Table 4.
Univariate analysis of impact factors on gestational age (n = 2010).
| Exposure | Values |
Change in gestational age (weeks) |
|
|---|---|---|---|
| mean ± SD/n (%) | β (95% CI) | P-value | |
| Maternal age (year) | 30.92 ± 3.99 | −0.03 (−0.04, −0.01) | 0.0085* |
| Paternal age (year) | 32.45 ± 4.77 | −0.02 (−0.03, −0.00) | 0.0323* |
| Maternal BMI (kg/m2) | 22.30 ± 3.15 | −0.03 (−0.05, −0.00) | 0.0240* |
| Basal FSH (IU/l) | 7.64 ± 2.45 | 0.01 (−0.02, 0.04) | 0.6667 |
| AMH (ng/ml) | 2.85 ± 2.24 | 0.03 (−0.00, 0.06) | 0.0768 |
| Type of infertility | |||
| Primary | 1019 (50.70%) | Ref | |
| Secondary | 991 (49.30%) | 0.14 (−0.13, 0.41) | 0.3113 |
| Infertility duration (year) | 3.69 ± 2.71 | −0.04 (−0.09, 0.01) | 0.1149 |
| Infertility cause | |||
| Female | 1304 (64.88%) | Ref | |
| Male | 397 (19.75%) | −0.15 (−0.51, 0.21) | 0.4146 |
| Mixed | 189 (9.40%) | 0.23 (−0.30, 0.76) | 0.3891 |
| Unexplained | 120 (5.97%) | −0.25 (−0.78, 0.29) | 0.3663 |
| Prior gonadotropin cycle(s) | 1.22 ± 0.55 | −0.24 (−0.47, −0.01) | 0.0397* |
| Ovarian stimulation protocols | |||
| GnRH-a long protocol | 1275 (63.43%) | Ref | |
| Antagonist protocol | 735 (36.57%) | −0.14 (−0.30, 0.03) | 0.0982 |
| Dosage of gonadotropins (100 IU) | 22.89 ± 11.17 | −0.00 (−0.01, 0.00) | 0.4788 |
| Stimulation duration (days) | 11.57 ± 2.20 | 0.00 (−0.03, 0.04) | 0.7997 |
| E2 level on hCG day (100 pg/ml) | 29.98 ± 12.71 | 0.00 (−0.00, 0.01) | 0.3504 |
| Number of oocytes retrieved | 9.66 ± 3.83 | 0.01 (−0.03, 0.04) | 0.6245 |
| Fertilization method | |||
| IVF | 1331 (66.22%) | Ref | |
| ICSI | 580 (28.86%) | 0.12 (−0.19, 0.43) | 0.4520 |
| IVF + ICSI | 99 (4.93%) | −0.10 (−0.76, 0.56) | 0.7659 |
| Stage embryo transferred | |||
| D3 | 1673 (83.23%) | Ref | |
| D5 | 337 (16.77%) | 0.09 (−0.30, 0.49) | 0.6469 |
| Number of embryos transferred | |||
| 1 | 550 (27.36%) | Ref | |
| 2 | 1455 (72.39%) | −0.11 (−0.43, 0.20) | 0.4786 |
| 3 | 5 (0.25%) | 1.60 (−1.92, 5.12) | 0.3740 |
| Endometrial thickness (mm) | 9.97 ± 1.54 | 0.07 (0.02, 0.12) | 0.0067* |
| 6.00–8.90 mm (n = 378) | 378 (18.81%) | Ref | |
| 9.00–9.90 mm (n = 444) | 444 (22.09%) | 0.22 (−0.01, 0.46) | 0.0659 |
| 10.00–10.90 mm (n = 541) | 541 (26.92%) | 0.32 (0.09, 0.55) | 0.0055* |
| >11.00 mm (n = 647) | 647 (32.19%) | 0.34 (0.12, 0.56) | 0.0021* |
| Endometrial type | |||
| A | 30 (1.49%) | Ref | |
| A-B | 107 (5.32%) | 0.10 (−1.14, 1.34) | 0.8739 |
| B | 620 (30.85%) | −0.09 (−1.17, 0.98) | 0.8686 |
| B-C | 1109 (55.17%) | −0.28 (−1.34, 0.79) | 0.6075 |
| C | 144 (7.16%) | −1.15 (−2.33, 0.02) | 0.0555 |
| Gender of newborn | |||
| Male | 1022 (50.85%) | Ref | |
| Female | 988 (49.15%) | 0.29 (0.01, 0.56) | 0.0391* |
AMH: anti-Müllerian hormone; E2: estrogen; GNRH-a: GNRH agonist; Ref, reference group; SD, standard deviation; CI, confidence interval.
*
Statistically significant, with P < 0.05.