Women with twin pregnancies who have inadequate gestational weight gain during the second trimester have a more than twofold increase in the risk of preterm birth before 32 weeks, compared with those with adequate weight gain, findings from a retrospective cohort study suggest.
Inadequate weight gain between 20 and 28 weeks’ of gestation was the strongest predictor of preterm birth before 32 weeks in the study of 489 women with twin pregnancies, according to Dr. Kate E. Pettit, who will report the findings on Monday at the annual meeting of the American Congress of Obstetricians and Gynecologists in Chicago.
The rate of preterm birth prior to 32 weeks was 37.6% among women with inadequate weight gain during weeks 20-28, compared with 15.2% among those with adequate weight gain during that time period. Inadequate weight gain prior to 20 weeks was not associated with preterm birth, said Dr. Pettit of the University of California, San Diego, and her associates.
Other factors found to be associated with preterm birth in this study were monochorionicity and short cervical length, she noted.
All viable twin pregnancies delivered in the UCSD Health System between 2001 and 2013 were included in the study. Adequacy of weight gain was determined by dividing the minimum Institute of Medicine weight gain recommendation by 37 weeks.
"This study affirms the association between poor total gestational weight gain and preterm birth, and highlights the likely crucial period of time of 20-28 weeks of gestation that may be a target for future intervention trials," Dr. Pettit said in an interview.
The higher rate of preterm birth prior to 32 weeks’ of gestation among those with inadequate weight gain was attributable to spontaneous preterm birth, as there was no difference in the rates of indicated preterm birth among those with and without adequate weight gain, she explained, noting that "the biologic plausibility of the effect of gestational weight gain on the rate of spontaneous preterm birth is unknown."
"However, there is much room for improvement in gestational weight gain counseling, and a need for additional interventional trials to determine if adequacy of gestational weight gain at 20-28 weeks’ will, in fact, be one of the modifiable factors in the quest to reduce preterm birth in twin pregnancies," she said in an interview.
Interventions could include early goal-setting, nutritional assessment, and activity modification, she added.
Dr. Pettit reported having no disclosures.