The Dangers of Excessive Weight Gain During Pregnancy

Learn why gaining too much weight while you're pregnant could be risky for you and your baby.

pregnant woman weight
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If you're pulling the "eating for two" card, you might need to find another excuse to devour that donut. A study in Obstetrics and Gynecology found that nearly half of all women gain too much weight during pregnancy, which can lead to health issues for both mother and baby.

"When a woman gains too much weight during pregnancy, it increases the risk of her baby being born too large, which can contribute to subsequent obesity in the child as well as delivery complications such as vaginal tears, excess bleeding, and an increased need for a Caesarean section," explains study co-author Andrea Sharma, Ph.D., an epidemiologist at the Center for Disease Control's Maternal and Infant Health Branch. "Also, it can be harder for the mother to lose excess weight gained during pregnancy which can put her at a greater risk for obesity."

For the study, researchers from the Centers for Disease Control and Prevention analyzed data representative of all women who gave birth to a full-term baby in 2010 or 2011 in 28 states. They found that 47% of women gained too much weight during pregnancy.

Also, women who were overweight or obese before conception were nearly three times more likely to gain more weight than the recommendations as compared with those women who started pregnancy at a normal weight (though women with the highest BMIs were also almost twice as likely to gain too little weight.)

Anita Sadaty, M.D., an Ob-Gyn based in Great Neck, New York, says that you don't need to gain a ton of weight to have a healthy baby. According to the Institute of Medicine, women who are underweight to begin with (BMI less than 18.5) should gain 28 to 40 pounds during pregnancy; those who start at a normal weight (BMI between 18.5-24.9) should gain 25 to 35 pounds; those who are overweight (BMI 25-29.9) should gain 15 to 25 pounds; and those who are obese (BMI 30 or greater) should gain 11 to 20 pounds. While a few pounds above the threshold is probably fine, too much can have negative consequences.

"Pregnancy certainly does not equate to 'eating for two'; in fact, the extra caloric requirements are actually relatively small," says Sharma. "In general, a woman doesn't need any additional calories during the first trimester. During the second trimester, she only needs an additional 340 calories, and she only needs an extra 450 calories during the third trimester. To give you an idea, an additional 350 calories is approximately equal to adding a snack consisting of one medium apple, one cup of non-fat Greek yogurt and a handful of almonds."

Another factor leading to being overweight during pregnancy: Many pregnant women don't exercise as much as they should.

"We come from a culture where exercise during pregnancy hasn't been encouraged, but we have to change that," says Sharma. "Women with uncomplicated pregnancies should get at least 150 minutes per week of moderate-intensity aerobic activity during pregnancy. They can work to achieve this goal by taking brisk 10 to 20 minute walks throughout the week."

Here's a look at the risks of gaining too much weight during pregnancy. Keep these in mind when you're mid-craving, and it might be a little easier to put down those Oreos.

​​​​​​​You’ll experience more pregnancy symptoms.

Not every woman will experience the most annoying pregnancy symptoms, including varicose veins, achy joints, and heartburn. But those who tack on too much weight are more likely to develop them, Dr. Sadaty says. Extra weight puts pressure on your body overall, making it harder for blood and fluids to move around on the inside, and for you to move around on the outside. This can trigger leg cramps, hemorrhoids, backaches, physical exhaustion, and more.

You're more likely to develop diabetes.

"Women who gain too much weight during pregnancy are more prone to gestational diabetes, a dangerous condition in which your body is unable to produce enough insulin to balance glucose levels in your blood," says Kathleen M. Rasmussen, Sc.D., R.D., professor of nutritional sciences at Cornell University and chair of the committee on the report Weight Gain During Pregnancy: Reexamining the Guidelines at the Institute of Medicine.

The good news is that most moms with gestational diabetes won't remain diabetic after the baby is born. Still, being diagnosed with the condition puts you at higher risk for getting it again during a future pregnancy and for developing type 2 diabetes later in life.

You're more likely to have complications during your delivery.

Gaining too much weight typically increases the size of your baby. Having a big baby isn't necessarily a bad thing, but it can make labor more difficult. Large babies have a tough time getting pushed out naturally, often making a last-minute caesarean section necessary.

"And heavier babies tend to get shoulder dystocia, a condition in which the shoulders are larger than the head, making natural birth extremely painful and, in many cases, impossible," Rasmussen says. Having a C-section isn't the end of the world – after all, some women plan for them – but it can delay milk production and lengthen your post-birth recovery time.

The more you gain, the longer it takes to lose it.

"Bouncing back after giving birth is a lot easier when don't gain too much weight," Dr. Sadaty says. Once that baby's out, you'll notice an immediate drop in weight – about 11 pounds, which accounts for your new little one, the amniotic fluid, and the no-longer-essential placenta. The rest of the weight can take months to lose – longer if you gain a significant amount.

"Even if you breastfeed you're going to have to put in a lot of effort to work off all those extra pounds," says Andrea Orbeck, a fitness trainer in Los Angeles who helps A-list clients maintain a healthy weight during pregnancy.

You put your baby at a disadvantage, too.

"An overweight mother is more likely to give birth to a large baby with a greater risk of diabetes and obesity throughout childhood, and beyond," Rasmussen says.

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