Expected numbers of embryos to transfer in in vitro fertilization: what affects?

Introduction: Increased multiple pregnancy rate and resultant complications are some of the greatest concerns for in vitro fertilization (IVF) due to the practice of multiple embryo transfer. Although in some countries elective single embryo transfer has already been mandatory, in majority of other countries, clinical counsel still plays very important role to affect expected number of embryos transferred (ENET). Here we aim to explore the impact factors for ENET of IVF patients in order to provide scientific suggestions for clinical counsel before ET. Methods: We performed a survey of impact factors on ENET using a self-designed questionnaire in a total of 1154 IVF couples. Questions about policy change, medical concerns, and social-cultural information were included. Results: When the policy for restriction of family size was lifted, the percentages for double embryos transferred (77.8% vs. 63.7%) and multiple embryos transferred (8.0% vs. 3.9%) decreased significantly, while more tended to choose single embryo transfer (SET) (14.2% vs. 32.4%, P<0.01). Patients of more advanced age weremore likely to choose SET (12.9% for 18–24 y, 11.8% for 25–29 y, 12.0% for 30–34 y, 22.4% for 35–39 y, and 28.6% for over 40 y, P=0.01). More subjects with previous labor preferred SET than those without (23.3% vs. 12.4%, P<0.01). In addition, the proportion of SET choice was significantly decreased with infertility duration prolonged (1 vs. 2 y vs. 3 vs. ≥ 4 y: 24.2% vs. 14.9% vs. 11.1% vs. 11.2%, P< 0.01). On the basis of further investigation for reasons of ENET, specific formula including individual weighted policy, medical, and social-cultural factors was derived. Conclusions: Collectively, ENET for IVF patients is a complex, multi-factorial decision. The heterogeneity between patients due to differential policy restriction, medical concerns, and social-cultural background should be fully considered in clinical counsel about ENET.