Table 3.

FET cycle characteristics.

	Transdermal group N = 119	Vaginal group N = 199	p
Endometrial thickness on day 10 ± 1 of treatment (mm)	9.9 ± 2.1	9.3 ± 2.3	0.03
Ultrasound reassessment for endometrial thickness < 8 mm at day 10 ± 1 of treatment	12 (10.1)	61 (30.6)	< 0.001
FET performed with endometrial thickness < 8 mm	3 (2.5)	16 (8)	0.04
Mean duration of treatment (days)	13.6 ± 2.7	15.5 ± 3.2	< 0.001
Estradiol level on day of first ultrasound (pg/mL)	268 ± 454	1332 ± 769	< 0.001
LH level on day of first ultrasound (mIU/mL)	12.1 ± 16.5	5 ± 7.5	< 0.001
Progesterone level on day of first ultrasound (ng/mL)	0.6 ± 1.3	0.5 ± 1.4	0,61
Canceled cycles	15 (12.6)	17 (8.5)	0.24
• Spontaneous ovulation	9 (7.6)	4 (2)	0.02
• Insufficient endometrial thickness	1 (0.8)b	3 (1.5)c	1
• Loss of embryo viability during thawing	2 (1.7)	3 (1.5)	1
• Other a	3 (2.5)	7 (3.5)	0.62

Data are expressed as n (%) or mean ± standard deviation.

^aThese cancelations were due to fever occurring during treatment, deep pelvic pain secondary to endometriosis, or a history of recent travel to a region with risk of Zika virus endemic area.

^bIdiopathic thin endometrium.

^cNo etiology was found for the thin endometrium in two of these patients. One patient had a positive history of synechia that occurred following a septum resection, and was hysteroscopically treated.