Pregnancy Weight Gain Calculator

Recommended weight gain during pregnancy

Gaining weight is a normal and necessary part of pregnancy. Only part of the gain is the baby; the rest supports the pregnancy and prepares the body for breastfeeding. How much is right depends mostly on your body mass index (BMI) before you became pregnant. In 2009 the Institute of Medicine (IOM, now the National Academy of Medicine) published ranges that are still used by the American College of Obstetricians and Gynecologists (ACOG) and the CDC.

Women who start pregnancy underweight are advised to gain the most, and women with obesity the least, because stored energy reserves differ. The table shows the recommended total gain for each BMI group, along with the provisional ranges for twin pregnancies. There was not enough evidence to set a twin range for women who are underweight.

The pattern of gain matters as well as the total. Most women gain only about 1 to 4.5 pounds (0.5 to 2 kg) in the first trimester, when nausea is common and the baby is still tiny. From the second trimester on, the recommended rate is roughly 1 pound a week for underweight and normal-weight women, about 0.6 pounds a week for overweight women and about 0.5 pounds a week for women with obesity. The calculator spreads the remaining gain evenly from week 14 to week 40 so that the schedule lands on the IOM total.

For a typical full-term pregnancy with a 7.5-pound baby, the extra weight is distributed roughly as follows:

• Baby: about 7 to 8 pounds
• Larger breasts: 1 to 3 pounds
• Larger uterus: about 2 pounds
• Placenta: about 1.5 pounds
• Amniotic fluid: about 2 pounds
• Increased blood volume: 3 to 4 pounds
• Increased fluid in tissues: 2 to 3 pounds
• Fat stores for birth and breastfeeding: 6 to 8 pounds

Potential complications of suboptimal weight gain

Gaining too little is linked to a higher chance of a baby who is small for gestational age and of preterm birth. Gaining too much is linked to gestational diabetes, high blood pressure disorders, a large baby, cesarean delivery and weight that remains after the baby is born, which can raise risks in a later pregnancy. Most women do not land exactly within the range, and being outside it is a reason to talk with your provider rather than a cause for alarm. Dieting to lose weight during pregnancy is not recommended.

What to eat during pregnancy?

Energy needs rise less than many people expect. In the first trimester most women need no extra calories. In the second trimester the increase is about 340 calories a day and in the third about 450, roughly a glass of milk and a sandwich. Twin pregnancies and very active women may need more. The goal is to make the extra food count, choosing nutrient-dense options instead of simply eating more.

A balanced plate during pregnancy looks much like a healthy plate at any other time: half vegetables and fruit, a quarter whole grains and a quarter protein foods such as beans, lentils, eggs, poultry, lean meat, tofu or fish, along with dairy or fortified alternatives. Whole grains and legumes supply fiber, which helps with the constipation common in pregnancy.

Several nutrients deserve particular attention. Folic acid helps prevent neural tube defects, so all women who could become pregnant are advised to take 400 micrograms daily, ideally starting at least a month before conception. Iron needs rise to 27 milligrams a day to support the larger blood volume; lean red meat, poultry, beans and fortified cereals help, and pairing them with vitamin C improves absorption. Calcium and vitamin D build the baby's bones, and iodine and choline support brain development. A prenatal vitamin covers many of these gaps, but it complements food rather than replacing it.

Fish is a valuable source of omega-3 fats such as DHA. The FDA and EPA advise pregnant women to eat 8 to 12 ounces a week of fish that is low in mercury, such as salmon, sardines, trout, cod, shrimp and canned light tuna, and to avoid high-mercury species such as shark, swordfish, king mackerel, tilefish from the Gulf of Mexico, bigeye tuna and marlin.

Some foods carry a risk of infection that is more dangerous in pregnancy. Avoid unpasteurized milk and cheeses, raw or undercooked meat, poultry, eggs and seafood, refrigerated smoked seafood, deli meats and hot dogs unless heated until steaming, and raw sprouts. Wash fruits and vegetables well. These steps reduce the risk of listeria, salmonella and toxoplasmosis.

Limit caffeine to less than 200 milligrams a day, about one 12-ounce cup of coffee. No amount of alcohol is known to be safe during pregnancy, so the safest choice is not to drink. Drink plenty of water; needs increase to roughly 10 cups of fluid a day.

Staying active helps keep weight gain on track. Unless your provider advises otherwise, aim for about 150 minutes a week of moderate activity such as brisk walking, swimming or prenatal exercise classes. If nausea, food aversions, a history of disordered eating or a condition such as gestational diabetes makes eating well difficult, ask your provider for a referral to a registered dietitian.

Frequently asked questions

Sources

• CDC – Weight Gain During Pregnancy
• ACOG – Weight Gain During Pregnancy
• National Academies – Weight Gain During Pregnancy (2009)
• FDA – Advice about Eating Fish