Table 5 Comparison of the baseline demographic features and true natural cycle characteristics of patients with luteinized unruptured follicle (LUF) or follicular collapse
Characteristics | LUF n = 25 | Follicular collapse n = 153 | P* |
|---|---|---|---|
Age, years | 34.0 (30.5–37.50) | 36.5 (32.0–40.0) | 0.135 |
Body mass index, kg/m2 | 23.4 (22.0–26.1) | 22.7 (20.9–25.8) | 0.305 |
Antral follicle count on Day 2/3, n | 16 (9.5–18.0) | 14 (8–19.0) | 0.539 |
Cause of infertility, n (%) | Â | Â | 0.770 |
 Unexplained infertility | 6 (24.0) | 51 (33.3) |  |
 Male factor | 10 (40.0) | 44 (28.8) |  |
 Advanced maternal age and/or diminished ovarian reserve | 5 (20.0) | 43 (28.1) |  |
 Tubal factor | 1 (4.0) | 5 (3.3) |  |
 Endometriosis | 2 (8.0) | 4 (2.6) |  |
 Monogenic disorders | 1 (4.0) | 6 (3.9) |  |
Duration of infertility, months | 24.0 (16.5–39.0) | 28.5 (15.3–50.0) | 0.889 |
Number of previous IVF cycles, median (minimum-maximum) | 0 (0–3) | 0 (0–8) | 0.615 |
Previous childbirth, n (%) | 7 (28.0) | 28 (18.3) | 0.280 |
Follicular phase length, day | 11.0 (9.5–14.5) | 13.0 (12.0–15.0) | 0.052 |
Follicle diameter one day prior to ovulation, mm | 20.1 (19.2–21.1) | 19.2 (17.8–20.9) | 0.004 |
Peak E2 level, pg/mL | 284.0 (228.0–360.1) | 324.5 (265.0–392.8) | 0.022 |
Peak LH level, IU/L | 39.2 (31.3–54.0) | 47.7 (36.4–59.3) | 0.246 |
Follicular phase peak P4 level, ng/mL | 1.0 (0.9–1.4) | 1.1 (0.9–1.4) | 0.121 |
Endometrial thickness one day prior to ovulation, mm | 10.9 (9.9–11.4) | 10.1 (9.0–11.7) | 0.084 |
Serum P4 concentration on FET-1, ng/mL | 9.3 (5.5–15.4) | 13.6 (10.3–17.3) | 0.002 |