Table 3.
Hazard Ratios of the Association of Trimester of Initiation of Prenatal DES Exposure and Risk of Uterine Leiomyomata Among 102,164 Members of the US Nurses' Health Study II, 1989–2007
| DES Exposure | No. of Cases | Person-years | Basic HRa | 95% CI | Fully Adjusted HRb | 95% CI |
|---|---|---|---|---|---|---|
| No | 11,593 | 1,252,388 | 1.00 | Referent | 1.00 | Referent |
| Yes | ||||||
| Trimester unknown | 81 | 7,360 | 1.14 | 0.92, 1.42 | 1.05 | 0.84, 1.31 |
| First trimester | 134 | 11,186 | 1.24 | 1.05, 1.47 | 1.21 | 1.02, 1.43 |
| Second trimester | 17 | 1,741 | 1.02 | 0.64, 1.65 | 0.95 | 0.59, 1.43 |
| Third trimester | 6 | 668 | 0.90 | 0.41, 2.02 | 0.84 | 0.38, 1.88 |
Abbreviations: CI, confidence interval; DES, diethylstilbestrol; HR, hazard ratio.
a Adjusted for age and calendar time.
b Additionally adjusted for race, current body mass index (weight (kg)/height (m)2), smoking status, physical examination in the past 2 years (yes/no), parity, oral contraceptive use, age at menarche, age at first and last births, time since last birth, total months of exclusive breastfeeding, infertility, antihypertensive medication use, and blood pressure.