Lower embryonic loss rates among twin gestations following assisted reproduction

Purpose: To determine whether maternal age and number of transferred embryos influence early pregnancy losses in twin pregnancies compared to singletons following IVF/ICSI. Methods: We compared the pregnancy loss rates in singleton (n = 549) and twin (n = 252) gestations, stratified by maternal age (≤35 and > 35 years) and the number of transferred embryos (1–3 and 4–9). Results: Loss rates of singleton pregnancies were significantly higher than that in twins (OR 3.0, 95% CI 1.9, 4.9), especially among singletons conceived after transfer of 4–9 embryos (OR 5.0, 95% CI 2.2, 11.9). Younger mothers of twins had lower loss rates (OR 0.3, 95% CI 0.1, 0.9). Conclusion: Twins have a significantly reduced spontaneous miscarriage rate compared with singletons following IVF/ICSI. Higher implantation rates per cycle (i.e., development of twins rather than one live embryo) may represent a better capacity of the uterus for early embryonic development.