Maternal and neonatal outcomes among spontaneous vaginal births occurring in or out of water following intrapartum water immersion: The POOL cohort study.

ABSTRACT

OBJECTIVE: Warm water immersion during labour provides women with analgesia and comfort. This cohort study aimed to establish among women using intrapartum water immersion analgesia, without antenatal or intrapartum risk factors, whether waterbirth is as safe for them and their babies as leaving the water before birth. DESIGN: Cohort study with non-inferiority design. SETTING: Twenty-six UK NHS maternity services. SAMPLE A total of 73 229 women without antenatal or intrapartum risk factors, using intrapartum water immersion, between 1 January 2015 and 30 June 2022. The analysis excluded 12 827 (17.5%) women who received obstetric or anaesthetic interventions before birth. METHODS: Non-inferiority analysis of retrospective and prospective data captured in NHS maternity and neonatal information systems. MAIN OUTCOME MEASURES: Maternal primary outcome: obstetric anal sphincter injury (OASI) by parity; neonatal composite primary outcome: fetal or neonatal death, neonatal unit admission with respiratory support or administration of antibiotics within 48 hours of birth. RESULTS: Rates of the primary outcomes were no higher among waterbirths compared with births out of water rates of OASI among nulliparous women (waterbirth 730/15 176 [4.8%] versus births out of water 641/12 210 [5.3%]; adjusted odds ratio [aOR] 0.97, one-sided 95% CI, -∞ to 1.08); rates of OASI among parous women (waterbirth 269/24 451 [1.1%] versus births out of water 144/8565 [1.7%]; aOR 0.64, one-sided 95% CI -∞ to 0.78) and rates of the composite adverse outcome among babies (waterbirth 263/9868 [2.7%] versus births out of water 224/5078 [4.4%]; aOR 0.65, one-sided 95% CI -∞ to 0.79). CONCLUSION: Among women using water immersion during labour, remaining in the pool and giving birth in water was not associated with an increase in the incidence of adverse primary maternal or neonatal outcomes.