Outcomes of singleton births after blastocyst versus nonblastocyst transfer in assisted reproductive technology

Objective: To compare obstetric and perinatal outcomes of singleton births after assisted reproductive technology (ART) with blastocyst transfer (days 5 to 6) versus nonblastocyst transfer (days 2 to 4). Design: Retrospective cohort study. Setting: Monash IVF. Patient(s): 4,202 women who conceived using in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) between 2004 and 2009. Intervention(s): Records analysis of fresh and frozen-thawed embryo transfers resulting in singleton births of at least 20 weeks' gestation. Main Outcome Measure(s): Perinatal outcomes: preterm birth, low birthweight, very low birthweight, small for gestational age, large for gestational age, preeclampsia, antepartum hemorrhage, placental abruption, placenta previa, and postpartum hemorrhage; and covariates: maternal age, year of birth of the baby, private health insurance status, maternal body mass index, smoking status, parity, gender of baby, and variations in treatment procedures. Result(s): Multivariate analysis found no statistically significant difference between transfers on days 5 and 6 and days 2 and 4 for all maternal and perinatal outcomes. There were modest increases in the adjusted odds ratios for preeclampsia (adjusted odds ratio 1.72, 99% confidence interval 0.93-3.20) and placenta previa (1.65, 0.92-2.98). Conclusion(s): Obstetric and perinatal outcomes after blastocyst transfer on days 5 to 6 are similar when compared with embryo cleavage-stage transfers on days 2 to 4. (Fertil Steril (R) 2012;97:579-84. (C) 2012 by American Society for Reproductive Medicine.)