I love the smell of data in the morning, and none moreso than new data on UK waterbirths! This comes courtesy of the National Maternity and Perinatal Audit – who have conducted a retrospective study on births taking place in England in 2015-16.
Waterbirth: a national retrospective cohort study of factors associated with its use among women in England,
H. Aughey, J. Jardine, N. Moitt, K. Fearon, J. Hawdon, D. Pasupathy, I. Urganci, NMPA Project Team & T. Harris
This study uses the data recorded electronically during maternity care in England in 2015–16 to look at waterbirths. It describes 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. Sadly, data from anyone with a BMI over 35 is excluded. But we can still learn something from the data that is included.
So, What Does The New Data On UK Waterbirths Say?
Firstly, brace yourself for repeated use of the term ‘obese women’ to refer to people with a BMI 30-35. Sigh. I know it’s a category defined by the World Health Organisation, but it’s just such a loaded term. If you’re a researcher reading this and you want to know what term to use instead, I’d suggest “People with a BMI 30-35”. It’s accurate, it’s precise, it’s unequivocal, and while it’s imperfect, it doesn’t come with quite the same baggage.
They looked at the data for 46,088 births in 35 NHS Trusts in England. Of these 6264 (13.6%) were recorded as having occurred in water. 5379 people had BMIs 30-35.
But there were clear differences in the people accessing waterbirth, suggesting widespread inequality of access. You’re more likely to have a waterbirth if you’re white and aged 35–39. It was much less likely if you’re under 25, black or Asian, from an area of increased socioeconomic deprivation. It was also less likely if you have a higher BMI, which given how often we have to fight to gain access to water in labour didn’t come as much of a surprise.
In fact, I was slightly heartened to see that the adjusted odds ratio for BMI 30-35 was 0.77. This means that for every 100 people with a ‘normal’ BMI who birthed in water, 77 people with a BMI 30-35 did, which equates to about 10.5%.
What About The Risks?
Happily, the audit revealed no links between birthing in water and adverse outcomes.
They found no association between delivery in water and low Apgar score.
They found no association between waterbirth and obstetric anal sphincter injury (OASI).
There were positive correlations between waterbirth and reduced incidence of postpartum haemorrhage (PPH) and lower neonatal unit admission.
What Were The Conclusions?
That there was no association between waterbirth and the specific adverse maternal or neonatal outcomes. This study therefore adds to the body of evidence available to support decisions about giving birth in water. (Click here for the journal article I wrote for AIMS on High BMI waterbirth – time for trusts to take the plunge?)
While people with a BMI above 35 were excluded from this study, I was pleased to note the recommendation that there needs to be “further research to consider the safety and benefits of waterbirth for women with specific risk factors, such as those with an elevated BMI.”. Given that the NMPA is led by the Royal College of Obstetricians and Gynaecologists in partnership with the Royal College of Midwives, the Royal College of Paediatrics and Child Health and the London School of Hygiene and Tropical Medicine, this sounds like a call to action. I hope someone hears the call and answers.