Table 1.
The characteristics of 1210 patients included the sex ratio among singleton births following the first single blastocyst frozen embryo transfer (FET) cycles performed from January 2015 to February 2019
| Characteristic | Description |
|---|---|
| Number of cycles | 1210 |
| Mean maternal age (years±SD) | 30.5 ± 4.5 |
| Mean paternal age (years±SD) | 31.6 ± 5.4 |
| Mean maternal BMI (kg/m2) | 23.6 ± 3.2 |
| Mean duration of infertility (years±SD) | 3.3 ± 2.6 |
| Type of infertility (%) | |
| Primary | 541 (44.7%) |
| Secondary | 669 (55.3%) |
| Main infertility cause (%) | |
| Female factor | 661 (54.6%) |
| Male factor | 307 (25.4%) |
| Mixed factor | 193 (16%) |
| Unexplained infertility* | 49 (4%) |
| Type of fertilization (%) | |
| IVF | 855 (70.7%) |
| ICSI | 355 (29.3%) |
| Day of embryo transfer (%) | |
| D5 | 783 (64.7%) |
| D6 | 427 (35.3%) |
| Blastocyst quality of transfer (%) | |
| Good | 638 (52.7%) |
| Poor | 572 (47.3%) |
| Singleton livebirths (%) | |
| Male | 667 (55.1%) |
| Female | 543 (44.9%) |
Note: Data are presented as the mean ± SD and proportion (%). BMI = body mass index; D = day; IVF = in vitro fertilization; ICSI = intracytoplasmic sperm injection; *Unexplained infertility is rarely used as a diagnostic indicator for IVF in China because it is a controversial diagnosis