body fluid doubles to support the extra blood flow of pregnancy,” says Lori Hardy, MD, obstetrician and gynecologist at Northwestern Medicine. “There is also weight that goes to the breasts, placenta, uterus, increased blood volume, and amniotic fluid.”

Throughout your pregnancy, the goal is to keep weight gain as steady as possible because your baby requires a daily supply of nutrients that comes from what you eat, explains Dr. Hardy. “It is normal for your weight to fluctuate a little from week to week — most women will gain the majority of their pregnancy weight in the latter half of the pregnancy,” she says.

When it comes to how much is healthy to gain during your pregnancy, it depends on your pre-pregnancy body weight. “According to the American College of OB/GYN as well as the Institute of Medicine (IOM), pregnancy weight gain should be based on your pre-pregnancy BMI, which is calculated by taking weight in kilograms divided by height in meters squared,” says Dr. Hardy. “There are tables online to help you calculate this or you can ask your doctor. As with everything in medicine, there will be a range of what is healthy, not just one specific number.”

If you don’t gain enough weight during your pregnancy, you’re putting your baby at risk for serious health issues, including you’re more likely to have a premature baby or a baby with low birth weight. “Babies born with low birthweight may be more likely than babies born at a normal weight to have certain health conditions later in life, including diabetes, heart disease, obesity and metabolic syndrome,” says Dr. Hardy.

But on the flip side, there definitely is such a thing as gaining too much weight during pregnancy. “This can put the mother at risk of pregnancy complications like gestational diabetes and preeclampsia, along with increased risk of a ‘large for gestational age’ infant or a too-big baby, which increases the risk of birth trauma, including lacerations, excess bleeding, and shoulder dystocia, as well as increased risk of cesarean delivery,” says Dr. Hardy. Gaining too much weight during pregnancy also increases the chances of difficulty losing weight after the pregnancy.

When it comes to healthy weight during and after pregnancy, doctors have a few tips:

Continue working out

“Exercise is important for mental and physical well-being, but the point should not be to exercise away extra calories,” says Dr. Anaya. Keeping active during your pregnancy shouldn’t be too different from pre-pregnancy.“Most healthy pregnant women can continue their pre-pregnancy workouts but some modifications may be necessary as the pregnancy progresses,” says Dr. Hardy. “But, check with your doctor if you have questions about how much or how intensely you can exercise if you have any pregnancy complications.” Working out regularly during your pregnancy will help reduce your risk of diabetes and reduce insulin resistance. If you’ve had gestational diabetes in previous pregnancies, it’s especially important to incorporate regular physical activity during your pregnancy.

Watch your calorie intake during your pregnancy 

During pregnancy, you’re not technically “eating for two.” “You don’t need to increase caloric intake until your second trimester,” says Dr. Hardy. “And, even then, you only need about 300 extra calories per day.” This can equate to two cups of low-fat milk, an apple and two tablespoons of peanut butter, or whole wheat pita and a one-quarter cup of hummus. If you have a history of diabetes, you may want to talk to your doctor about a low-carb diet as well, says Dr. Anaya.

Post-pregnancy, breast feeding mommas need extra calories

“Extra calories are quoted in the range of up to 500 extra per day during lactation (primarily breast feeding or pumping), which requires an extraordinary amount of energy from the mom,” says Dr. Anaya. “Lactation helps with postpartum weight loss but should not be the sole strategy.”

Don’t rush to get back to your pre-pregnancy weight

“It’s hard to be patient, but be gentle with yourself about your weight loss goals after pregnancy,” says Dr. Hardy. “Your body goes through many changes during pregnancy that take time to reverse — it may take up to a year. You can begin exercising at six weeks postpartum with a goal of losing one or two pounds each week.”

A version of this story was published May 2019.

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