There are many research studies demonstrating the benefits of water for labour and birth.
We have evidence from research involving thousands of women and babies that using water for labour and birth is safe and leads to good outcomes.
Using water also brings advantages for some women, including less need for other kinds of pain relief and increased maternal satisfaction.
But, as with many things in obstetrics, practice doesn’t always follow evidence.
The need for good evidence
Some organisations, such as the American College of Obstetricians and Gynecologists, do not recommend waterbirth. They sometimes cite anecdotal stories and hypothetical risks, while ignoring large studies which evidence that waterbirth is safe for women and babies.
This means that researchers need to keep doing more studies in order to demonstrate that woman-centred options are safe and effective. And those who want to support the use of water for labour and birth need to have access to good evidence.
This page contains details of the studies that I have come across and shared over the past decade or so. I add new ones all the time, so keep scrolling down to see the most recent data.
But let’s look at those studies, which come from around the world…
An open access study published in BMC Pregnancy and Childbirth by the Birthplace in England team showed that, for women having their first babies, getting into water while in labour helps in all kinds of ways and across all settings.
Analysis of data from 16,577 women showed that water immersion reduced the transfer rate for women who planned to birth at home or in freestanding or alongside midwifery units.
Furthermore, the data collected from the women who planned to give birth in freestanding midwifery units showed that using water during labour also reduced the caesarean section rate and increased their chance of having a straightforward normal birth.
Some groups of women were more likely to use water than others, though.
The results showed that, although immersion in water for pain relief was popular, women under 25, women who were not fluent in understanding English, women living in more deprived areas and women who were single or unsupported by their partner were less likely to use water in labour.
“Overall, 95.6% of women using a birthing pool had a spontaneous vertex delivery, 63.9% of which occurred in water. Half of nulliparas and three quarters of multiparas delivered in water. Adverse maternal and neonatal outcomes were rare. There were two cases of umbilical cord snap with waterbirth.
Compared with controls, significantly more women who used a birthing pool adopted an upright birth position, had hands off delivery technique, and a physiological third stage. Significantly fewer nulliparas had an episiotomy, and more had a second degree perineal tear, with no evidence of a difference for extensive perineal tears.” (Henderson et al 2014:1)
A Swedish comparative study by Ulfsdottir et al (2017), found that women giving birth in water had a lower risk of second-degree perineal tears, shorter labours and significantly less interventions (including artificial rupture of membranes, internal CTG and augmentation with synthetic oxytocin).
There were no differences in Apgar scores or admissions to neonatal intensive care unit and the women reported a more positive birth experience.
Three of the babies in the waterbirth group were noted to have cord avulsion and, while none of them were admitted to special care or suffered any complications as a result, the study authors remind midwives to watch out for this problem, which can easily be solved by clamping the cord.
Then we have The Waterbirth Project: São Bernardo Hospital experience (Camargo et al 2018). This quantitative observational study analysed the maternal and neonatal outcomes of 90 pregnant women who gave birth in water at São Bernardo Hospital in Portugal. In this study, being in water also reduced the time that the women were in labour.
Nearly a third of the women did not have vaginal examination and 57.8% either had no tears or just a first degree tear. The authors noted that the babies’ Apgar and Aqua Apgar (a specially modified Apgar score designed to be used for waterbirth) scores were excellent.
As Camargo et al (2018) conclude, “These safety outcomes, based on sound scientific evidence, should increasingly support and inform clinical decisions and increase the number of waterbirths in health facilities. The results of this study align with growing evidence that suggests waterbirth is a safe delivery option and therefore should be offered to women.”
In “Getting into the water: a prospective observational study of water immersion for labour and birth at a New Zealand District Health Board”, researchers “aimed to describe the maternal characteristics, intrapartum events, interventions, and maternal and neonatal outcomes of women who used water immersion during labour and birth at one New Zealand District Health Board (DHB).”
This study, like some others that have been carried out in different countries, particularly highlights the positive benefits of water in a hospital setting.
“The data revealed 84% of women who used water immersion for labour and birth across all three birth settings in this DHB had a spontaneous vaginal birth (Nulliparous 74.3%, Multiparous 95.7%).” The authors note that, “The New Zealand national average for spontaneous vaginal birth was reported to be 65.2% in 2014.”
“Water immersion for labour and birth is a positive intervention that benefits well women with uncomplicated pregnancies. This study shows that water immersion for labour and birth in a midwife-led unit with a community-based lead maternity care midwife results in excellent outcomes for women and infants. Water immersion for labour and birth also provides an essential option for women who have a desire to have a spontaneous vaginal birth.” (Maude & Kim 2020).
Expert researchers at Oxford Brookes University (Burns et al 2020) brought together research on childbirth, birth setting and the use of water immersion in labour and shared key points which highlighted the safety and benefits of the use of water for labour and birth, during and beyond the coronavirus pandemic.
Their points included that:
- Water immersion for healthy women is associated with a number of beneficial maternal outcomes with no known adverse risks to the neonate.
- COVID-19 is not a waterborne virus, therefore, the water environment dilutes respiratory droplet and faecal contamination potential.
