Table 3.
Association of reproductive factors prior to pregnancy and risk of ectopic pregnancy the Nurses’ Health Study II (1990-2009).
| Pre-pregnancy Characteristics | Ectopic/Total (%) |
Unadjusted RR (95% CI) |
Adjusted RRa (95% CI) |
|---|---|---|---|
| Age at first OC Use (n=40,094) | |||
| Never | 36/6021 (0.6) | 1.0 (REF) | 1.0 (REF) |
| 13-16 yrs | 47/2488 (1.9) | 3.16 (2.05, 4.86) | 2.64 (1.70, 4.09) |
| 17-20 yrs | 167/14800 (1.1) | 1.89 (1.32, 2.70) | 1.67 (1.16, 2.41) |
| 21-24 yrs | 102/11162 (0.9) | 1.53 (1.05, 2.23) | 1.51 (1.03, 2.21) |
| 25+ yrs | 49/5623 (0.9) | 1.46 (0.95, 2.24) | 1.46 (0.95, 2.24) |
| Contraceptive Use (n=41,440) | |||
| None | 226/19978 (1.1) | 1.0 (REF) | 1.0 (REF) |
| Condom | 55/9825 (0.6) | 0.57 (0.43, 0.76) | 0.72 (0.53, 0.97) |
| Oral Contraceptives | 33/5384 (0.6) | 0.55 (0.39, 0.80) | 0.70 (0.48, 1.02) |
| Diaphragm/Cervical Cap | 38/5290 (0.7) | 0.82 (0.58, 1.17) | 1.04 (0.72, 1.48) |
| Foam or Sponge | 27/3850 (0.7) | 0.81 (0.53, 1.22) | 0.88 (0.58, 1.34) |
| Rhythm Method | 23/4171 (0.6) | 0.65 (0.43, 0.99) | 0.80 (0.52, 1.22) |
| Vasectomy | 3/371 (0.8) | 0.84 (0.32, 2.24) | 1.03 (0.39, 2.72) |
| Tubal Ligation | 41/290 (14.1) | 12.66 (9.34, 17.16) | 16.27 (11.76, 22.53) |
| Intrauterine Device | 9/259 (3.5) | 3.13 (1.63, 6.02) | 3.99 (2.06, 7.72) |
| History of Infertility (n= 40,296) | |||
| No | 242/33398 (0.7) | 1.0 (REF) | 1.0 (REF) |
| Yes | 157/6898 (2.3) | 3.14 (2.57, 3.83) | 3.03 (2.48, 3.71) |
| History of Infertility (n= 40,296) | |||
| No | 242/33398 (0.7) | 1.0 (REF) | 1.0 (REF) |
| Yes, Tubal | 43/529 (8.1) | 7.67 (5.49, 10.71) | 7.28 (5.24, 10.11) |
| Yes, Ovulatory Disorder | 50/1914 (2.6) | 2.23 (1.61, 3.09) | 2.31 (1.67, 3.20) |
| Yes, Endometriosis | 18/907 (2.0) | 0.94 (0.57, 1.53) | 0.87 (0.53, 1.42) |
| Yes, Cervical Mucous Factors | 14/392 (3.6) | 1.64 (0.96, 2.80) | 1.76 (1.03, 3.01) |
| Yes, Spousal | 13/1041 (1.3) | 0.73 (0.41, 1.27) | 0.73 (0.42, 1.28) |
| Yes, Unexplained | 31/1586 (2.0) | 2.21 (1.54, 3.18) | 2.15 (1.50, 3.10) |
| Yes, No Diagnosis Reported | 38/2046 (1.9) | 2.34 (1.67, 3.30) | 2.19 (1.55, 3.08) |
| History of Ectopic Pregnancy (n=41,440) | |||
| No | 339/40712 (0.8) | 1.0 (REF) | 1.0 (REF) |
| Yes | 72/728 (9.9) | 11.88 (9.31, 15.15) | 8.45 (6.57, 10.86) |
| History of Induced Abortion (n=41,440) | |||
| No | 333/34368 (1.0) | 1.0 (REF) | 1.0 (REF) |
| Yes | 78/7072 (1.1) | 1.14 (0.89, 1.45) | 0.98 (0.76, 1.26) |
| History of Spontaneous Abortion (n=41,440) | |||
| No | 283/29446 (1.0) | 1.0 (REF) | 1.0 (REF) |
| Yes | 128/11994 (1.1) | 1.11 (0.90, 1.37) | 0.98 (0.79, 1.21) |
| In Utero Exposure to DES (n=41,440) | |||
| No | 377/40580 (0.9) | 1.0 (REF) | 1.0 (REF) |
| Yes | 34/860 (4.0) | 4.26 (3.02, 6.01) | 3.55 (2.51, 5.01) |
Abbreviations: BMI, body mass index; DES, diethylstilbestrol; OC, oral contraceptive; RR, risk ratio.
a
Models were run adjusting for age, race, smoking status, alcohol intake, BMI, history of infertility, age at first oral contraceptive use, and multivitamin use.