Twin pregnancy: Very low or very high weight gains associated with adverse outcomes

There is an old adage for pregnant women "eat for two." Considering this, it should be "eat for three" for women with twin pregnancy?? According to a recent study, this seems to be bad advice. The study, published in the Obstetrics & Gynecology journal has found that both very low or very high weight gain is not good for women with twin pregnancies and is associated with adverse outcomes.

"Both very high and very low weight gain was associated with more preterm births and infant death," wrote the authors. "Targeted modifications of weight gain during pregnancy in women carrying twins might improve pregnancy outcomes."

There isn’t a lot of evidence for an ideal amount of weight gain in a twin pregnancy. Lisa M. Bodnar, the University of Pittsburgh in Pennsylvania, and colleagues evaluated the association between gestational weight gain in twin pregnancies and pregnancy outcomes including small-for-gestational-age (SGA) and large-for-gestational-age (LGA) birth, preterm birth before 32 weeks of gestation, cesarean delivery, and infant death within each prepregnancy body mass index (BMI) category.

Researchers used data from Pennsylvania-linked infant birth and death records (2003–2013). They studied d 54,836 twins born alive before 39 weeks of gestation. Total pregnancy weight gain (kg) was converted to gestational age-standardized z scores.

From that data, the team calculated an increased risk of poor birth outcomes when weight gain was:

• Less than 31 pounds or greater than 60 pounds in underweight and normal-weight women;


• Less than 24 pounds or greater than 62 pounds in overweight women;


• Less than 14 pounds or greater than 57 pounds in obese women.

Key findings include:

• Gestational weight gain z score was negatively associated with SGA and positively associated with LGA and cesarean delivery in all BMI groups.


• The relation between weight gain and preterm birth was U-shaped in nonobese women.


• An increased risk of infant death was observed for very low weight gain among normal-weight women and for high weight gain among women without obesity.


• Most excess risks of these outcomes were observed at weight gains at 37 weeks of gestation that are equivalent to less than 14 kg or more than 27 kg in underweight or normal-weight women, less than 11 kg or more than 28 kg in overweight women, and less than 6.4 kg or more than 26 kg in women with obesity. The bias analysis supported the validity of the conventional analysis.

The National Academy of Medicine recommends that women who are normal-weight or underweight gain 17-25 kilograms (37-55 pounds) during a twin pregnancy, and that overweight women gain no more than 11-19 kg (24-42 lbs).

"Very low or very high weight gains were associated with the adverse outcomes we studied. If the associations we observed are even partially reflective of causality, targeted modification of pregnancy weight gain in women carrying twins might improve pregnancy outcomes," concluded the authors.