Term pregnancy and live birth subsequent to immediate uterine transfer of sperm microinjected oocyte in a natural cycle

It has been reported that it is possible to achieve a pregnancy after immediate uterine transfer of oocyte and sperm, before fertilization and cleavage were known to have occurred; there is an enormous amount of work about the optimal timing of embryo transfer, with no conclusive evidence of a gold standard satisfying patient age, endometrial receptivity, hormonal levels and embryological parameters. We hereby report a case of one 35-year-old nulligravid woman with longstanding tubal factor infertility and 3 previous failed ICSI cycles, treated with ICSI and immediate transfer of the oocyte microinjected with a spermatozoon in a natural cycle. A single oocyte was retrieved, injected with a spermatozoon and transferred 40 min after injection, resulting in an uneventful pregnancy and delivery of a healthy female infant weighing 3320 g at 40 weeks' estimated gestational age. This case, certainly novel, should be interpreted with caution. Whether confirmed for efficacy and safeness in appropriate controlled clinical trials, our present observation could offer a simple, practical and cost-effective approach in ART programs in selected patients.