Table 2.
Reproductive and perinatal outcomes following induced abortion, miscarriage or live birth in first pregnancy
| Outcome in first pregnancy | Crude and adjusted (Adj.) RR (99% CI)* | ||||
| Induced abortion | Live birth | Miscarriage | Induced abortion versus live birth | Induced abortion versus miscarriage | |
| Outcome of second pregnancy | N=120 033 | N=457 477 | N=47 355 | ||
| Live birth | 67 336 (56.1) | 355 674 (77.7) | 36 479 (77.0) | Crude 0.72 (0.71 to 0.73) | Crude 0.72 (0.72 to 0.73) |
| Adj. 0.74 (0.73 to 0.74) | Adj. 0.69 (0.69 to 0.70) | ||||
| Stillbirth | 409 (0.34) | 1406 (0.31) | 247 (0.52) | Crude 1.11 (0.96 to 1.28) | Crude 0.65 (0.53 to 0.80) |
| Adj. 1.06 (0.91 to 1.24) | Adj. 0.58 (0.46 to 0.74) | ||||
| Miscarriage | 7965 (6.6) | 30 669 (6.7) | 6197 (13.1) | Crude 0.99 (0.96 to 1.02) | Crude 0.51 (0.49 to 0.53) |
| Adj. 1.05(1.01 to 1.08) | Adj. 0.56 (0.54 to 0.59) | ||||
| Ectopic pregnancy | 1115 (0.9) | 2939 (0.6) | 499 (1.1) | Crude 1.45 (1.32 to 1.58) | Crude 0.88 (0.77 to 1.01) |
| Adj. 1.36 (1.23 to 1.50) | Adj. 0.83 (0.71 to 0.97) | ||||
| Induced abortion | 43 208 (36.0) | 66 789 (14.6) | 3933 (8.3) | Crude 2.47 (2.43 to 2.50) | Crude 4.33 (4.16 to 4.51) |
| Adj. 2.30 (2.27 to 2.33) | Adj. 4.64 (4.44 to 4.85) | ||||
| Outcome in first pregnancy | Crude and adjusted (Adj.) RR (99% CI)* | ||||||
| Induced abortion | Live birth | Miscarriage | Primigravida | Induced abortion versus live birth | Induced abortion versus miscarriage | Induced abortion versus primigravida | |
| Outcomes in ongoing pregnancies | N=67 745 | N=357 080 | N=36 726 | N=457 477 | |||
| Pre-eclampsia | 1583 (2.3) | 2982 (0.8) | 922 (2.5) | 8649 (1.9) | Crude 2.80 (2.58 to 3.03) | Crude 0.93 (0.84 to 1.03) | Crude 1.24 (1.15 to 1.32) |
| Adj. 2.42 (2.21 to 2.65) | Adj. 0.83 (0.73 to 0.94) | Adj. 1.26 (1.17 to 1.35) | |||||
| Placenta praevia | 385 (0.6) | 1919 (0.5) | 289 (0.8) | 2042 (0.5) | Crude 1.06 (0.92 to 1.22) | Crude 0.72 (0.59 to 0.88) | Crude 1.27 (1.10 to 1.47) |
| Adj. 1.09 (0.93 to 1.28) | Adj. 0.79 (0.62 to 1.01) | Adj. 1.05 (0.91 to 1.22) | |||||
| Abruptio placenta | 339 (0.5) | 1197 (0.3) | 173 (0.5) | 1770 (0.4) | Crude 1.49 (1.27 to 1.75) | Crude 1.06 (0.84 to 1.35) | Crude 1.30 (1.11 to 1.51) |
| Adj. 1.49 (1.25 to 1.77) | Adj. 1.00 (0.76 to 1.32) | Adj. 1.28 (1.10 to 1.50) | |||||
| Induction of labour† | 18 044 (26.6) | 69 482 (19.5) | 10 347 (28.2) | 120 080 (26.3) | Crude 1.37 (1.34 to 1.39) | Crude 0.95 (0.92 to 0.97) | Crude 1.01 (1.00 to 1.03) |
| Adj. 1.33 (1.30 to 1.35) | Adj. 0.98 (0.95 to 1.01) | Adj. 1.00 (0.99 to 1.02) | |||||
| Low birth weight <2500 g‡ | 5385 (8.0) | 16 309 (4.6) | 3101 (8.5) | 28 735 (6.3) | Crude 1.74 (1.67 to 1.81) | Crude 0.94 (0.89 to 1.00) | Crude 1.27 (1.22 to 1.31) |
| Adj. 1.24 (1.17 to 1.31) | Adj. 0.96 (0.90 to 1.03) | Adj. 1.08 (1.04 to 1.13) | |||||
| Outcomes in spontaneous births | N=45 656 | N=255 220 | N=23 751 | N=318 217 | |||
| Spontaneous preterm birth <37 weeks | 4224 (9.3) | 13 453 (5.3) | 2376 (10.0) | 21 891 (6.9) | Crude 1.76 (1.68 to 1.83) | Crude 0.92 (0.86 to 0.97) | Crude 1.35 (1.29 to 1.40) |
| Adj. 1.66 (1.58 to 1.74) | Adj. 0.85 (0.79 to 0.91) | Adj. 1.37 (1.32 to 1.42) | |||||
| Spontaneous very preterm birth <32 weeks | 878 (1.9) | 2157 (0.9) | 513 (2.2) | 4051 (1.3) | Crude 2.28 (2.05 to 2.52) | Crude 0.89 (0.77 to 1.03) | Crude 1.51 (1.37 to 1.66) |
| Adj. 2.20 (1.96 to 2.47) | Adj. 0.83 (0.70 to 0.99) | Adj. 1.57 (1.43 to 1.72) | |||||
Values are n (%) unless otherwise specified. Statistically significant relative risks are shown as bold.
*
Adjusted for maternal age, year of delivery, Carstairs at first pregnancy and interpregnancy interval.
†
Further adjusted for pre-eclampsia, placenta praevia and abruptio placenta.
‡
Low birth weight also adjusted for gestational age.