Frozen embryo cycles
Of all allocated patients, the total number of initiated FET cycles with
thawed embryos was 665 in the PPOS group and 259 in the long agonist
group. In the PPOS group, 662/665 (99.5%) had one frozen embryo
transfer compared to 257/259 (99.2%) in the long agonist group. In the
majority of FET cycles Day-3 embryos were thawed and transferred.
Presence of top quality of embryos after thawing and endometrial
thickness were similar between the two groups. More women had double
embryo transfer in the frozen embryo cycles in the agonist group
(75.5%) than in the PPOS group (50.8%). Hormonal cycles used for
endometrium preparation were used in more FET cycles in the PPOS group
482/662 (72.8%) compared to 104/257 (40.5%) in the long agonist group
(P < 0.001) (Table III).
Women in the PPOS group were less
likely to have a live birth following their first FET cycle
139/433 (32.1%) compared to those
in the long agonist group 85/192
(44.3%) (OR: 1.721; 95% CI: 0.588–0.884; P = 0.003). However, this
difference disappeared after inclusion of additional FET cycles. Of all
FET cycles, a total of 206/662 (31.1%) cycles resulted in a live birth
in the PPOS group versus 110/257 (42.8%) in the long agonist group (OR:
0.727; 95% CI: 0.607–0.871; P <0.001) .The implantation rate
of total FET cycles was also lower in the PPOS group compared with that
in the agonist group 293/1004
(29.2%) and 157/455 (34.5%)
(OR: 0.846; 95% CI: 0.721–0.992; P
= 0.041) (Table IV).
In regression analyses with embryo transfer day and endometrium
preparation as the independent variables, we found no impact on the
total LBRs from FET for embryo transfer day (OR = 0.87; 95% CI
0.35–1.67; P = 0.51). But for endometrium preparation, we found a
significant effect (OR = 0.59; 95% CI: 0.25–0.96; P = 0.03) (data not
shown in table). Hormonal FET cycles were correlated with lower total
FET LBRs.