Table 3.

Univariate and multivariate analyses of early pregnancy loss and live births in fresh ET cycles.

	n	Crude OR	95% CI	P value	Adjusted OR	95% CI	P value
Early pregnancy loss regression a
Age (years)
<35 (Ref)	2626	–	–	–	–	–	–
35–39	367	2.096	1.564–2.810	<0.001	2.026	1.508–2.722	<0.001
≥40	17	3.841	1.342–10.989	0.012	3.553	1.232–10.244	0.019
LH on the day of the COS initiation day (mIU/mL)
≥1.5 (Ref)	1044	–	–	–	–	–	–
<1	918	1.518	1.134–2.032	0.005	1.429	1.065–1.919	0.018
1–1.49	1048	1.436	1.079–1.910	0.013	1.389	1.041–1.853	0.026
Endometrial thickness on the day of the hCG trigger (mm)
<10 (Ref)	408	–	–	–	–	–	–
10–12	1507	0.657	0.478–0.903	0.010	0.652	0.472–0.900	0.009
≥13	1095	0.655	0.468–0.915	0.013	0.663	0.473–0.930	0.017
Number of fresh transferred embryos
1 (Ref)	183	–	–	–	–	–	–
2	2827	0.580	0.387–0.869	0.008	0.619	0.411–0.933	0.022
Live-birth regression b
Age (years)
< 35 (Ref)	5263	–	–	–	–	–	–
35–39	949	0.547	0.470–0.636	<0.001	0.592	0.506–0.693	<0.001
≥40	67	0.277	0.145–0.530	<0.001	0.292	0.151–0.566	<0.001
BMI
≥25 (Ref)	1004	–	–	–	–	–	–
< 18.5	624	1.529	1.245–1.877	<0.001	1.426	1.153–1.765	0.001
18.5–24.9	4651	1.284	1.113–1.482	0.001	1.245	1.074–1.445	0.004
Cause of infertility
Primary infertility (Ref)	2775	–	–	–	–	–	–
Secondary infertility	3504	1.016	0.917–1.125	0.765	1.164	1.045–1.296	0.006
Number of available embryos for ET
<4 (Ref)	2457	–	–	–	–	–	–
4–6	2961	1.517	1.357–1.695	<0.001	1.292	1.147–1.454	<0.001
≥7	861	1.701	1.452–1.993	<0.001	1.409	1.192–1.664	<0.001
LH on the day of the hCG trigger (mIU/mL)
< 0.5 (Ref)	1483	–	–	–	–	–	–
0.5–0.79	2432	1.288	1.125–1.475	<0.001	1.234	1.074–1.419	0.003
≥0.8	2364	1.536	1.342–1.759	<0.001	1.476	1.284–1.697	<0.001
Progesterone on the day of the hCG trigger (ng/mL)
≥1.3 (Ref)	1738	–	–	–	–	–	–
< 0.8	2198	1.283	1.127–1.461	<0.001	1.363	1.191–1.56	<0.001
0.8–1.29	2343	1.241	1.092–1.412	0.001	1.300	1.138–1.484	<0.001
Endometrial thickness on the day of the hCG trigger (mm)
<10 (Ref)	1042	–	–	–	–	–	–
10–12	3230	1.503	1.292–1.748	<0.001	1.489	1.276–1.739	<0.001
≥13	2007	1.999	1.704–2.345	<0.001	1.980	1.679–2.334	<0.001
Number of embryos transferred
1 (Ref)	648	–	–	–	–	–	–
2	5631	2.566	2.111–3.118	<0.001	1.984	1.615–2.437	<0.001
Transfer of at least 1 high-quality embryo
No (Ref)	820			–			–
Yes	5459	1.923	1.632–2.266	<0.001	1.578	1.326–1.877	<0.001
LH on the day of the COS initiation (mIU/mL)
≥1.5 (Ref)	2097	–	–	–	–	–	–
<1	1960	0.827	0.729–0.938	0.003	–	–	0.259
1–1.49	2222	0.841	0.744–0.949	0.005	–	–	0.145

^aAdjusted by age, LH on the day of COS initiation; endometrial thickness on the day of the hCG trigger; and the number of fresh transferred embryos.

^bAdjusted by age, BMI, cause of infertility, LH and progesterone concentrations; endometrial thickness on the day of the hCG trigger; number of embryos transferred; transfer of at least 1 high-quality embryo; and number of available embryos for ET.

OR, odds ratio; CI, confidence interval; BMI, body mass index; LH, luteinizing hormone; hCG, human chorionic gonadotrophin.