Table 4.

Patients characteristics and perinatal outcomes between the two groups with singleton live birth

	Group 1 (101)	Group 2 (400)	P
Age (year)	29.30 ± 3.56	30.39 ± 3.90	0.018*
BMI (kg/m2)	21.71 ± 3.02	21.60 ± 2.82	0.937
Endometrial thickness (mm)	9.41 ± 1.61	9.44 ± 1.41	0.394
The indications for IVF/ICSI
Pelvic and tubal factor	53 (52.5%)	227 (56.8%)	0.439
Male infertility	29 (28.7%)	164 (41.0%)	0.023*
Endometriosis	3 (3.0%)	33 (8.3%)	0.066
PCOS	19 (18.8%)	53 (13.3%)	0.155
> 20 oocytes retrieved	44 (43.6%)	176 (44.0%)	0.937
progesterone> 1.5 ng/ml	36 (35.6%)	123 (30.8%)	0.345
Protocol for COH			0.096
Agonist	87 (86.1%)	315 (78.8%)
Antagonist	14 (13.9%)	85 (21.2%)
Method of fertilization			0.025*
IVF	54 (53.5%)	262 (65.5%)
ICSI	47 (46.5%)	138 (34.5%)
Gestational age (day)	272.13 ± 8.09	271.75 ± 10.88	0.928
Birth weight(g)	3327.43 ± 456.84	3372.40 ± 519.11	0.456
Delivery mode			0.513
Natural labor	10 (9.9%)	49 (12.3%)
Caesarean delivery	91 (90.1%)	351 (87.7%)
Gender			0.507
Male	63 (62.4%)	235 (58.8%)
Female	38 (37.6%)	165 (41.2%)
Abnormal perinatal outcomes
Preterm birth<37 weeks	4 (4.0%)	29 (7.3%)	0.234
Gestational hypertension	7 (6.9%)	29 (7.3%)	0.912
GDM	8 (7.9%)	39 (9.8%)	0.573
Placenta previa	4 (4.0%)	13 (3.3%)	0.758
Fetal malformation	2 (2.0%)	6 (1.5%)	0.665
Macrosomia≥4000 g	3 (3.0%)	42 (10.5%)	0.018*
Low birthweight<2500 g	4 (4.0%)	18 (4.5%)	1.000

Note: 501 FET cycles with singleton live birth were included. In Group 1, three patients with twin live births were excluded. In Group 2, two patients with twin live births and one patient without perinatal outcome were excluded. Continuous data: mean ± SD. Categorical data: n (rate). Mann-Whitney tests were used in the continuous data and chi square tests or Fisher exact tests were used in the categorical data. *, P<0.05

IVF, in vitro fertilization, ICSI intracytoplasmic sperm injection, GDM gestational diabetes mellitus

PCOS polycystic ovary syndrome, COH controlled ovarian hyperstimulation