- In the Coronavirus context, water immersion presents a lower risk of contamination risk for midwives compared with bed birth because it promotes the use of social distancing without interrupting normal midwifery care. Burns et al (2020)
The authors also noted that:
“The birthing pool environment presents a natural barrier between the woman and her midwife.
Supporting women in the water reduces droplet, aerosol and faecal contamination, presenting a low-risk transmission activity for the Coronavirus.
Water immersion for healthy women is associated with a number of beneficial maternal outcomes with no known adverse risks to the neonate.
For primiparous women, birthing in midwifery-led settings (AMU/FMU or home) water immersion reduces transfer rate with the greatest benefit seen at FMU.
Water immersion for labour and/or birth should be supported and encouraged as an effective method of analgesia.”
Burns E, Feeley C, Venderlaan J et al (2020). Coronavirus COVID-19: Supporting healthy pregnant women to safely give birth. Oxford: Oxford Brookes University.
This was a prospective observational study of 2077 low-risk pregnant women.
Some stayed on land the whole time, some laboured in water and got out to give birth and some laboured and birthed in water.
Again, this study showed that waterbirth is safe for babies. “In this cohort of low-risk pregnant women, births in water and on land were associated with similar rates of admission to the NICU.” (Lanier et al 2021).
A 2021 study looked at waterbirth safety and access. It was called “Waterbirth: a national retrospective cohort study of factors associated with its use among women in England.”
We know that the use of water for labour is very safe and beneficial. This research was undertaken because we don’t know quite so much about the outcomes and characteristics of the women who actually give birth in water.
So a retrospective (backwards-looking) cohort study was undertaken “to describe the proportion of births recorded as having occurred in water, the characteristics of women who experienced waterbirth and the odds of key maternal and neonatal complications associated with giving birth in water.” (Aughey et al 2021).
The authors looked at data from “46,088 low and intermediate risk singleton term spontaneous vaginal births in 35 NHS Trusts in England.” (Aughey et al 2021).
They found that waterbirth was more likely in older women up to the age of 40, and less common in women under 25, those of higher parity (by which we mean those who have had more babies already), or women with a higher than average BMI.
Waterbirth was also less likely in Black and Asian women and in those from areas of increased socioeconomic deprivation.
The study again evidences that waterbirth is safe. There was no association between waterbirth and specific adverse outcomes for either the mother or the baby.
But the fact that white women from higher socioeconomic backgrounds were more likely to be recorded as giving birth in water is of concern, and the researchers conclude that “Maternity services should focus on ensuring equitable access to waterbirth.” (Aughey et al 2021).
Bovbjerg et al (2021) carried out a large analysis of waterbirths. They looked at data from more than 17,500 water births and compared these with more than 17,500 births on land.
They found that:
“Waterbirth was associated with improved or no difference in outcomes for most measures, including neonatal death (adjusted odds ratio [aOR] 0.56, 95% CI 0.31–1.0), and maternal or neonatal hospitalisation in the first 6 weeks (aOR 0.87, 95% CI 0.81–0.92 and aOR 0.95, 95% CI 0.90–0.99, respectively). Increased morbidity in the waterbirth group was observed for two outcomes only: uterine infection (aOR 1.25, 95% CI 1.05–1.48) (but not hospitalisation for infection) and umbilical cord avulsion (aOR 1.57, 95% CI 1.37–1.82).”
Some helpful figures include that:
For every 5000 women who birth in water:
- 3 will develop a uterine infection (but none in the research required hospitalisation).
- There are 30 fewer postpartum haemorrhages than among the same number of women who birth on land.
- There will be 4 fewer severe perineal lacerations (deep tears) than among the same number of women who birth on land.
- There will be 14 fewer hospital admissions in the first six weeks after birth than among the same number of women who birth on land.
- 10 will have an umbilical cord avulsion (where the cord snaps before being tied).
For every 5000 babies who are born in water:
- There are 6 fewer cases of respiratory distress syndrome than among the same number of babies who are born on land.
- There are 10 fewer hospital admissions in the first six weeks after birth than among the same number of babies who are born on land.
“Importantly, there was no difference in the number of neonatal deaths between babies born underwater and those born on land.” (Bovbjerg et al 2021).
Australia: is a trial feasible?
In 2022, researchers in Australia looked at the question of whether a prospective study of water birth is feasible. This question has been debated for years. Randomised trials are considered to be the best way of assessing the effectiveness of an intervention, but the idea of randomising women in labour is problematic for a number of reasons.
“We conducted a prospective cohort study at an Australian maternity hospital. Eligible women with uncomplicated pregnancies at 36 weeks of gestation were recruited and surveyed about their willingness for randomization.”
“1260 participants were recruited; 15% (n = 188) agreed to randomization in a future trial. 550 women were analyzed by intention-to-treat analysis: 351 (waterbirth) and 199 (nonwaterbirth).”
“A randomized trial of waterbirth compared with nonwaterbirth, powered to detect a difference in serious neonatal morbidity, is unlikely to be feasible. A powered prospective study with intention-to-treat analysis at onset of second stage is feasible.”