Low Estradiol Level and Endometrial Thickness on the Day of Endometrial Transformation Influence Clinical Pregnancy After Intrauterine Insemination

Figures & data

Table 1 Demographics and Clinical Characteristics of Infertility Patients in This Study

Variables	Number/Mean±SD	Percentage
Number of cycles	1464
Maternal age (years)
≤35	1296	88.5%
>35	168	11.5%
Paternal age (years)
≤35	1113	76.0%
>35	351	24.0%
Cycle type
Natural cycle (NC)	184	12.6%
Ovulation induction cycle	1280	87.4%
Hormone level on the day of endometrial transformation
Estradiol (E2) (pg/mL)	581.15±577.33
Luteinizing hormone (LH) (mIU/mL)	20.10±17.66
Progesterone (P) (ng/mL)	0.79±0.82
Endometrial thickness on the day of endometrial transformation (mm)
<8	298	20.4%
8–13	1121	76.6%
>13	45	3.1%
Forward motile sperm concentration after treatment (×10^6/mL)
<30	772	52.7%
≥30	692	47.3%
Reproductive outcomes
Clinical pregnancy	268	18.3%
Pregnancy failure	1170	79.9%
Biochemical pregnancy	26	1.8%
Premature birth
No	169	87.1%
Yes	25	12.9%

Table 2 Comparison of Characteristics Between Clinical Pregnancy and Pregnancy Failure Groups Among Infertility Patients Performed IUI

Variables	Clinical pregnancy	Pregnancy failure	P value
Number of cycles	268	1170
Maternal age (years) (n, %)
≤35	246 (91.8%)	1029 (87.9%)	0.087
>35	22 (8.2%)	141 (12.1%)
Paternal age (years) (n, %)
≤35	215 (80.2%)	882 (75.4%)	0.095
>35	53 (19.8%)	288 (24.6%)
Cycle type (n, %)
Natural cycle (NC)	28 (10.4%)	153 (13.1%)	0.263
Ovulation induction cycle	240 (89.6%)	1017 (86.9%)
Hormone level on the day of endometrial transformation
Estradiol (E2) (pg/mL)	658.79±656.02	561.21±558.83	0.025
Luteinizing hormone (LH) (mIU/mL)	19.19±15.60	20.33±18.20	0.342
Progesterone (P) (ng/mL)	0.84±0.95	0.77±0.80	0.217
Endometrial thickness on the day of endometrial transformation (mm) (n, %)
<8	35 (13.1%)	258 (22.1%)	0.002
8–13	223 (83.2%)	878 (75.0%)
>13	10 (3.7%)	34 (2.9%)
Forward motile sperm concentration after treatment (×10^6/mL) (n, %)
<30	148 (55.2%)	610 (52.1%)	0.378
≥30	120 (44.8%)	560 (47.9%)

Table 3 Comparison of Demographic and Clinical Characteristics of Full-Term Birth Group and Premature Birth Group

Variables	Full-term birth	Premature birth	P value
Number of cycles	169	25
Maternal age (years) (n, %)
≤35	157 (92.9%)	24 (96.0%)	1.000
>35	12 (7.1%)	1 (4.0%)
Paternal age (years) (n, %)
≤35	135 (79.9%)	20 (80.0%)	1.000
>35	34 (20.1%)	5 (20.0%)
Cycle type (n, %)
Natural cycle (NC)	22 (13.0%)	0 (0)	0.084
Ovulation induction cycle	147 (87.0%)	25 (100.0%)
Hormone level on the day of endometrial transformation
Estradiol (E2) (pg/mL)	625.00±659.17	708.47±520.09	0.546
Luteinizing hormone (LH) (mIU/mL)	19.85±16.50	18.22±12.21	0.635
Progesterone (P) (ng/mL)	0.78±0.70	0.92±0.93	0.371
Endometrial thickness on the day of endometrial transformation (mm) (n, %)
<8	23 (13.6%)	3 (12.0%)	1.000
8–13	140 (82.8%)	21 (84.0%)
>13	6 (3.6%)	1 (4.0%)
Forward motile sperm concentration after treatment (×10^6/mL) (n, %)
<30	88 (52.1%)	16 (64.0%)	0.290
≥30	81 (47.9%)	9 (36.0%)

Table 4 Logistic Regression Analysis of Risk of Pregnancy Failure and Preterm Birth After IUI

Variables	Pregnancy failure				Preterm birth
	Univariate analysis		Multivariate analysis		Univariate analysis		Multivariate analysis
	Crude OR (95% CI)	P value	Adjusted OR (95% CI)	P value	Crude OR (95% CI)	P value	Adjusted OR (95% CI)	P value
Maternal age (years)
≤35	1.000 (reference)		1.000 (reference)		1.000 (reference)		1.000 (reference)
>35	1.555 (0.972–2.486)	0.065	1.348 (0.762–2.383)	0.304	0.545 (0.068–4.384)	0.568	0.476 (0.046–4.928)	0.534
Paternal age (years)
≤35	1.000 (reference)		1.000 (reference)		1.000 (reference)		1.000 (reference)
>35	1.346 (0.970–1.869)	0.076	1.157 (0.776–1.724)	0.474	0.993 (0.347–2.836)	0.989	1.294 (0.397–4.213)	0.669
Cycle type
Natural cycle	1.000 (reference)		1.000 (reference)		1.000 (reference)		1.000 (reference)
Ovulation induction cycle	0.778 (0.508–1.191)	0.248	0.782 (0.507–1.206)	0.267	–	0.998	–	0.998
Estradiol (E2) level on the day of endometrial transformation (pg/mL)
≥238.3	1.000 (reference)		1.000 (reference)		1.000 (reference)		1.000 (reference)
<238.3	1.531 (1.119–2.097)	0.008	1.493 (1.086–2.052)	0.014	0.300 (0.068–1.329)	0.113	0.296 (0.065–1.347)	0.115
Endometrial thickness on the day of endometrial transformation (mm)
8–13	1.000 (reference)		1.000 (reference)		1.000 (reference)		1.000 (reference)
<8	1.866 (1.274–2.734)	0.001	1.886 (1.284–2.771)	0.001	0.870 (0.240–3.151)	0.832	0.867 (0.229–3.275)	0.833
>13	0.869 (0.424–1.782)	0.702	0.851 (0.413–1.754)	0.663	1.111 (0.127–9.694)	0.924	0.884 (0.097–8.082)	0.913
Forward motile sperm concentration after treatment (×10^6/mL)
≥30	1.000 (reference)		1.000 (reference)		1.000 (reference)		1.000 (reference)
<30	0.885 (0.678–1.154)	0.366	0.862 (0.659–1.129)	0.281	1.636 (0.685–3.908)	0.268	1.733 (0.712–4.221)	0.226

Data Sharing Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.