Table 3 Comparison of the cycle characteristics of the CC + letrozole and CC-alone groups

Progestin withdrawal, n (%)

13 (35.4)

14 (29.8)

0.714

Ultrasound cycle day, median (min, max)

13 (11, 15)

13 (12, 16)

0.940

Reported urine LH surge, n (%)

29 (60.4)

34 (72)

0.311

Cycle day of LH surge

 median (min, max)

(n = 29)

16 (12, 21)

(n = 34)

15 (12, 18)

0.191

No. of follicles > 10 mm, median (min, max)

1 (0, 5)

1 (0, 5)

0.815

No. of follicles > 14 mm, median (min, max)

1 (0, 5)

1 (0, 5)

0.919

No. of women with follicle > 14 mm, n (%)

31 (64.6)

30 (63.8)

1.000

Largest follicle size (mm), median (min, max)

16.75 (0, 35)

15.50 (5.5, 35.5)

0.687

Endometrial lining thickness (mm), median (min, max)

6.85 (3.1, 13.5)

7.40 (3.6, 12.6)

0.171

Cycle day progesterone level obtained, median (min, max)

22 (19, 28)

22 (19, 28)

0.768

Progesterone level, ng/ml, median (min, max)

18.40 (0.05, 60)

17.90 (0.05, 60)

0.387

Cycle characteristics of those who ovulated

Letrozole + CC group

(n = 37)

Clomiphene citrate group

(n = 33)

 Progestin withdrawal, n (%)

10 (27)

9 (27.3)

1.000

 Ultrasound cycle day, median (min, max)

13 (11, 15)

13 (12, 15)

0.197

 Reported urine LH surge, n (%)

28 (75.7)

28 (84.8)

0.510

 Cycle day of LH surge, median (min, max)

16 (12, 21)

15 (12, 18)

0.379

 No. of follicles > 10 mm, median (min, max)

2 (0, 5)

2 (0, 5)

0.922

 No. of follicles > 14 mm, median (min, max)

1 (0, 5)

1 (0, 5)

0.712

 No. of women with follicles > 14 mm, n (%)

29 (78.4)

27 (81.8)

0.952

 Largest follicle size, mm, median (min, max)

17.6 (0, 35)

20.5 (9.5, 35.5)

0.572

 Endometrial lining thickness, mm, median (min, max)

7 (3.5, 13.5)

8 (3.6, 12.6)

0.441

 Cycle day progesterone level obtained, median (min, max)

22 (19, 28)

22 (19, 28)

0.990

 Progesterone level, ng/ml, median (min, max)

27.80 (3.5, 60)

25.10 (3.28, 60)

0.860