Background
Methods
Population
Data sources and variables
Analyses
Association of first and second birth factors with OASI recurrence
Association of first birth and second pregnancy factors with planned caesarean section for subsequent birth
Ethics approval
Results
Association of first and second birth factors with OASI recurrence
OASI at 2nd birth | No OASI at 2nd birth | p | Cr ORs | Adj ORs with all risk factors in model | |||
---|---|---|---|---|---|---|---|
n = 276 | n = 4532 | ||||||
(5.7%) | (94.3%) | ||||||
Country of birth*
| Asian | 47 (17.0) | 910 (20.2) | 0.23 | 0.82 [0.60, 1.13] | 0.89 (0.63, 1.26) | |
Non Asian | 226 (81.9) | 3594 (79.3) | Reference | Reference | |||
FIRST BIRTH FACTORS
| |||||||
Diabetes
| Yes | 17 (6.2) | 174 (3.8) | 0.06 | 1.64 [0.98, 2.75] | 1.76 [1.03, 3.01] | |
No | 259 (39.8) | 4358 (96.2) | Reference | Reference | |||
Epidural/spinal/general
| Yes | 109 (39.5) | 1993 (44.0) | 0.14 | 0.82 [0.64, 1.05] | 0.79 [0.59, 1.06] | |
No | 167 (60.5) | 2539 (56.0) | Reference | Reference | |||
Birth mode
| Instrumental | 120 (43.5) | 2007 (44.3) | 0.79 | 0.97 (0.76, 1.24) | 1.04 [0.78, 1.40] | |
Non Instrumental | 156 (56.5) | 2525 (55.7) | Reference | Reference | |||
Episiotomy
| Yes | 121 (43.8) | 1939 (42.8) | 0.73 | 1.04 [0.82, 1.33] | 1.13 [0.86, 1.50] | |
No | 155 (56.2) | 2593 (57.2) | Reference | Reference | |||
Birthweight(kg)
| <3.0 | 29 (10.5) | 462 (10.2) | 0.34 | 1.08 [0.70, 1.66] | 1.40 [0.89, 2.19] | |
3.0 - <3.5 | 95 (34.4) | 1636 (36.1) | Reference | Reference | |||
3.5 - <4.0 | 119 (43.1) | 1749 (38.6) | 1.17 [0.89, 1.55] | 0.94 [0.70, 1.27] | |||
≥ 4.0 | 33 (12.0) | 685 (15.1) | 0.83 [0.55, 1.25] | 0.53 [0.34, 0.82] | |||
Inter pregnancy interval (years)*
| <1 | 50 (18.1) | 1020 (22.5) | 0.39 | 0.76 [0.52, 1.13] | 0.78 [0.52, 1.17) | |
1- < 2 | 126 (45.7) | 1926 (42.5) | 1.02 [0.74, 1.40] | 1.04 [0.75, 1.45) | |||
2- < 3 | 59 (21.4) | 919 (20.3) | Reference | Reference | |||
≥3 | 41 (14.9) | 666 (14.7) | 0.96 [0.64, 1.45] | 1.01 [0.66, 1.54] | |||
SECOND BIRTH FACTORS
| |||||||
Mat age
| <25 | 29 (10.5) | 550 (12.1) | 0.61 | 0.87 [0.58, 1.30] | 0.93 [0.61, 1.41] | |
25-34 | 189 (68.5) | 3110 (68.6) | Reference | Reference | |||
≥35 | 58 (21.0) | 872 (19.2) | 1.09 [0.81, 1.48] | 1.07 [0.78, 1.46] | |||
Hypertension
| Yes | 16 (5.8) | 161 (3.5) | 0.05 | 1.67 [0.99, 2.84] | 1.56 [0.90, 2.71] | |
No | 260 (94.2) | 4371 (96.5) | Reference | Reference | |||
Gestation (weeks)*
| <37 | 4 (1.5) | 155 (3.4) | <0.01 | 0.36 [0.13, 0.99] | 0.73 [0.24, 2.19] | |
