Single or Double Embryo Transfer for Infertility: An Evaluation of Registry Data From Over 22 000 Treatment Cycles

Single embryo transfer (SET) is considered the most effective method for reducing multiple pregnancies in assisted reproduction. Nevertheless, couples in Germany often opt for double embryo transfer (DET) in the hope of achieving a higher success rate. The aim of this study was to evaluate the effectiveness of two consecutive SETs compared to one DET.

We conducted a retrospective analysis of data from 133 German fertility clinics. Treatment cycles between January 2017 and December 2022 were analyzed. The parameters examined were the clinical pregnancy rate (CPR) and the live birth rate (LBR), the type of birth (single or multiple), the number of children born, the percentage of premature births, and birth weight.

The rates of clinical pregnancy and live birth after fresh transfer were higher after DET than after SET (49.2% vs. 45.1% and 38.4% vs. 35.2%, respectively), but more women achieved a live birth with two SETs than with one DET (5111 of 11 205 [45.6%] vs. 4304 of 11 205 [38.4%] after DET). The number of children born per 1000 women was higher after DET (503) than after two cycles of SET (464), but DET resulted in significantly more multiple births (30.3% vs. 1.7%), fewer singleton births (26.8% vs. 37.4%), more premature births (46.5% vs. 18.1%), lower birth weight (2924.8 ± 756.8 g vs. 3264.4 ± 487.0), and significantly more very premature births.

Two consecutive SETs lower the risks associated with DET with a comparable success rate in terms of the number of babies born.