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
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
- 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
- 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