Table 1.
Baseline characteristics of study participants by history of infertility, miscarriage, and stillbirth. Data are numbers (%)
| Characteristics | Infertility (n=94 286) | Miscarriage (n=550 853) | Stillbirth (n=540 638) | |||||
|---|---|---|---|---|---|---|---|---|
| Never | Ever | Never | Ever | Never | Ever | |||
| Sample size | 78 055 (82.79) | 16 231 (17.21) | 459 284 (83.38) | 91 569 (16.62) | 515 765 (95.40) | 24 873 (4.60) | ||
| Race or ethnicity | ||||||||
| White | 63 738 (81.66) | 13 804 (85.05) | 177 722 (38.70) | 60 207 (65.75) | 221 459 (42.94) | 6710 (26.98) | ||
| Asian | 13 276 (17.01) | 2160 (13.31) | 275 992 (60.09) | 29 093 (31.77) | 287 215 (55.69) | 17 608 (70.79) | ||
| Others | 1041 (1.33) | 267 (1.65) | 5570 (1.21) | 2269 (2.48) | 7091 (1.37) | 555 (2.23) | ||
| Body mass index | ||||||||
| Underweight | 4051 (5.19) | 917 (5.65) | 13 566 (2.95) | 2490 (2.72) | 13 968 (2.71) | 1429 (5.75) | ||
| Normal | 46 223 (59.22) | 9914 (61.08) | 176 583 (38.45) | 34 955 (38.17) | 197 260 (38.25) | 9453 (38.01) | ||
| Overweight | 20 328 (26.04) | 3895 (24.00) | 186 293 (40.56) | 34 689 (37.88) | 208 466 (40.42) | 9653 (38.81) | ||
| Obese | 7453 (9.55) | 1505 (9.27) | 82 842 (18.04) | 19 435 (21.22) | 96 071 (18.63) | 4338 (17.44) | ||
| Current smoker | ||||||||
| No | 62 816 (80.48) | 12 649 (77.93) | 429 192 (93.45) | 82 966 (90.60) | 480 771 (93.22) | 23 060 (92.71) | ||
| Yes | 15 239 (19.52) | 3582 (22.07) | 30 092 (6.55) | 8603 (9.40) | 34 994 (6.78) | 1813 (7.29) | ||
| Education level | ||||||||
| ≤10 | 23 600 (30.24) | 4397 (27.09) | 320 770 (69.84) | 55 316 (60.41) | 350 177 (67.89) | 20 679 (83.14) | ||
| 11-12 | 18 534 (23.74) | 4113 (25.34) | 63 985 (13.93) | 11 763 (12.85) | 72 174 (13.99) | 1861 (7.48) | ||
| >12 | 35 921 (46.02) | 7721 (47.57) | 74 529 (16.23) | 24 490 (26.74) | 93 414 (18.11) | 2333 (9.38) | ||
| Hypertension | ||||||||
| No | 62 505 (80.08) | 13 373 (82.39) | 317 457 (69.12) | 63 644 (69.50) | 358 816 (69.57) | 14 254 (57.31) | ||
| Yes | 15 550 (19.92) | 2858 (17.61) | 141 827 (30.88) | 27 925 (30.50) | 156 949 (30.43) | 10 619 (42.69) | ||
| Diabetes mellitus | ||||||||
| No | 76 502 (98.06) | 15 862 (97.78) | 438 278 (95.50) | 87 260 (95.43) | 492 462 (95.57) | 23 160 (93.20) | ||
| Yes | 1511 (1.94) | 360 (2.22) | 20 649 (4.50) | 4176 (4.57) | 22 843 (4.43) | 1689 (6.80) | ||
Infertility: women from Australian Longitudinal Study on Women’s Health 1946-51 cohort (ALSWH-mid), Swedish Women’s Lifestyle and Health Study (WLH), United Kingdom MRC National Survey of Health and Development (NSHD), United States Study of Women’s Health Across the Nation (SWAN), Japan Nurses’ Health Study (JNHS), and Utrecht contribution to the European Prospective Investigation into Cancer and Nutrition cohort, Netherlands (Prospect-EPIC) were included. Miscarriage: women from NSHD, SWAN, UK Biobank, China Biobank, and Prospect-EPIC were included. Among the 550 583 women, 67 345 (12.23%) had one miscarriage, 16 101 (2.92%) had two miscarriages, and 8064 (1.46%) had three or more miscarriages. Stillbirth: women from NSHD, SWAN, UK Biobank, China Biobank, and Prospect-EPIC were included. Among the 540 638 women, 19 937 (3.69%) had one stillbirth, and 4924 (0.91%) had two or more stillbirths. Body mass index: for Asian women, the classifications of body mass index are <18.5 (underweight), 18.5-22.9 (normal), 23-27.4 (overweight), and ≥27.5 (obese); for others, the classifications of body mass index are <18.5 (underweight), 18.5-24.9 (normal), 25-29.9 (overweight), and ≥30 (obese).