Pregnancy rates after communal growth of preimplantation human embryos in vitro

To evaluate the effect of communal growth of preimplantation human embryos on pregnancy rates in IVF-ET. Prospective randomized study. In Vitro Fertilization Unit, Bikur Cholim Hospital, Jerusalem, Israel. Ninety-one women undergoing 91 cycles of IVF-ET. In 42 cycles (control) embryos were grown singly, in 49 cycles (study) embryos were grown in groups until transfer. Proportion of women achieving pregnancy in study and control groups. Communal growth of embryos resulted in significantly improved pregnancy rates. Intrauterine transfer of embryos grown in groups produced 43% pregnancy rates per transfer, whereas, with embryos grown individually, 24% pregnancy rates were obtained (odds ratio = 2.4). Our study suggests that, in IVF, the potential of preimplantation human embryos to produce pregnancy tends to increase when embryos are grown in groups.