Maternal and perinatal outcomes and factors associated with twin pregnancies among preterm births: Evidence from the Brazilian Multicenter Study on Preterm Birth (EMIP)

Objective To compare maternal and perinatal outcomes between twin and single preterm births (PTB) and associated factors. Methods A cross-sectional multicenter study was conducted in Brazil with 4046 PTBs from April 2011 to July 2012. Causes of PTB, use of tocolytics, corticosteroids, and antibiotics in twin and single pregnancies, and factors possibly associated with twinning were evaluated using χ2 tests. Maternal and perinatal outcomes were assessed with prevalence ratios (PR). Results The main cause of PTB in twin pregnancy was spontaneous onset of preterm labor. Tocolytics were more frequently used in twins (26.9% vs 20.2%). Factors associated with PTB in twins were: maternal age >25 years (62.3% vs 53.4%); interpregnancy interval >3 years (39.0% vs 33.4%); no history of PTB (87.4% vs 79.6%); no previous maternal conditions (78.0% vs 73.3%); no alcohol abuse (88.5% vs 84.3%); no drug addiction (97.5% vs 94.5%); and >6 prenatal visits (46.5% vs 37.6%). Twin pregnancies run a 46% higher risk of cesarean delivery, while first and second twins face a 20% higher risk of low birth weight. Twin pregnancies run increased risks for admission to the NICU, cerebral hemorrhage, necrotizing enterocolitis, and any adverse perinatal outcome. Conclusion Preterm twin birth is associated with low birth weight and worse neonatal outcomes.