PRETERM DELIVERY AFTER SELECTIVE TERMINATION IN TWIN PREGNANCIES

Objective: To determine the effect of selective termination of an abno rmal twin on the rate of preterm delivery. Methods: The study group co nsisted of 69 patients with twin pregnancies who underwent selective t ermination between 1987-1994. The comparison groups consisted of singl eton (n = 42,362) and twin pregnancies (n = 825) delivered at our inst itution during the same period. The data were analyzed by chi(2) and F isher exact test, as appropriate. P < .05 was considered significant. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calcu lated by multiple logistic regression. Results: Terminating the presen ting twin was associated with a significantly higher risk of delivery before 37 weeks (adjusted OR 4.1, 95% CI 1.4-12.3) and low birth weigh t (adjusted OR 3.8, 95% CI 1.3-11.4) compared with terminating the non presenting twin. When the termination was performed at or after 20 wee ks' gestation, only the risk of preterm premature rupture of the membr anes or preterm labor was significantly increased (adjusted OR 3.7, 95 % CI 1.2-11.5). Selective termination patients had a lower rate of pre term delivery than twin pregnancies (40 versus 58%, P < .005) but high er than singleton pregnancies (40 versus 10%, P < .001). Conclusion: S elective termination of the presenting twin at 20 weeks or later was a ssociated with a worse perinatal outcome than terminating the nonprese nting twin or performing the procedure before 20 weeks.