Table 3.
Clinical characteristics and obstetric interventions among primiparous women with OASIS and women without OASIS. Data are presented in frequencies (and numbers). p Values from χ2 test
| 2003–2005 |
2008–2010 |
|||
|---|---|---|---|---|
| Primiparous women | OASIS | Non-OASIS | OASIS | Non-OASIS |
| Deliveries | n=489 | n=7562 | n=263 | n=8574 |
| Incidence OASIS | 6.1 (489/7562) | 3 (263/8574) | ||
| Risk factors (%) | ||||
| Age (years) | p=0.08 | p=0.39 | ||
| 15–29 | 43.4 (n=212) | 48.6 (n=3673) | 40.7 (n=107) | 43.9 (n=3765) |
| 30–34 | 43.4 (n=212) | 39 (n=2952) | 44.9 (n=118) | 40.7 (n=3486) |
| 35–51 | 13.3 (n=65) | 12.4 (n=937) | 14.4 (n=38) | 15.4 (n=1323) |
| Birthweight (g) | p<0.001 | p<0.001 | ||
| 720–2999 | 8 (n=39) | 17 (n=1282) | 8.7 (n=23) | 16.6 (n=1423) |
| 3000–3499 | 27.6 (n=135) | 38.5 (n=2915) | 34.2 (n=90) | 39.4 (n=3380) |
| 3500–3999 | 39.3 (n=192) | 32.8 (n=2478) | 38.4 (n=101) | 33.6 (n=2882) |
| 4000–4499 | 20.2 (n=99) | 10.4 (n=786) | 14.8 (n=39) | 9.1 (n=782) |
| 4500–5850 | 4.9 (n=24) | 1.3 (n=101) | 3.8 (n=10) | 1.2 (n=107) |
| Delivery method | p<0.001 | p<0.001 | ||
| Spontaneous | 65 (n=318) | 82.5 (n=6240) | 64.6 (n=170) | 78.7 (n=6748) |
| Ventouse | 29.4 (n=144) | 15.7 (n=1187) | 34.2 (n=90) | 20 (n=1712) |
| Forceps | 5.5 (n=27) | 1.8 (n=135) | 1.1 (n=3) | 1.3 (n=114) |
| Episiotomy, all vaginal deliveries | p=0.21 | p=0.93 | ||
| 33.9 (n=166) | 31.2 (n=2362) | 36.5 (n=96) | 36.2 (n=3107) | |
| Episiotomy, spontaneous deliveries | p=0.07 | p=0.40 | ||
| 20.4 (n=65) | 24.9 (n=1555) | 20 (n=34) | 22.7 (n=1535) | |
| Episiotomy, instrumental deliveries | p<0.001 | p<0.001 | ||
| 59.1 (n=101) | 61 (n=807) | 66.7 (n=62) | 86.1 (n=1572) | |
| Duration second stage (min) | p<0.001 | p=0.07 | ||
| 0–09 | 2.7 (n=13) | 3.5 (n=268) | 3.4 (n=9) | 3.1 (n=264) |
| 10–29 | 20.2 (n=99) | 31.2 (n=2356) | 28.1 (n=74) | 29.4 (n=2517) |
| 30–59 | 36.8 (n=180) | 41.1 (n=3110) | 35.4 (n=93) | 41.8 (n=3580) |
| 60–205 | 39.5 (n=193) | 23.8 (n=1801) | 33.1 (n=87) | 25.7 (n=2201) |
| Missing data (n=4/n=27) | 0.8 (n=4) | 0.4 (n=27) | 0 (n=0) | 0.1 (n=12) |
| Epidural | p=0.14 | p=0.90 | ||
| 46.6 (n=228) | 43.2 (n=3266) | 48.7 (n=128) | 48.3 (n=4139) | |
| Shoulder dystocia | p<0.001 | p<0.001 | ||
| 2.5 (n=12) | 0.8 (n=64) | 3.4 (n=9) | 0.6 (n=55) | |
| Occiput posterior presentation | p=0.003 | p<0.001 | ||
| 4.1 (n=20) | 2.1 (n=156) | 6.5 (n=17) | 2.7 (n=228) | |
| Induced labour | p=0.32 | p=0.89 | ||
| 15.3 (n=75) | 17.1 (n=1290) | 19 (n=50) | 18.7 (n=18.7) | |
OASIS, obstetric anal sphincter injuries.