Pregnancy Weight Gain Guidelines Explained

From the WebMD Archives

Every woman who is expecting a child ponders pregnancy weight gain. Some take pregnancy as license to eat as much as they want. Others regard pregnancy pounds with disdain and worry that putting on weight during those nine months will forever ruin their figure.

Whatever your opinion about pregnancy weight gain, it pays to know how much is right for you. Recently released recommendations by an expert panel of the Institute of Medicine (IOM) and the National Research Council -- the first guidelines of their kind in nearly 20 years -- explain how many pounds to put on and how pregnancy weight gain affects your health and your child's health.

But numbers are one thing; putting it into practice is another thing altogether. Here are some common questions women have about their pregnancy weight gain.

How Much Weight Should I Gain During Pregnancy?

The amount of weight you should gain during pregnancy is based on your prepregnancy body mass index (BMI) and how many children you're carrying. BMI estimates body fat based on height and weight. You can calculate your BMI on the WebMD BMI Plus Calculator.

Once you know your BMI, you've got a starting point for pregnancy weight gain. Women with higher BMIs are advised to gain less; those with lower BMIs should put on more pounds with pregnancy.

Here is a summary of weight gain guidelines for a single baby based on your BMI:

  • If your BMI is less than 18.5: Gain 28 to 40 pounds
  • If your BMI is 18.5 to 24.9: Gain 25 to 35 pounds
  • If your BMI is 25 to 29.9: Gain 15 to 25 pounds
  • If your BMI is 30 or greater: Gain 11-20 pounds

Here is a summary of weight gain guidelines for twins:

  • If your BMI is less than 18.5: Ask your doctor
  • If your BMI is 18.5 to 24.9: Gain 37 to 54 pounds
  • If your BMI is 25 to 29.9: Gain 31 to 50 pounds
  • If your BMI is 30 or greater: Gain 25 to 42 pounds

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When Should I Start Gaining Weight During Pregnancy?

When it comes to pregnancy pounds, timing matters.

Chances are, weight gain during the first three months will be minimal -- and should be, according to the IOM guidelines.

You don't need any extra calories during the first trimester; although the baby's growth is rapid, he is so small that his development doesn't warrant additional energy. However, you may add some pounds to your frame during the first three months because you're hungrier or because of fluid retention. Some women even lose weight because they don't feel well enough to eat their usual diet.

Once the second trimester starts, and the baby's growth begins in earnest, gaining weight on a steady basis is a must. Plan on putting on about a pound each week with a prepregnancy BMI of 24.9 and below, and about a half pound a week if you had a prepregnancy BMI of 24.9 and above.

What Happens If I Gain Too Much or Too Little During Pregnancy?

In the short term, gaining the suggested amount of weight reduces the risk of preterm birth (birth before 37 weeks of gestation) and promotes a baby that isn't too big or too small at delivery.

In the long run, research suggests that the greater the weight gain during pregnancy, the higher the risk of having an overweight child and one with higher blood pressure. Children who are born too small, which can result from inadequate weight gain during pregnancy, are more prone to certain chronic conditions, including heart disease and diabetes, during adulthood.

What if you miss the mark for recommended weight gain? If you're off by just a few pounds either way, it probably won't make much of a difference. The IOM guidelines provide a range in each BMI category, suggesting that good outcomes are achieved with all different weight gains. Listen to the advice of your doctor or nurse-midwife about weight gain, but if you have doubts, ask what's right for you.

How Much Extra Food Should I Eat While Pregnant?

Pregnancy hormones can play havoc with appetite, causing some women to feel famished. Others are daunted by nausea, vomiting, and fatigue that diminish their desire for food. In both cases, the best strategy is trying as much as possible to adhere to a balanced diet that accounts for physical activity and stage of pregnancy, like the ones offered at MyPyramid.gov.

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A nutritious pregnancy eating plan with adequate calories -- about 340 more calories each day than your prepregnancy needs, starting in the second trimester, and about 450 more than your prepregnancy diet during the last three months of pregnancy -- should be enough to prevent constant hunger. Women who are particularly physically active during pregnancy may need more calories, however.

A woman pregnant with twins should eat about 440 more calories each day starting in the second trimester, and 500-600 more calories more per day in the last trimester.

Choosing foods that fill you up as part of a balanced pregnancy diet improves eating satisfaction. For example, whole grains, vegetables, and legumes are filled with fiber to keep you fuller for longer, without any extra calories. Drink plenty of fluids; it works with fiber to keep you full and to prevent constipation, a common pregnancy complaint.

Why Does Pregnancy Weight Gain Vary So Much From Woman to Woman or From Pregnancy to Pregnancy?

It's difficult to understand why some women gain more than the recommended amounts during one pregnancy when they seem to be monitoring every bite, then put on the same amount of weight with the next baby when they pay much less attention to how much they eat. Unless you monitor every morsel you eat and every move you make, it's impossible to chalk up the pregnancy weight gain to anything but pregnancy metabolism.

Women who have struggled with eating disorders may be fearful of gaining weight, even during pregnancy. It's important to discuss your feelings about food with a qualified health care professional. Intentionally restricting calories to keep weight gain low can harm your baby's growth and development. Pregnancy is no time to diet, even if you started off overweight.

How can I control my cravings?

Avoid using your pregnancy as a reason to overeat or to choose low-nutrient, high-fat foods over more nutritious fare.

Giving in too often to pregnancy cravings for high-fat, calorie-laden foods, such as bacon double cheeseburgers and brownie sundaes, can lead to unnecessary weight gain.

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And it may program your child to prefer unhealthier food choices. A 2007 study in the British Journal of Nutrition suggests that women who regularly feast on so-called junk food during pregnancy may have children with a propensity for becoming overweight later in life because they prefer the taste of foods rich in sugar, fat, and calories.

A salt-laden diet won't pack on fat, but may cause you to retain fluid, which will show up on the scale as extra weight. Excess fluid may cause discomfort and aggravate high blood pressure.

To control cravings for any food, prevent yourself from getting too hungry. Eat meals and snacks on a regular basis during the day and be sure to combine a source of protein, such as hard-cooked eggs and low-fat yogurt, with complex carbohydrates, including whole-grain breads and cereals. That's not to say your diet must be treat-free. Even the healthiest pregnancy eating plan can include moderate portions of the foods you crave, but not every day.

Why is it important to have a healthy weight before I get pregnant?

According to the IOM, the ideal situation is conceiving at a healthy weight, and gaining the right number of pounds for the subsequent nine months. Starting pregnancy at a healthy weight provides a baby with better odds of developing normally and minimizes complications, including high blood pressure and cesarean delivery, in mom.

Once you're pregnant, the horse is out of the barn, as far as your body weight goes. However, it's never too early to plan for the next pregnancy. There's no need to rush, but make an effort to return to your prepregnancy weight, or a healthy weight, within a year of delivering your baby.

WebMD Expert Column Reviewed by Kecia Gaither, MD, MPH on July 20, 2014

Sources

SOURCES:

Institute of Medicine: "Weight Gain During Pregnancy: Reexamining the Guidelines."

Mamun, A. Circulation, 2009; vol 119: pp 1720-1727.

Oken, E. American Journal of Obstetrics and Gynecology, 2007: vol 196: p 322 e1-8.

Barker, D. Journal of the American College of Nutrition, 2004; vol 23: pp 588S-95.

Bayol, S. British Journal of Nutrition, 2007; vol 98: pp 843-85.

NutritionMD: "Pregnancy and Nutrition."

Massachusetts General Hospital: "How Much Weight Should I Gain?"

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