The appropriate amount of weight to gain during pregnancy is based on multiple factors, including the mother's initial weight, trimester of pregnancy and number of fetuses. The Institutes of Medicine has updated their recommendations for pregnancy weight gain.
Mother's Pre-Pregnancy Weight Consideration
In general, the recommendation for pregnancy weight gain is 25 to 35 pounds. A woman who is considered to be underweight should gain more--about 28 to 40 pounds. Women who are overweight or obese, with a BMI greater than 25, should gain less weight--between 10 to 25 pounds over the course of the nine months.
Trimester Weight Gain
During the first trimester of pregnancy, a woman's weight gain is minimal, consisting of only about two to four additional pounds. During the second and third trimesters, weight gain increases more rapidly, to about one pound a week.
Weight Gain Recommendation for Multiples
Women who are at a normal weight prior to pregnancy and who are carrying twins should gain between 37 and 54 pounds over the course of their pregnancy, according to the March of Dimes. Women with triplets should gain between 45 and 60 pounds. Women carrying more than three fetuses should add an additional ten pounds per baby. In multiple pregnancies, weight gain is most rapid during the second trimester, with many babies delivered prior to 38 weeks of gestation.
Where Does the Weight Come From?
Of the total amount of weight gained during pregnancy, the baby likely only contributes about seven to eight pounds. The remainder of the weight comes from the placenta and amniotic fluid, increase in breast and uterine tissue, increase in fat stores and an expansion of the blood supply.
The Dangers of Excess Weight Gain
According to the Institutes of Medicine, mothers-to-be who gain excess weight during pregnancy face an increased risk for cesarean section due to babies of larger birth weight. They also may be at increased risk of retaining the weight after the pregnancy ends. Babies who are above normal birth weight risk premature birth, stunted growth and blood sugar issues.
Weight Loss During Pregnancy
Health experts agree that attempting to achieve weight loss during pregnancy is dangerous for the baby's health and growth. Should a woman begin to gain too much weight, it is recommended to reduce caloric intake or increase exercise to maintain current weight status rather than trying to achieve a reduction in weight.
