Neonatal and maternal morbidity in relation to the length of the second stage of labour

OBJECTIVE: To investigate the relation between the duration of the second stage of labour and subsequent early neonatal and maternal morbidity. DESIGN: Retrospective analysis of a regional obstetric database. SETTING: 17 maternity units in the North West Thames Health Region. SUBJECTS: Selected from 36,727 consecutive singleton deliveries in 1988. The analysis was confined to the 25,069 women delivered of an infant of at least 37 weeks gestation with a cephalic presentation following the spontaneous onset of labour. MAIN OUTCOME MEASURES: The relative risk of early maternal morbidity, postpartum haemorrhage (PPH) and postpartum infection, and neonatal morbidity, as judged by low Apgar scores or admission to the special care baby unit (SCBU), in relation to anthropomorphic characteristics (parity and birthweight), interventions (epidural analgesia, episiotomy and operative delivery), signs of fetal compromise (meconium staining of the amniotic fluid or abnormal cardiotocography (CTG)), maternal morbidity in labour (pyrexia) and the duration of the second stage of labour. RESULTS: The duration of the second stage of labour had a significant independent association with the risk of both PPH and maternal infection after adjustment for other factors. However, there was a similar or greater risk of PPH in association with operative delivery or a birthweight greater than 4000 g. Both maternal pyrexia in labour and primiparity were associated with a greater risk of post partum maternal infection than was the duration of the second stage, although all these factors were statistically significant. In contrast, the duration of the second stage was not significantly associated with the risk of a low Apgar score or admission to SCBU after adjustment for other factors. CONCLUSIONS: The duration of the second stage of labour has a positive independent association with early maternal morbidity. We could show no such relation between time spent in the second stage of labour and the frequency of low Apgar scores or the rate of admission to SCBU. With current management approaches, in the absence of factors suggesting fetal compromise, second stage labours of up to 3 h duration do not seem to carry undue risk to the fetus.