37-38 | 29 (10.5) | 840 (18.5) | 0.49 [0.33, 0.73] | 0.55 [0.36, 0.84] | |||
39-40 | 197 (71.4) | 2779 (61.3) | Reference | Reference | |||
≥41 | 46 (16.7) | 757 (16.7) | 0.86 [0.62, 1.19] | 0.72 [0.51, 1.02] | |||
Induction/Augmentation
| Yes | 143 (51.8) | 2428 (53.6) | 0.57 | 0.93 [0.73,1.19] | 0.95 [0.73, 1.24] | |
No | 133 (48.2) | 2104 (46.3) | Reference | Reference | |||
Epidural
| Yes | 48 (17.4) | 892 (19.7) | 0.35 | 0.86 [0.62, 1.18] | 0.95 [0.66, 1.38] | |
No | 228 (82.6) | 3640 (80.3) | Reference | Reference | |||
Birth mode
| Instrumental | 24 (8.7) | 289 (6.4) | 0.13 | 1.40 (0.91, 2.16) | 1.30 [0.80, 2.12] | |
Non-instrumental | 252 (91.3) | 4243 (93.6) | Reference | Reference | |||
Episiotomy
| Yes | 68 (24.6) | 1180 (26.0) | 0.61 | 0.93 [0.70, 1.23] | 0.84 [0.62, 1.14] | |
No | 208 (75.4) | 3352 (74.0) | Reference | Reference | |||
Infant sex*
| Male | 158 (57.3) | 2323 (51.3) | 0.05 | 1.27 [1.00, 1.63] | 1.12 [0.87, 1.44] | |
Female | 118 (42.7) | 2208 (48.7) | Reference | Reference | |||
Birthweight(kg)*
| <3.0 | 14 (5.1) | 543 (12.0) | <0.01 | 0.54 [0.30, 0.96] | 0.56 [0.23, 1.06] | |
3.0 - <3.5 | 80 (29.0) | 1675 (37.0) | Reference | Reference | |||
3.5 - <4.0 | 107 (38.8) | 1653 (36.5) | 1.36 [1.01, 1.83] | 1.48 [1.08, 2.02] | |||
≥4.0 | 75 (27.2) | 658 (14.5) | 2.39 [1.72, 3.31] | 2.89 [1.98, 4.22] | |||
Year of second birth
| 01-05 | 68 (24.6) | 1098 (24.2) | 0.24 | Reference | Reference | |
06-08 | 87 (31.5) | 1643 (36.3) | 0.86 [0.62, 1.19] | 0.84 [0.60, 1.17] | |||
09-11 | 121 (43.8) | 1791 (39.5) | 1.09 [0.80, 1.48] | 1.07 [0.78, 1.47] |
Association of first birth with planned caesarean section for subsequent birth
Planned CS | Planned vaginal | p | crOR | aOR | ||
---|---|---|---|---|---|---|
n = 1447 | n = 4933 | |||||
(22.7%) | (77.3%) | |||||
Country of birth*
| Asian | 202 (14.0) | 979 (19.9) | <0.01 | 0.66 (0.56, 0.77) | 0.69 (0.58, 0.84) |
Non Asian | 1236 (85.4) | 3923 (79.5) | Reference | |||
FIRST BIRTH FACTORS
| ||||||
Diabetes
| Yes | 70 (4.8) | 200 (4.1) | 0.19 | 1.20 (0.91, 1.59) | 1.17 (0.84, 1.63) |
No | 1377 (95.2) | 4733 (95.9) | Reference | |||
Hypertension
| Yes | 133 (9.2) | 430 (8.7) | 0.58 | 1.06 (0.86, 1.30) | 1.00 (0.79, 1.27) |
No | 1314 (90.8) | 4503 (91.3) | Reference | |||
Gestation* (weeks)
| <37 | 34 (2.4) | 84 (1.7) | <0.01 | 1.49 (0.99, 2.23) | 1.39 (0.87, 2.22) |
37-38 | 160 (11.1) | 621 (12.6) | 0.95 (0.78, 1.15) | 0.81 (0.65, 0.99) | ||
39-40 | 782 (54.0) | 2870 (58.2) | Reference | Reference | ||
≥41 | 471 (32.5) | 1357 (27.5) | 1.27 (1.12, 1.45) | 1.42 (1.22, 1.65) | ||
