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It’s one of the most common pregnancy myths: When you’re expecting, you’re “eating for two.”

In reality, the average pregnant woman needs to eat just a few hundred calories more per day, which is the equivalent of two or three small snacks. Eating more than that can lead to too much weight gain, which can cause pregnancy complications for both mom and baby.

As your pregnancy progresses, it’s essential to provide your body with the proper nourishment. The key is making sure that you’re getting enough nutrients to help your baby grow while avoiding excessive weight gain.

Studies have found that only about one-third of women gain the right amount of weight during pregnancy ­­— and about half gain too much. Putting on too much weight is common for women of all sizes, but it’s especially prevalent among women who begin their pregnancies overweight or obese.

How much weight should you gain during pregnancy?

The answer depends on your body mass index (BMI) before pregnancy. BMI is a measurement of body fat based on height and weight. To calculate yours, divide your body weight in kilograms by your height in meters squared, or simply use the Center for Disease Control’s BMI calculator.

Here are the Institute of Medicine’s guidelines for weight gain during pregnancy:

Your BMI Before Pregnancy

Recommended Weight Gain for One Baby

Recommended Weight Gain for Twins

Less than 18.5 (underweight) 28-40 pounds 50-62 pounds
18.5-24.9 (normal weight) 25-35 pounds 37-54 pounds
25.0-29.9 (overweight) 15-25 pounds 31-50 pounds
30.0+ (obese) 11-20 pounds 25-42 pounds

If you’re carrying triplets or more, talk to your healthcare provider about how much weight you should gain.

What are the risks of gaining too much weight?

Lack of physical activity, excessive food intake, or certain health conditions can all contribute to someone gaining too much weight during pregnancy.

Putting on more weight than recommended is associated with gestational diabetes (a type of diabetes that occurs only in pregnancy), especially in the first trimester. This condition increases your risk of:

  • Having a baby who’s too large, which may lead to complications during delivery or Cesarean delivery (C-section)
  • Low blood sugar, which can cause lightheadedness, shaking, and sweating — or seizures, confusion, or lost consciousness if left untreated
  • Developing type 2 diabetes later in life
  • Preeclampsia (high blood pressure during pregnancy)

In your baby, gestational diabetes may cause:

  • Premature birth (born before 37 weeks)
  • Breathing problems
  • Diabetes or obesity later in life

Even if you don’t develop gestational diabetes, gaining too much weight can lead to plenty of complications, such as having a premature birth or a C-section. It can also cause leg pain, back pain, and varicose veins. Additionally, it may be more difficult to lose the extra weight after pregnancy; this can lead to health conditions like high blood pressure and diabetes.

What are the risks of gaining too little?

Gaining less weight than recommended comes with its own set of risks. There are several reasons someone may not gain enough weight during pregnancy, including:

  • Morning sickness (severe nausea and vomiting during pregnancy, a condition called hyperemesis gravidarum, is associated with weight loss)
  • Loss of appetite
  • Low pre-pregnancy weight
  • Fast metabolism
  • Other medical reasons

If your weight gain is outside the guidelines on the low end, your baby could be small for their gestational age or be born prematurely. Babies who are born small may have breastfeeding troubles, miss developmental milestones, and have an increased risk for illness.

Where does the weight go?

It’s not just the baby (weighing an estimated 7.5 to 8 pounds) that leads to higher numbers on the scale. By the end of your pregnancy, you can expect an extra:

  • 2-3 pounds for the placenta, the temporary organ that delivers oxygen and nutrients to your baby
  • 2-3 pounds of breast tissue
  • 4 pounds of blood
  • 2-3 pounds of amniotic fluid, the fluid that surrounds and protects your growing baby
  • 5-9 pounds for stored fat for delivery and breastfeeding
  • 2-5 pounds for your uterus

Throughout your pregnancy, though, this varies. For example, blood volume and amniotic fluid rises sharply in the second trimester and tapers off in the third trimester (more on that below).

Slow and Steady? Sort of.

