Table 4.
Kaplan-Meier intention-to-treat life table analysis of pregnancy
|
At risk (effective sample size) |
Number of pregnancies*(failure) |
Number of discontinuations (censored) |
Probability |
Cumulative probability |
|||
|---|---|---|---|---|---|---|---|
| Pregnancy (failure) | No pregnancy (survival) | No pregnancy (95% CI)† (survival) | Pregnancy (failure) | ||||
| 1 | 2265 | 2 | 143 | 0·0009 | 0·9991 | 0·9987 (0·9959–0·9996) | 0·0013 |
| 2 | 2119 | 7 | 94 | 0·0033 | 0·9967 | 0·9954 (0·9914–0·9975) | 0·0046 |
| 3 | 2018 | 5 | 122 | 0·0025 | 0·9975 | 0·9929 (0·9883–0·9957) | 0·0071 |
| 4 | 1891 | 2 | 76 | 0·0005 | 0·9995 | 0·9924 (0·9876–0·9953) | 0·0076 |
| 5 | 1814 | 4 | 69 | 0·0022 | 0·9978 | 0·9902 (0·9848–0·9937) | 0·0098 |
| 6 | 1741 | 2 | 119 | 0·0011 | 0·9989 | 0·9891 (0·9834–0·9928) | 0·0109 |
| 7 | 1620 | 0 | 76 | 0·0000 | 1·0000 | 0·9891 (0·9834–0·9928) | 0·0109 |
| 8 | 1544 | 3 | 134 | 0·0019 | 0·9981 | 0·9871 (0·9810–0·9913) | 0·0129 |
| 9 | 1407 | 3 | 138 | 0·0021 | 0·9979 | 0·9850 (0·9783–0·9897) | 0·0150 |
| 10 | 1266 | 5 | 126 | 0·0032 | 0·9968 | 0·9819 (0·9744–0·9873) | 0·0181 |
| 11 | 1136 | 3 | 100 | 0·0026 | 0·9974 | 0·9793 (0·9711–0·9852) | 0·0207 |
| 12 | 1033 | 3 | 64 | 0·0029 | 0·9971 | 0·9765 (0·9675–0·9830) | 0·0235 |
| 13 | 966 | 2 | 964 | 0·0021 | 0·9979 | 0·9745 (0·9649–0·9814) | 0·0255 |
*
Only pregnancies occurring within 7 days of last contraceptive vaginal system use were included.
†
The 95% CI was calculated with complementary log-log transformation.