Modifiable risk factors for growth restriction in twin pregnancies

Objective: This study was undertaken to evaluate modifiable risk factors for adverse fetal growth in twin pregnancies. Study design: A large cohort study from a database of women with twin gestations identified at risk for preterm labor was performed. Examining each infant's birth weight and gestational age at delivery, infants were classified as being average (AGA), large (LGA), or small (SGA) for gestational age, using the Alexander reference curve. Clinical and demographic factors were compared between patients delivering at least 1 SGA infant and AGA pairs using Pearson's χ²Student t test statistics and logistic regression. Results: There were 11,827 twin pregnancies evaluated. Risk factors associated with SGA deliveries included tobacco abuse, poor weight gain, lean prepregnancy body mass index, African American race, and nonmarried. The logistic regression identified tobacco abuse as the single greatest risk for poor fetal growth, (odds ratio [OR] 1.95; 95% CI [1.68, 2.27]). Weight gain of less than one-half lb/wk also increased SGA risk (OR 1.35; 95% CI [1.16, 1.68]), whereas weight gain greater than 1 lb/wk decreased SGA risk (OR 0.77; 95% CI [0.68, 0.86]). Conclusion: Tobacco abuse and weight gain are the modifiable risk factors, which require intervention during a twin pregnancy. Patients should be encouraged to stop tobacco abuse and gain a minimum of one-half lb/wk in the later half of pregnancy to minimize the risk for growth restriction.