Second trimester amniocentesis in assisted conception versus spontaneously conceived twins

Objective To compare the outcome of amniocentesis in twins conceived with assisted reproduction technology (ART) versus spontaneously conceived twins. Design Retrospective analysis of case records between 1993 and 2006. Setting University-affiliated tertiary center for fetal medicine. Patient(s) 167 ART twin pregnancies and 275 spontaneous twin pregnancies. Intervention(s) Genetic amniocentesis. Main Outcome Measure(s) Comparison of pregnancy loss rate and perinatal outcome between the ART and spontaneous twin-pregnancy groups. Result(s) The fetal loss rate was similar between the two groups (4.2% vs. 4.0% in the ART twins and spontaneous twins, respectively), although the interval between amniocentesis to miscarriage was statistically significantly shorter in the ART twins than the spontaneous twins (6.2 and 20.1 days, respectively). In all cases, fetal loss refers to the loss of the entire pregnancy. The preterm delivery rate before 37 weeks was statistically significantly higher in the ART group (64.1%) compared with controls (49.5%). Conclusion(s) Amniocentesis in ART twins carries a fetal loss rate similar to spontaneous twins. However, ART twins have a statistically significantly increased risk of preterm delivery especially before 32 weeks' gestation.