Plain English Summary
Background and study aims
It is estimated that up to 60,000 (9 in every 100) babies are born into water annually in the UK and with encouragement from NICE for maternity units to provide birthing pools for women, this number may increase further. Women use a birth pool during labour for pain relief, and some women choose to remain in the pool for the birth of their baby. Over the years there have been reports of babies that had breathing difficulties or infection following birth in water, and there is a concern that women that have a waterbirth more often sustain severe trauma to their vaginal area or have unrecognised heavy bleeding. Despite concern and some reports in the press, to date there have not been studies large enough to show whether or not waterbirth causes an increase in these poor outcomes for mothers or their babies. The aim of this study is to find out whether waterbirth is as safe for mothers and babies as leaving the pool before birth.
Who can participate?
Women who meet NICE criteria for ‘low risk’ and who use a pool (water immersion) during labour
What does the study involve?
The study collects data on the births of all women in around 30 maternity units during 2015-2020 to see how many women are using birth pools, how many women give birth in water and whether mothers or their babies come to any extra harm as a result of waterbirth. The study includes women giving birth to their first baby and women giving birth to a subsequent child. The study needs to collect information on 15,000 waterbirths and 15,000 births out of water. To do this without disturbing women in labour or just after birth, when they are looking after their new baby, the study uses information collected as part of each woman’s and linked baby’s maternity record stored at hospitals in computerised systems. For babies who need specialist care after birth, the study also uses data held by the National Neonatal Research Database. Some of the data needed for this study is already collected by maternity units, so data from births from 2015 onwards can be included in the study. However, as some important information needed to fully answer the study questions, such as how many babies have antibiotics, and how many women deliver the placenta underwater, is currently not collected, some new items are added to maternity computer systems when the study starts in 2018. To keep women’s information confidential, the data stored in existing maternity information systems has the identifying information, such as names, addresses and NHS numbers, removed before the information is sent to the research team in Cardiff for analysis.
What are the possible benefits and risks of participating?
The study will produce academic papers and evidence based information for women and their partners on waterbirth. The study findings will be of great interest and are expected to generate much press interest, and quickly influence the information provided to pregnant women throughout the UK. The benefit of participating is minimal to the individual, but will be making a contribution to research. The main advantage is that the participant will be able to share experiences to help improve understanding of the factors that influence the use of birth pools and giving birth in water. This study has been identified as low risk, and no higher than the risk of standard medical care. Participation in the discussion group is not likely to involve any particular risks although it may bring back memories of difficult or distressing experiences. The main disadvantage for the participant is giving up their time to join in the discussion.
Where is the study run from?
University Hospital Wales (UK)
When is the study starting and how long is it expected to run for?
April 2018 to August 2021
Who is funding the study?
NIHR Health Technology Assessment Programme (UK)
Who is the main contact?
Establishing the safety of waterbirth for mothers and babies: a cohort study with nested qualitative component
To establish whether for ‘low-risk’ women who use a pool during labour, waterbirth, compared to leaving a pool prior to birth, is as safe for mothers and babies.
Not provided at time of registration
Cohort study with a nested qualitative component, using a combination of data captured retrospectively and prospectively (January 2015 to November 2020) in electronic NHS maternity and neonatal information systems
Primary study design
Secondary study design
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
A natural experiment using a cohort design with a nested qualitative component will answer the study objectives by using a combination of data captured retrospectively and prospectively in electronic NHS maternity and neonatal information systems. The qualitative component will explore factors associated with high and low rates of pool use; data will be gathered in online discussion groups, focus groups and one-to-one interviews with key stakeholders, including women.
To answer all research objectives approximately 600,000 individual computerised maternity records held on secure NHS servers at around 30 NHS sites, covering the period January 2015 – November 2020 will be accessed. To provide necessary denominator data, and to be able to compare characteristics of pool users and non-pool users, a minimal data set will be extracted relating to women who did not use a pool in labour, whilst a more extensive dataset will be extracted for women who did use a pool in labour. An important clinical question is whether there is a differential effect of waterbirth on severe perineal trauma (OASIS) amongst nulliparous and parous women. To undertake this subgroup analysis will require a necessarily large sample (30,000). As data relating to perineal trauma and waterbirth are already captured, and to avoid unnecessarily prolongation of the study, this analysis will use a combination of retrospective and prospectively collected data, including births from 2015 to 2020.
The sample required for the neonatal primary outcome is smaller (16,200) and, as all essential data are not currently collected for one component of this composite outcome (antibiotic administration within 48 hours of birth on postnatal wards) additional data fields will to be added to maternity systems at participating NHS sites. Therefore, we will collect these data on births prospectively during the period June 2018 to November 2020.
