First-birth pregnancy characteristics of the two cohorts of women with linked first and second births
| Characteristics at time of first birth | 1994–1997 First births Cohort 1 N=82988 (%) | 2001–2004 First births Cohort 2 N=85859 (%) |
|---|---|---|
| Maternal age | ||
| Age <20 years | 9.5 | 8.1 |
| Age 20–34 years | 85.5 | 83.9 |
| Age ≥35 years | 5.1 | 8.0 |
| Nulliparous* | 40.1 | 42.0 |
| Born outside Australia | 23.6 | 24.0 |
| Type of care | ||
| Public patient | 62.2 | 60.4 |
| Private patient/public hospital | 17.9 | 9.5 |
| Private patient/private hospital | 20.0 | 30.1 |
| Multifetal pregnancies (twins, etc) | 0.6 | 0.8 |
| Breech presentation at term | 4.2 | 4.4 |
| Labour induction | 23.3 | 28.7 |
| Gestational age at birth | ||
| <37 weeks | 6.1 | 6.3 |
| 37–41 weeks | 90.4 | 90.7 |
| ≥42 weeks | 3.5 | 3.0 |
| All caesarean deliveries | 17.7 | 26.1 |
| For term breech presentation† | 84.7 | 97.5 |
| For multifetal pregnancy† | 43.7 | 62.9 |
| Following labour induction† | 19.7 | 27.8 |
*As percentage of all pregnancies in the period.
†Denominators are first-births with the specified characteristics (ie, breech, multifetalpregnancy and labour inductions, respectively).