The effect of ICSI, maternal age, and embryonic stage on early clinical loss rate of twin versus singleton pregnancies

Objectives: To compare early loss rates between twin and singleton pregnancies following ART. Study design: First-trimester sonography counted the number of embryos with positive heartbeat in women undergoing IVF/ICSI and transfer of one to three embryos. The number of lost pregnancies was calculated from a second-trimester sonogram. Loss rates of the entire pregnancy were related to maternal age < 38 or > 38 years, IVF or ICSI, and cleavage or blastocyst stage embryo transfers (in ICSI cases). Results: Patients underwent IVF with (n = 672) and without (n = 189) ICSI. The overall odds of miscarrying the entire singleton pregnancy were 2.6 times that of a twin gestation (95% Cl 1.5, 4.5). The disadvantage for singletons compared to twins seems more apparent in pregnancy after ICSI in the subgroup of patients < 38 years (OR 2.9, 95% CI 1.5, 5.8). In this subgroup, the disadvantage conferred to singletons appeared only among days 2-3 embryo transfers (OR 3.0, 95% CI 1.3, 7.2). Conclusion: A significantly lower early spontaneous loss rate of twin pregnancies seems related to ICSI followed by cleavage stage embryo transfer in patients < 38 years. (c) 2006 Elsevier Ireland Ltd. All rights reserved.