Most women can plan on gaining between half a pound and one pound per week throughout their pregnancy. But while you should notice a general upward trend, don’t expect it to be a consistent rate from week to week. You’ll likely experience slow weight gain in the beginning and in the end of your pregnancy, with something of a surge during the second trimester.

First trimester: Your baby is quite tiny, so there’s no need to consume extra calories during this time. (If you’re among the 70 to 80 percent of pregnant women who struggle with morning sickness, you may find that eating more — or eating much at all — is out of the question anyway.) During those first 12 weeks, you may gain a few pounds, or none at all. If you find that you’ve gained more than several pounds, take extra care in tracking your weight in the second and third trimesters so that you can adjust your caloric intake and physical activity as necessary.

Second trimester: As your baby starts to get bigger — their weight will multiply more than seven times this trimester — you should be putting on more pounds, too. If you were a healthy weight before your pregnancy, you’ll need an additional 340 calories per day. That’s equivalent to a half a sandwich and a glass of skim milk. In this trimester, you may find that you experience more rapid weight gain. That’s because most of the weight you gain is water, and water weight can come on very fast. Expect to add about 12 to 14 pounds during these three months.

Third trimester: Both you and your baby will continue to put on the pounds, but your weight gain will begin to slow. You may even find that you lose a little weight, which may be due to decreasing levels of amniotic fluid, the inability to eat large meals, and other factors. If you were a healthy weight before your pregnancy, you’ll need an additional 450 calories per day, which is equivalent to a serving of low-fat yogurt, a four-ounce serving of chicken breast, and a whole-grain roll.

One important note: A sudden increase in weight could be a sign of preeclampsia. This serious condition, which can lead to fetal growth restriction, placental abruption, or preterm labor, causes a sharp increase in bodily fluid. Make sure to attend your prenatal visits so you can be checked for preeclampsia. And if your scale shows an unexplained increase in three to five pounds over the course of a week, talk to your provider.

Gaining the Right Amount of Weight: 5 Tips

#1 Track your weight. Download a weight tracker app like Ovia Pregnancy Tracker (iOS; Android) or simply use an old-fashioned notebook to check your numbers against the recommended guidelines. When you weigh yourself:

  • Take off your shoes first
  • Wearing lightweight clothing
  • Use the same scale on the same day and time each week, if possible

Just remember that your weight gain likely won’t be at a steady rate.

#2 Communicate with your provider. If you’re concerned about gaining too much (or too little) weight during pregnancy, talk with your doctor. They can help you come up a nutrition and exercise plan or refer you to someone else who can, like a registered dietitian who specializes in pregnancy.

#3 Stay active. After getting clearance from your doctor, aim to get about two and a half hours of moderate-intensity aerobic activity per week. The key is to find low-impact ways to get your cardio in. Good options include:

  • Walking
  • Swimming
  • Low-impact aerobics
  • Cycling on a stationary bike
  • Strength training with light weights

As a bonus, exercise can help improve your mood, increase your energy, and ease pregnancy symptoms like constipation and swelling.

#4 Stock up on smart food options. MyPlate, a food-planning tool from the U.S. Department of Agriculture, offers personalized plans based on your height, pre-pregnancy weight, and activity level. Good foods for pregnancy include fresh fruit, wild salmon, oats, and avocado. Remember to avoid foods that may not be safe for pregnant women.

#5 Don’t try to lose weight during pregnancy. Restricting your food intake is potentially harmful for you and your baby. If you’re worried about the weight you’ve been gaining during pregnancy, don’t cut back on calories; instead, talk to your provider. And if possible, lose weight before getting pregnant so that you start off at a healthy BMI.

A Closing Thought

Don’t stress about losing the weight you’ve gained during pregnancy. You may be seeing numbers on the scale that you’ve never seen before, and that can be daunting. But don’t fret. By continuing to make smart food choices and staying physically active (hello, stroller walks!), you’ll gradually be able to fit into those pre-baby jeans again.

Are you pregnant or planning to become pregnant soon?

At WakeMed Obstetrics & Gynecology, we provide a full range of services for women of all ages in Raleigh, Cary, Clayton, Holly Springs, North Raleigh, Brier Creek and Morrisville, North Carolina.












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Elizabeth Jarvis MD