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Nutrition and Weight Gain During Pregnancy

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You will need twice as much iron in your second and third trimesters as you did before pregnancy. This extra iron supports the extra blood in your system and helps with the growth of the placenta and the fetus. Your iron requirements are slight during the first trimester of pregnancy, and taking iron supplements in the first trimester may aggravate morning sickness.

After the first trimester, take a daily supplement containing 30 mg of iron (most prenatal vitamins include iron). A woman with a multiple pregnancy is advised to take 60 mg to 100 mg of iron daily.3 Iron supplements can cause an upset stomach and constipation. Taking your iron at bedtime may decrease the chance of stomach upset. Your body absorbs iron best in small amounts when you eat it with vitamin C, so you may want to take your iron throughout the day.


Calcium is needed for the development of the fetus's skeleton. You can get enough calcium in your diet by eating or drinking 4 servings from the dairy (milk) group each day. Good sources of calcium from nonmilk sources include:

  • Greens (such as mustard and turnip greens), bok choy, kale, and watercress.
  • Broccoli and cauliflower.
  • Tofu that is "calcium-set."
  • Corn tortillas made with lime.
  • Calcium-fortified orange juice.

Weight gain during pregnancy

The recommended weight gain for a woman of normal weight is 25 lb (11.3 kg) to 35 lb (15.9 kg). You can expect to gain more if you are carrying twins.

If you are overweight, your ideal goal is less than the average weight gain, 15 lb (6.8 kg) to 25 lb (11.3 kg). If you are underweight, it is best to gain 28 lb (12.7 kg) to 40 lb (18.1 kg).

For obese women, the Institute of Medicine recommends weight gain of between 11 lb (5 kg) and 20 lb (9 kg).5 Your doctor will work with you to set a weight goal that's right for you. For more information, see the topic Obesity and Pregnancy.

Ideally, you will gain weight slowly over the entire pregnancy:

  • Up to 4 lb (1.8 kg) during the first trimester
  • 1 lb (0.5 kg) a week during the second and third trimesters

If you stop gaining weight for more than 2 weeks, or if you gain weight faster than these recommendations, consult your doctor.

Women who are pregnant with twins can expect to gain more weight.

For women at a healthy weight who are pregnant with twins, the recommended weight gain is 40 lb (18.1 kg) to 45 lb (20.4 kg).1

If you are overweight and pregnant with twins, your ideal goal is less than the average weight gain, 38 lb (17.2 kg) to47 lb (21.3 kg). If you are underweight, it is best to gain 50 lb (22.7 kg) to 62 lb (28.1 kg).1


WebMD Medical Reference from Healthwise

Last Updated: February 14, 2013
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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