Effects of serum estrogen levels before frozen-thawed blastocyst transfer on pregnancy outcomes in hormone replacement cycles.

We investigated the effects of serum estrogen levels before frozen-thawed blastocyst transfer on pregnancy outcomes in hormone replacement cycles. Clinical data of 708 hormone replacement cycles with frozen-thawed blastocyst were retrospectively analyzed. According to quartile (P25) of serum estrogen levels on the endometrium transformation day, the 708 cycles were divided into group A1 (E2 < 157.5 pg/ml), group A2 (157.5 pg/ml ≤ E2 < 206.4 pg/ml), group A3 (206.4 pg/ml ≤ E2 < 302.3 pg/ml) and group A4 (E2 ≥ 302.3 pg/ml). According to quartile (P25) of serum estrogen levels on the frozen-thawed blastocyst transfer day, the 708 cycles were divided into group B1 (E2 < 147 pg/ml), group B2 (147 pg/ml ≤ E2 < 200.4 pg/ml), group B3 (200.4 pg/ml ≤ E2 < 323 pg/ml) and group B4 (E2 ≥ 323 pg/ml). According to different clinical outcomes, the 708 cycles were divided into clinical pregnant group and non-clinical pregnant group. The group A4 (E2 ≥ 302.3 pg/ml on the endometrium transformation day) was significantly lower than other groups in blastocyst implantation rate and multiple-pregnancy rate (P < 0.05). The days of taking progynova was significantly different among groups on both endometrium transformation day and frozen-thawed blastocyst transfer day (P  0.05). The mean age was significantly younger and the number of high-quality blastocysts transferred was significantly higher in the clinical pregnant group than in the non-clinical pregnant group (P  0.05). Multivariate regression analysis indicated that age was an independent factor affecting clinical pregnancy (P  0.05). The days of taking progynova and serum estrogen levels before frozen-thawed blastocyst transfer do not affect pregnancy outcomes in hormone replacement cycles.