Candidate for the Lee B. Lusted Student Prize Competition
Purpose: Fresh embryo transfer (ET) is currently the norm for in vitro fertilization (IVF). A growing body of literature, however, suggests that pregnancies resulting from frozen-thawed ET have better obstetric and perinatal outcomes than pregnancies resulting from fresh ET. Better outcomes may be related to improved endometrial receptivity and placentation in the more physiologic hormonal environment associated with frozen ET. We used decision analysis to assess the effect of performing elective frozen ET for all IVF cycles.
Methods: A decision-analytic model was developed to compare complication rates for fresh and frozen ET in hypothetical cohorts of women of differing ages (<35, 35-37, 38-40, 41-42, and 43-44). Live-birth rates were derived from 2010 U.S. CDC data. Rates of preterm birth, preeclampsia, and small for gestational age infants based on maternal age and type of IVF cycle were derived from the literature. One-way and multi-way sensitivity analyses were performed to test the robustness of our findings.
Results: For women under 35, fresh and frozen ET result in a similar number of uncomplicated live births. For women aged 35-37, 38-40, 41-42, and 43-44, frozen ET was associated with a higher rate of uncomplicated live births (table). These results were sensitive to the protective effect of frozen ET on the likelihood of complications as well as live-birth rate per cycle with fresh and frozen ET. If the total live-birth rate with fresh ET was more than 3% (35-37), 2.6% (38-40), 1.6% (41-42), or 0.7% (43-44) higher than the total live-birth rate with frozen ET, fresh ET became the preferred strategy for maximizing likelihood of an uncomplicated live birth.
Conclusions: Frozen-thawed embryo transfer optimizes the uncomplicated live-birth rate in women over 35 undergoing IVF. These results are sensitive to the relative likelihood of live birth with fresh versus frozen ET and the protective effect of frozen ET on perinatal complications. Along with individual embryo quality, this data should be considered when contemplating the optimal IVF strategy for women 35 and older. In women under 35, the higher live-birth rate of fresh ET should be weighed against the higher risk of perinatal complications. Additional prospective research is needed to assess live-birth and complication rates following elective frozen-thawed embryo transfer.
