For some cases with irregular menstrual cycles, we used letrozole and, if necessary, hMG to
stimulate monofollicular growth. The common method used was as follows: letrozole 2.5–5 mg
was administered from cycle day 3 to 7, and then follicle growth was monitored beginning on
day 10. At times treatment included a low dose of hMG (75 IU/day) to stimulate follicular and
endometrial lining growth. Administration of 10,000 IU of hCG and the timing of FET were
performed according to the above criteria.
For patients with thin endometria during either natural cycles or stimulation cycles, hormone
therapy was recommended for endometrial preparation, specifically, oral E2 (ethinylestradiol;
Shanghai Xinyi Pharma) 75 μg/day from cycle day 3 onwards. Once the endometrial lining was
>8 mm thick, Femoston (Solvay Pharmaceuticals B.V.) 8 mg/day was started. The time of
thaw/transfer was determined on the third day after Femoston administration. The maximum
number of transferred embryos was two per patient. When pregnancy was achieved, the P
supplement was continued until 8 weeks of gestation.
Statistical Analysis
The primary outcome measure was the number of oocytes retrieved. The secondary measures
included the clinical pregnancy rate, ongoing pregnancy rate, and FET implantation rate. Clinical
pregnancy was defined as the presence of a gestational sac with fetal heart activity during
ultrasound examination 7 weeks after ET. The implantation rate was defined as the number of
gestational sacs divided by the number of embryos transferred. The miscarriage rate was defined
as the proportion of patients with spontaneous termination of pregnancy.
In the table presented in this study, data are presented as the mean ± SD, and in Figure 1, the
hormone profile is presented as the mean ± SEM. Data were analyzed by the one-way analysis of
variance method, using Bonferroni and Dunnett's test where appropriate. P<.05 was considered
statistically significant. All data were analyzed using the Statistical Package for the Social
Sciences for Windows (ver. 16.0, SPSS Inc.).
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Figure 1. The flowchart of the study.
Results
Three hundred seventy-eight women were screened for the study. A total of 242 women were
selected, enrolled, and treated according to study protocol. The remaining 136 women were
rejected in accordance with predefined study exclusion criteria. All participants succeeded in
producing oocytes, with a range of 1–44. Two hundred twenty-seven women (93.8%) had
highest-quality embryos to cryopreserve, while 15 patients were excluded from the study
because they did not produce highest-quality embryos. Of the 227 women, 173 (71.5%)
completed a total of 229 FETs by the end of the research period (March 2013), including 119
women who underwent one FET, 52 women who completed two FETs, and two women who
finished three FET cycles. The remaining 54 women did not complete their FET cycles before
the end of the study (Fig. 1). Sixty-eight women completed postnatal outcome follow-up after
FET.
The mean patient age in the study was 30.8 ± 3.6 years, with minimum and maximum ages of 21
and 38 years, respectively. The mean BMI was 21.2 ± 2.9. The mean duration of patient
infertility was 4.0 ± 2.9 years. In terms of the cause of infertility, primary infertility accounted
for 48.4% of the cases (117/242) and secondary infertility accounted for 51.6% of the cases
(125/242).
The following data detail the medication administration, cycle characteristics
of ovulation induction during the luteal phase, and clinical outcomes. The mean duration of hMG
stimulation was 10.2 ± 1.6 days, with a mean dose of 2,211.3 ± 422.7 IU. The mean duration
of letrozole administration was 8.3 ± 2.1 days, with a mean dose of 21.8 ± 8.1 mg. A total of 189
women were administrated MPA, with a mean duration of 3.7 ± 3.1 days and a mean dose of
36.8 ± 31.4 mg. The mean number of antral follicles before luteal-phase ovarian stimulation was
11.4 ± 5.5. The mean number of follicles with diameters larger than 10 mm on the day of
ovulation triggering was 13.9 ± 7.8. The mean number of follicles with diameters larger than 14
mm on the day of ovulation triggering was 11.1 ± 5.5. The mean number of oocytes retrieved
was 13.1 ± 8.5, including 11.2 ± 7.2 mature oocytes. There is a positive correlation b
