In May 2009, the Institute of Medicine (IOM) of the National Academy of Science issued updated guidelines for weight gain during singleton and some twin pregnancies based on maternal weight prior to conception. The IOM declined to issue a recommendation for triplet and other multiple pregnancies, citing lack of evidence, since few such pregnancies progress to term. Ultimately, fetal growth ultrasounds provide the best method of assessing maternal nutritional intake during multiple pregnancies.
Preconceptual Body Mass Index
The IOM stratifies goals for weight gain during all pregnancies, including multiple pregnancies, based on a woman's preconceptual body mass index, known as BMI. According to the IOM, BMI less than 19.8 signals underweight, 19.8 to 25.9 is considered normal, 26.0 to 29.0 is considered overweight and greater than 29 corresponds with obesity.
Twin Pregnancy
During twin pregnancy, the IOM recommends that women of normal weight gain 37 to 54 pounds, overweight women gain 31 to 50 pounds and obese women gain 25 to 42 pounds. The IOM does not offer guidance for underweight women pregnant with twins, due to insufficient data.
Triplet Pregnancy
In the 2006 edition of "Nutrition for Pregnancy and Lactation," nutritionist Carol M. Bareuther offers recommendations for underweight, normal weight and overweight women expecting triplets, quadruplets and quintuplets. During a triplets pregnancy, Bareuther suggests a planned weight gain of 50 to 60 pounds for underweight women, 45 to 55 pounds for normal weight women and 35 to 45 pounds for overweight women.
Quadruplet Pregnancy
During a quadruplet pregnancy, Bareuther recommends planned weight gain of 60 to 70 pounds for underweight women, 55 to 65 pounds for normal weight women and 45 to 55 pounds for overweight women.
Quintuplet Pregnancy
During quintuplet pregnancy, Bareuther recommends a planned weight gain of 70 to 80 pounds for underweight women, 65 to 75 pounds for normal weight women and 55 to 65 pounds for overweight women.
Daily Calorie Intake
The Institute of Medicine does not recommend increasing calorie intake during the first trimester. During the second trimester, women expecting twins should consume about 500 additional calories each day, followed by an additional 700 calories each day during the third trimester. An additional 200 calories each day per fetus is a good starting point for triplet and other multiple pregnancies.
Fetal Growth Ultrasounds
During multiple pregnancies, obstetricians aggressively monitor fetal growth using ultrasound techniques. These fetal growth ultrasounds are more sensitive and specific than maternal weight gain for assessing the adequacy of maternal nutritional intake for pregnancies with more than one fetus.
References
- Institute of Medicine: Weight Gain During Pregnancy: Reexamining the Guidelines
- "Nutrition for Pregnancy and Lactation"; C.M. Bareuther; 2006
- "Seminars in Perinatology"; Nutrition and Multiple Gestation; B. Luke; Oct. 2005
