Table 1 Characteristics of participants (N = 1487).

Age (year)

31.9 ± 7.1

33.5 ± 6.1

31.6 ± 7.2

< 0.001

Race (%)

0.509

 Mexican American

211 (14.2)

30 (15.0)

181 (14.1)

 Other Hispanic

155 (10.4)

23 (11.5)

132 (10.3)

 Non-Hispanic White

432 (29.1)

66 (33.0)

366 (28.4)

 Non-Hispanic Black

417 (28.0)

49 (24.5)

368 (28.6)

 Other race

272 (18.3)

32 (16.0)

240 (18.6)

Education level (%)

0.243

 Below high school

197 (13.2)

34 (17.0)

163 (12.7)

 High school

309 (20.8)

40 (20.0)

269 (20.9)

 Above high school

981 (66.0)

126 (63.0)

855 (66.4)

Marital status (%)

< 0.001

 Married or living with partner

825 (55.5)

145 (72.5)

680 (52.8)

 Widowed, divorced, and separated

123 (8.3)

17 (8.5)

106 (8.2)

 Never married

539 (36.2)

38 (19.0)

501 (38.9)

Family income (%)

0.046

 Low

476 (36.4)

50 (28.1)

426 (37.7)

 Medium

480 (36.7)

75 (42.1)

405 (35.8)

 High

353 (27.0)

53 (29.8)

300 (26.5)

Body mass index (kg/m²) (%)

0.081

 < 25

476 (32.0)

55 (27.5)

421 (32.7)

 25 ~ 30

354 (23.8)

42 (21.0)

312 (24.2)

 ≥ 30

657 (44.2)

103 (51.5)

554 (43.0)

Drink status (%)

0.61

 No

141 (9.5)

17 (8.5)

124 (9.6)

 Yes

1346 (90.5)

183 (91.5)

1163 (90.4)

Smoking status (%)

0.003

 Never

1049 (70.5)

121 (60.5)

928 (72.1)

 Former

188 (12.6)

31 (15.5)

157 (12.2)

 Current

250 (16.8)

48 (24.0)

202 (15.7)

Trouble sleeping (%)

< 0.001

 No

1153 (77.5)

137 (68.5)

1016 (78.9)

 Yes

334 (22.5)

63 (31.5)

271 (21.1)

Menstrual cycle regularity (%)

0.858

 No

107 (7.2)

15 (7.5)

92 (7.1)

 Yes

1380 (92.8)

185 (92.5)

1195 (92.9)

Ever treated for a pelvic infection/PID (%)

0.285

 No

1399 (94.6)

186 (93.0)

1213 (94.8)

 Yes

80 (5.4)

14 (7.0)

66 (5.20)

RFM

41.2 ± 6.6

42.8 ± 6.5

40.9 ± 6.6

< 0.001