RENO, NEV. — Obstetricians are delivering more sets of twins early—a trend that is improving neonatal mortality, Cande V. Ananth, Ph.D., said at the annual meeting of the Society for Maternal-Fetal Medicine.
Black twins, however, are not benefiting equally by this more aggressive practice. According to federal statistics, 44% of white and 53% of black twin births occurred before 37 weeks' gestation in 1989. In 2000, those percentages rose to 57% for whites and 61% for blacks.
These increases largely reflected obstetricians' decisions to deliver twin infants early—but more so among whites, said Dr. Ananth of the department of obstetrics and gynecology at the University of Medicine and Dentistry of New Jersey, New Brunswick.
Medically indicated preterm delivery among white twins rose 51% for the 11-year period, and 33% among black twins.
Among the whites, this medically indicated early delivery significantly affected perinatal mortality, defined as stillbirth after 22 weeks' gestation or neonatal mortality within 28 days of birth.
Perinatal mortality decreased by 41% during the period overall. It fell by 31% among the medically indicated deliveries, and, because of the large increase in medically indicated preterm births among whites, that 37% reduction accounted for 10% of the overall decline.
Among the black twins, perinatal mortality declined 37% overall and 34% among medically indicated preterm births. However, largely because the increase in medically indicated preterm deliveries was less in blacks, that decline accounted for only 5% of the overall drop.
A reduction in mortality tied to births following premature rupture of membranes was more important among blacks.
The study also found that preterm birth following spontaneous onset of labor rose 3% among white twins and fell 1% among black twins. Preterm birth following premature rupture of membranes fell 3% among whites and 7% among blacks.