Table 1.
Age‐Standardized Baseline (1989) Characteristics Among 103 729 Women in the Nurses' Health Study II, by Infertility History Across Follow‐Up*
| Characteristics in 1989 | Ever reported infertility | |
|---|---|---|
| No | Yes | |
| No. | 75 118 | 28 611 |
| Age, y† | 34.8 (4.7) | 34.9 (4.6) |
| Race, White, % | 92.2 | 91.2 |
| Ever married, % | 92.6 | 90.2 |
| Body mass index at age 18 y, kg/m2 | 21.1 (3) | 21.3 (3.6) |
| Body mass index, kg/m2, % | ||
| <18.5 | 1.3 | 1.8 |
| 18.5–24.9 | 39.5 | 36.6 |
| 25–29.9 | 30.9 | 29.6 |
| ≥30 | 28.3 | 32.0 |
| Past/current oral contraceptive use, % | 88.7 | 89.1 |
| Total physical activity, mean (SD), h/wk | 3.3 (4.9) | 3.4 (5.1) |
| Regular aspirin user in 1989,‡ % | 10.9 | 10.7 |
| History of cigarette smoking, % | ||
| Never | 66.3 | 65.3 |
| Past | 21.0 | 19.6 |
| Current 1–34 cigarettes/d | 11.6 | 13.8 |
| Current ≥35 cigarettes/d | 1.0 | 1.2 |
| Parental history of myocardial infarction or stroke, % | 14.5 | 16.0 |
| Gravidity, mean (SD) | 2.4 (1.4) | 1.8 (1.6) |
| Parous, % | 85.0 | 61.8 |
| Gestational diabetes,§ % | 3.6 | 5.6 |
| Hypertensive disorders of pregnancy,§ % | 14.2 | 19.6 |
| Breastfeeding duration,§ mo | 13.1 (13.4) | 11.3 (11.8) |
| Causes of infertility, no. (%)|| | ||
| Cause not investigated | … | 7761 (27.1) |
| Among those investigated | ||
| Ovulatory disorder | … | 8149 (39.1) |
| Endometriosis | … | 4497 (21.5) |
| Cervical mucus disorder | … | 1567 (7.6) |
| Tubal blockage | … | 3073 (14.7) |
| Male factor/spouse | … | 5353 (25.7) |
| Other cause | … | 4544 (21.8) |
| Cause not found | … | 6356 (30.5) |
*
Values are given as means (SDs) or percentages and are standardized to the age distribution of the study population.
†
Value is not age‐adjusted.
‡
Aspirin or aspirin‐containing products used at least once per week in the past 2 years.
§
Among parous participants.
||
Attributed causes of infertility, which were not mutually exclusive, were gathered at baseline and during follow‐up among those who reported having tried to conceive unsuccessfully for at least 12 months up to age 40. N=1011 (3.5%) did not report if they had had an investigation or not or what the cause was attributed to if investigated.