Induction/augmentation
| Yes | 1064 (73.5) | 3352 (68.0) | <0.01 | 1.31 (1.15, 1.49) | 1.11 (0.96, 1.30) |
No | 383 (26.5) | 1581 (32.0) | Reference | |||
Epidural/spinal or GA
| Yes | 915 (63.2) | 2185 (44.3) | <0.01 | 2.16 (1.92, 2.44) | 1.73 (1.50, 2.00) |
No | 532 (36.8) | 2748 (55.7) | Reference | |||
Birth mode
| Instrumental | 815 (56.3) | 2209 (44.8) | <0.01 | 1.59 (1.41, 1.79) | 1.16 (0.99, 1.35) |
Non-instr | 632 (43.7) | 2724 (55.2) | Reference | |||
Episiotomy
| Yes | 718 (49.6) | 2121 (43.0) | <0.01 | 1.31 (1.16, 1.47) | 1.12 (0.98, 1.29) |
No | 729 (50.4) | 2812 (57.0) | Reference | |||
OASIS
| Fourth | 267 (18.5) | 203 (4.1) | <0.01 | 5.27 (4.35, 6.70) | 4.95 (4.00, 6.13) |
Third/Unknown** | 1180 (81.5) | 4730 (95.9) | Reference | |||
Birthweight (kg)*
| <3.0 | 130 (9.0) | 504 (10.2) | <0.01 | 1.10 (0.88, 1.37) | 0.99 (0.77, 1.27) |
3.0- < 3.5 | 417 (28.8) | 1772 (35.9) | Reference | Reference | ||
3.5- < 4.0 | 562 (38.8) | 1918 (38.9) | 1.25 (1.08, 1.44) | 1.22 (1.04, 1.43) | ||
≥4.0 | 337 (23.3) | 739 (15.0) | 1.94 (1.64, 2.29) | 1.66 (1.38, 2.01) | ||
Interpregnancy interval
| <1 | 291 (20.1) | 1094 (22.2) | 0.04 | 0.91 (0.76, 1.09) | 0.95 (0.77, 1.17) |
(years)
| 1- < 2 | 601 (41.5) | 2099 (42.6) | 0.98 (0.84, 1.15) | 1.03 (0.86, 1.22) | |
2- < 3 | 292 (20.2) | 999 (20.3) | Reference | Reference | ||
≥3 | 263 (18.2) | 740 (15.0) | 1.22 (1.00, 1.47) | 1.13 (0.91, 1.40) | ||
SECOND PREGNANCY
| ||||||
Maternal age
| <25 | 136 (9.4) | 593 (12.0) | <0.01 | 0.80 (0.65, 0.97) | 0.75 (0.60, 0.93) |
25-34 | 972 (67.2) | 3381 (68.5) | Reference | Reference | ||
35-40 | 309 (21.4) | 897 (18.2) | 1.20 (1.03, 1.39) | 1.13 (0.96, 1.33) | ||
>40 | 30 (2.1) | 62 (1.3) | 1.68 (1.08, 2.62) | 1.42 (0.87, 2.31) | ||
Diabetes
| Yes | 93 (6.4) | 269 (5.5) | 0.16 | 1.19 (0.93, 1.52) | 0.99 (0.74, 1.33) |
No | 1354 (93.6) | 4664 (94.5 | Reference | |||
Hypertension
| Yes | 53 (3.7) | 187 (3.8) | 0.82 | 0.97 (0.71, 1.32) | 0.78 (0.55, 1.12) |
No | 1394 (96.3) | 4746 (96.2) | Reference | |||
Gestation* (weeks)
| <37 | 85 (5.9) | 168 (3.4) | <0.01 | 2.03 (1.55, 2.67) | 2.20 (1.64, 2.95) |
37-38 | 581 (4.02) | 888 (18.0) | 2.63 (2.31, 3.0) | 2.87 (2.49, 3.31) | ||
39-40 | 757 (52.3) | 3041 (61.7) | Reference | Reference | ||
≥41 | 24 (1.7) | 835 (16.9) | 0.12 (0.08, 0.18) | 0.11 (0.07, 0.16) | ||
Year of second birth
| 01-05 | 309 (21.4) | 1194 (24.2) | 0.03 | Reference | Reference |
06-08 | 515 (35.6) | 1774 (36.0) | 1.12 (0.96, 1.32) | 1.06 (0.89, 1.27) | ||
09-11 | 623 (43.0) | 1965 (39.8) | 1.22 (1.05, 1.43) | 1.19 (1.01, 1.42) |