ODDS OF LIVE BIRTH FOLLOWING FIRST FRESH VERSUS FROZEN EMBRYO TRANSFER IN WOMEN’S FIRST ART CYCLE USING 154,000 SARTCORS CYCLES 2014-2018

To compare live birth ART outcomes per cycle start between first fresh versus frozen embryo transfer (FET) in women’s first ART cycle. This was a retrospective cohort study for autologous first ART cycles in the SARTCORS database from 2014-2018. We compared live birth rate per cycle start for first fresh versus first FET cycles in women who had no prior history of ART. FET were only included if they were the first FET for a given retrieval and occurred within one calendar year of the initial retrieval. Cycles in which transfer type were omitted or in which race was not clearly defined were excluded. Multivariate logistic regression was used to test the association between live birth-rate outcomes versus method of transfer (fresh versus FET). We analyzed 154,054 ART cycles from the years 2014-2018. Retrieval cycles indicating a history of prior ART were excluded. A total of 102,290 fresh embryo transfers and 51,764 initial FET transfers were analyzed. Multivariate analysis noted frozen embryo transfers were associated with a higher likelihood of live birth, OR 2.0 (95% CI: 1.96-2.11, p<0.001). This reflects model adjustment accounting for age, obesity (BMI ≥ 30), parity, race/ethnicity, number of embryos transferred, etiology of infertility or AMH level (log-transformed). When stratified according to age group, the odds of live birth were greater for FET among all age categories with the odds of live birth incrementally increasing up to age 42 and then decreasing for those older than 42 (Table 1).Tabled 1Table 1:Age (yrs)NOdds Ratio (95% CI; P value)<3559,6671.6 (1.5 – 1.7, P<0.001)35-3732,5271.9 (1.7 – 2.0, P<0.001)38-4029,6612.6 (2.4 – 2.8, P <0.001)41-4215,3183.1 (2.7 – 3.6, P <0.001)>4216,8812.0 (1.8 – 2.2, P<0.001)Table: Odds Ratios of the association between Transfer Type (fresh versus FET) on live-birth Outcome in five age-groups. OR > 1 implies a greater likelihood of live-birth outcome via FET. Open table in a new tab These data suggest that the probability of live birth is significantly higher for the first FET following a retrieval compared to a first fresh embryo transfer. The increased likelihood of live birth outcomes for FET versus fresh transfer appears to increase with age in patients younger than 42 years.