Patterns of Labour Interventions and Associated Maternal Biopsychosocial Factors in Australia: a Path Analysis.

In Australia, nearly half of births involve labour interventions. Prior research in this area has relied on cross-sectional and administrative health data and has not considered biopsychosocial factors. The current study examined direct and indirect associations between biopsychosocial factors and labour interventions using 19 years of population-based prospective data. The study included singleton babies among primiparous women of the 1973-1978 cohort of the Australian Longitudinal Study on Women's Health. Data from 5459 women who started labour were analysed using path analysis. 42.2% of babies were born without intervention (episiotomy, instrumental, or caesarean delivery): Thirty-seven percent reported vaginal birth with episiotomy and instrumental birth interventions, 18% reported an unplanned caesarean section without episiotomy and/or instrumental interventions, and 3% reported unplanned caesarean section after episiotomy and/or instrumental interventions. Vaginal births with episiotomy and/or instrumental interventions were more likely among women with chronic hypertension (RRR(95%-CI):1.50(1.12-2.01)), a perceived length of labour of more than 36 h (RRR(95%-CI):1.86(1.45-2.39)), private health insurance (RRR(95%-CI):1.61(1.41-1.85)) and induced labour (RRR(95%-CI):1.69(1.46-1.94)). Risk factors of unplanned caesarean section without episiotomy and/or instrumental birth intervention included being overweight (RRR(95%-CI):1.30(1.07-1.58)) or obese prepregnancy (RRR(95%-CI):1.63(1.28-2.08)), aged ≥ 35 years (RRR(95%-CI):1.87(1.46-2.41)), having short stature (< 154 cm) (RRR(95%-CI):1.68(1.16-2.42)), a perceived length of labour of more than 36 h (RRR(95%-CI):3.26(2.50-4.24)), private health insurance (RRR(95%-CI):1.38(1.17-1.64)), and induced labour (RRR(95%-CI):2.56(2.16-3.05)). Prevention and management of hypertension, diabetes, and obesity during preconception and/or antenatal care are keys for reducing labour interventions and strengthening the evidence-base around delivery of best practice obstetric care.