Main results
Our study found that babies born to women who utilised the birthing pool for WWI or waterbirth, despite some moderate risk factors, had lower rates of admission to the NNU and lower rates of observation for a suspected infectious condition and antibiotic administration. Encouragingly, this adds to existing evidence that WWI/Waterbirth is not associated with increased rates of NNU admission in low-risk women(6, 8). No babies required NNU admission for water inhalation or drowning.
The risk of neonatal sepsis is often cited by those who oppose WWI/Waterbirth (15). However, case reports of neonates infected with L. pneumophila and P. aeruginosa(16), appear to have resulted from a deviation from established waterbirth protocols and the use of unclean water. Overwhelmingly, recent literature suggests no increase in infective sequalae from WWI/WB, which is consistent with our findings(17, 18).
Most women (95.5%) who were febrile intrapartum had an epidural, likely explaining the favourable results for the WWI/WB group. This association between maternal pyrexia and epidurals is well established with one retrospective study of 261,457 women finding those with an epidural five times more likely to experience pyrexia and neonates 1.6 times more likely to receive antibiotics (19). The multivariate regression analysis removed women with epidurals from the cohort and subsequently showed no differences in NNU admission between the groups.
The role of waterbirth as a contributor to rates of perineal trauma is controversial. Our study showed similar rates of OASIS between land birth and WWI/WB. However, the subgroup analysis comparing spontaneous vaginal birth in women on land and in water, showed a significant association between land birth and increased rates of episiotomy. This land birth group did not include women who used WWI during labour and then birthed on land. A Cochrane review (6), and several recent studies (20), support the notion that WWI/WB does not increase rates of perineal trauma and our findings are consistent with this.
Our study suggested lower rates of PPH in the WWI/Waterbirth group, however estimating blood loss is notoriously inaccurate(21), and more challenging in water. The waterbirth protocol within the study site recommends placental delivery occurs on land, thereby allowing blood loss to be more accurately estimated. The authors recognise that ‘pool exit’ is not always immediate and hence estimations of blood loss in the waterbirth group are more likely to be imprecise. Neiman (18) suggests a small increase in PPH with waterbirth, but this is inconsistent with the broader literature (6, 20, 22), which concur no clinical difference between groups.
Cord avulsion occurs when rapid cord traction overstretches umbilical cords that cannot reach above the water surface (23). This is a rare event and studies are inevitably underpowered to prove a statistically significant association with waterbirth. According to Schafer (23), based on pooled data of 10,000 waterbirths, the incidence of cord avulsion appears increased at approximately 3.10 per 1000. However, this risk can be mitigated by clear waterbirth protocols, midwifery education and discussion with women before pool entry (20, 23).