Table 2.
Association of contraceptive method at first intercourse with pregnancy reported at age 16 follow-up, RIPPLE and SHARE data sets
| N (column %) in contraception group | N (row %) pregnant | Stage 1 |
Stage 2 (1 + adjustment for agent FS) |
Stage 3 (1 + adjustment for deprivation, expectations and number of partners) |
||||
|---|---|---|---|---|---|---|---|---|
| OR | 95% CI | OR | 95% CI | OR | 95% CI | |||
| All girls | ||||||||
| Total | 1,952 (100) | 163 (10) | ||||||
| Condom only | 1,109 (54) | 67 (7) | 1.00 | 1.00 | 1.00 | |||
| Dual (condom and OC) | 198 (11) | 9 (6) | 0.82 | (0.45–1.52) | 0.80 | (0.43–1.51)⁎ | 0.80 | (0.43–1.48)⁎ |
| OC only | 73 (4) | 11 (16) | 2.44 | (1.29–4.60)⁎ | 2.49 | (1.27–4.88)⁎ | 2.17 | (1.12–4.19)⁎ |
| Emergency contraception | 72 (4) | 4 (5) | 0.67 | (0.23–1.94) | 0.66 | (0.22–1.93) | 0.67 | (0.23–1.98) |
| No effective method | 380 (21) | 61 (18) | 2.97 | (2.12–4.15)⁎ | 2.61 | (1.83–3.71)⁎ | 2.56 | (1.81–3.63)⁎ |
| Missing | 120 (6) | 11 (10) | 1.61 | (0.86–3.02) | 0.66 | (0.22–1.97) | 1.50 | (0.79–2.83) |
| R2 (null model = .01) | 0.07 | 0.26 | 0.12 | |||||
| RIPPLE girls | ||||||||
| Total | 1,109 (100) | 86 (9) | ||||||
| Condom only | 617 (54) | 34 (6) | 1.00 | 1.00 | 1.00 | |||
| Dual (condom and OC) | 132 (12) | 7 (6) | 1.06 | (0.50–2.23) | 0.97 | (0.45–2.10) | 1.11 | (0.52–2.36) |
| OC only | 39 (4) | 5 (15) | 2.97 | (1.23–7.14)⁎ | 3.15 | (1.26–7.90)⁎ | 3.17 | (1.28–7.85)⁎ |
| Emergency contraception | 33 (3) | 3 (8) | 1.32 | (0.37–4.66) | 1.04 | (0.28–3.87) | 1.45 | (0.41–5.22) |
| No effective method | 179 (17) | 28 (18) | 3.44 | (2.11–5.60)⁎ | 3.26 | (1.94–5.47)⁎ | 2.93 | (1.76–4.87)⁎ |
| Missing | 109 (10) | 9 (10) | 1.70 | (0.85–3.39) | 2.05 | (1.00–4.20) | 1.68 | (0.83–3.41) |
| R2 (null model = .01) | 0.07 | 0.26 | 0.13 | |||||
| SHARE girls | ||||||||
| Total | 843 (100) | 77 (11) | ||||||
| Condom only | 492 (55) | 33 (8) | 1.00 | 1.00 | ||||
| Dual (condom and OC) | 66 (8) | 2 (5) | 0.54 | (0.18–1.64) | 0.63 | (0.20–2.00) | 0.50 | (0.16–1.53) |
| OC only | 34 (4) | 6 (16) | 2.33 | (0.92–5.85) p < .1 | 2.64 | (0.96–7.25) p < .1 | 1.86 | (0.71–4.89) |
| Emergency contraception | 39 (4) | 1 (3) | 0.25 | (0.03–2.17) | 0.30 | (0.03–2.61) | 0.24 | (0.03–2.11) |
| No effective method | 201 (27) | 33 (19) | 2.56 | (1.62–4.05)⁎ | 2.16 | (1.33–3.51)⁎ | 2.16 | (1.34–3.47)⁎ |
| Missing | 11 (1) | 2 (18) | 2.10 | (0.41–10.74) | 1.41 | (0.26–7.70) | 1.71 | (0.30–9.65) |
| R2 (null model = .01) | 0.09 | 0.29 | 0.17 | |||||
OR = odds ratio; CI = confidence interval; OC = oral contraceptive.
⁎
Denotes p < .05. All models adjusted for arm of trial and age in months at follow-up. Combined model also adjusted for study group and interaction term (study × arm of trial).