Some neonatal outcomes of interest, including neonatal hypoxia, respiratory support or neonatal mortality, are already held by study sites or by the National Neonatal Research Database (NNRD). Where available and where the risk status, and pool usage of mothers can be determined, retrospective data will be utilised to increase the power of the analysis around secondary neonatal outcomes.
The NNRD holds individual patient level data on all babies admitted for National Health Service (NHS) neonatal care in England, Scotland and Wales from 2014 to present. To obtain detailed treatment and outcome information on any baby who required admission to a neonatal unit, following their mother’s pool use in labour, the identifiers of all babies born to women who used a pool during the period of prospective data collection will be extracted and matched to any records held by the NNRD.
The primary study aim is to compare maternal and neonatal outcomes for ‘low risk’ women who gave birth in water against ‘low risk’ women who left the water prior to birth.
Primary outcome measure
Maternal primary outcome measure:
Obstetric Anal Sphincter Injuries (OASIS), measured using routinely collected maternal data (EUROKING) at birth
Neonatal primary outcome measure:
Composite outcome of ‘adverse neonatal outcomes or treatment:
1. Any neonatal unit admission requiring respiratory support, measured using routinely collected neonatal data (NNRD) at hospital discharge
2. Antibiotic administration within 48 hours of birth (with or without culture proven infection), measured using routinely collected maternal data (EUROKING) at hospital discharge
3. Intrapartum stillbirth or neonatal death, measured using routinely collected maternal data (EUROKING) at hospital discharge
Secondary outcome measures
Maternal secondary outcome measures:
1. Maternal intrapartum: Shoulder dystocia and required management, management of the third stage of labour, need and reason for obstetric involvement in woman’s care including sepsis; mode of birth, maternal position at birth, treatment for haemorrhage, incidence and management of perineal and other genital trauma. Measured using routinely collected maternal data (EUROKING) at birth
2. Maternal postnatal: duration of postnatal stay, breastfeeding initiation and continuation, higher level care, and maternal readmission to hospital within 7 days of birth. Measured using routinely collected maternal data (EUROKING) at hospital discharge
Infant secondary outcome measures:
1. Snapped umbilical cord prior to clamping, skin to skin contact at birth, timing of cord clamping, resuscitation , Apgar scores. Measured using routinely collected maternal data (EUROKING) at birth
2. Administration and duration of intravenous antibiotics, measured using routinely collected maternal data (EUROKING) at hospital discharge
3. Lumbar puncture, culture proven infection, brachial plexus injury, treatment for jaundice, therapeutic hypothermia, measured using routinely collected maternal data (EUROKING) at hospital discharge
4. Neonatal unit admission and duration, cause of neonatal death, respiratory support, measured using routinely collected neonatal and maternal data (NNRD, EUROKING) at hospital discharge
5. Readmission to hospital within 7 days of birth, measured using routinely collected maternal data (EUROKING) at readmission
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Routine Data Work Package: Women who meet NICE criteria for ‘low risk’ and who use a pool (water immersion) during labour
Qualitative Work Package: [online stakeholder discussion groups]
1. Heads of Midwifery / Midwifery Managers from study sites
2. Consultant Midwives from study sites
3. Band 5/6 clinically focused midwives
4. UK Obstetricians from within and outside of study sites (accessed via RCOG or another route)
5. UK Neonatologists from within and outside of study sites (accessed via the UK Neonatal Collaborative (UKNC) the RCPCH or another route
6. Public including members of the RCOG Women’s group, with participation open to women at study and non-study sites
Target number of participants
600,000 computerised maternity records. Routine Data Work Package: 30,000 mothers. 16,200 neonates. Qualitative Work Package: Six closed online stakeholder discussion groups will be conducted, including the following participants: 1. Heads of Midwifery / Midwifery Managers from study sites. 2. Consultant Midwives from study sites. 3. Band 5/6 clinically focused midwives. 4. UK Obstetricians from within and outside of study sites (accessed via RCOG or another route). 5. UK Neonatologists from within and outside of study sites (accessed via the UK Neonatal Collaborative (UKNC) the RCPCH or another route. 6. Public including members of the RCOG Women’s group, with participation open to women at study and non-study sites.
Participant exclusion criteria
Excluded from data analysis: Data relating to women and babies recorded in EuroKing as being ‘Born Before Arrival’ (BBA), or recorded as intentionally born without midwifery attendance, will be excluded from primary analysis as well as those who opt-out from the study
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
University Hospital Wales
Health Technology Assessment Programme
NIHR Health Technology Assessment Programme, HTA
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Planned publication in a high-impact peer reviewed journal.
IPD sharing statement
The datasets generated during and/or analysed during the current study are/will be available upon request from Michael Robling (RoblingMR@cardiff.ac.uk).
Intention to publish date
Participant level data
Available on request
Basic results (scientific)