The POOL study: establishing the safety of waterbirth for mothers and babies
| ISRCTN | ISRCTN13315580 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN13315580 |
| Secondary identifying numbers | HTA 16/149/01 |
- Submission date
- 18/04/2018
- Registration date
- 04/05/2018
- Last edited
- 16/01/2025
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Pregnancy and Childbirth
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. This study aims 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 26 maternity units during 2015-2022 (updated 09/09/2022, previously 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 water births 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 contributing 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 March 2024
Who is funding the study?
NIHR Health Technology Assessment Programme (UK)
Who is the main contact?
Rebecca Milton, miltonrl1@cardiff.ac.uk
Julia Sanders, sandersj3@cardiff.ac.uk
Contact information
Public
Room 418H, 4th Floor Neuadd Meirionydd
Cardiff University
Heath Park Site
Cardiff
CF14 4YS
United Kingdom
| Phone | +44 (0)29206 87612 |
|---|---|
| miltonrl1@cardiff.ac.uk |
Public
Study Manager
6th Floor Neuadd Meirionnydd
Heath Park
Cardiff
CF14 4YS
United Kingdom
 ORCID ID |
0000-0001-5759-0310 |
|---|---|
| Phone | +44 (0)2920 687174 |
| BarlowC2@cardiff.ac.uk |
Study information
| Study design | Cohort study with a nested qualitative component, using a combination of data captured retrospectively and prospectively (January 2015 to June 2022) in electronic NHS maternity and neonatal information systems |
|---|---|
| Primary study design | Observational |
| Secondary study design | Cohort study |
| Study setting(s) | Hospital |
| Study type | Other |
| Participant information sheet | Not available in web format, please use the contact details to request a patient information sheet |
| Scientific title | Establishing the safety of waterbirth for mothers and babies: a cohort study with nested qualitative component |
| Study acronym | POOL |
| Study hypothesis | 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. |
| Ethics approval(s) | Approved 09/10/2018, Wales Research Ethics Committee (Wales REC 3) (Castlebridge 4, 15 – 19 Cowbridge Road East, Health and Care Research Wales, CF11 9AB, United Kingdom; +44(0)2920 785739; wales.rec3@wales.nhs.uk), ref: 18/WA/0291 |
| Condition | Birth in water following water immersion during labour |
| Intervention | Current interventions as of 09/09/2022: Summary of methodology: 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 – June 2022 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 2022. 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 be added to maternity systems at participating NHS sites. Therefore, we will collect these data on births prospectively during the period from site opening (c. January 2019 onwards to 30th June 2022/site closure). 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 the 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 the water against ‘low risk’ women who left the water prior to birth. _____ Previous interventions: 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. |
| Intervention type | Other |
| 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 | Current secondary outcome measures as of 09/09/2022: 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, maternal position at birth, treatment for haemorrhage, incidence and management of perineal and other genital trauma. Measured using routinely collected maternity data (EUROKING) at birth. 2. Maternal postnatal: duration of postnatal stay, breastfeeding initiation and continuation, higher level care, and maternal readmission to the hospital within 7 days of birth. Measured using routinely collected maternity data (EUROKING) at hospital discharge. 3. Lumbar puncture, culture-proven infection, brachial plexus injury, treatment for jaundice, therapeutic hypothermia, measured using routinely collected maternity data (EUROKING) at hospital discharge Infant secondary outcome measures: 1. Timing of cord clamping measured using routinely collected maternity data (EUROKING) at birth 2. Apgar scores measured using routinely collected maternity data (EUROKING) at birth 3. Resuscitation measured using routinely collected maternity data (EUROKING) at birth 4. Intrapartum stillbirth or all deaths prior to neonatal unit/postnatal ward discharge measured using routinely collected neonatal and maternity data (NNRD, EUROKING) at birth and hospital discharge 5. Neonatal deaths that occurred within seven days of birth on a neonatal unit/postnatal ward measured using routinely collected maternity data (EUROKING) at birth, during admission or during readmission 6. Snapped umbilical cord prior to clamping measured using routinely collected maternity data (EUROKING) at birth 7. Skin-to-skin contact at birth measured using routinely collected maternity data (EUROKING) at birth 8. First breastfeed within the first hour measured using routinely collected maternity data (EUROKING) at birth 9. Administration of intravenous antibiotics including timing and duration measured using POOL specific and routinely collected neonatal data (NNRD, EUROKING) at hospital discharge 10. Blood culture positive with a recognised pathogen (excluding skin commensal organisms) measured using POOL specific and routinely collected neonatal data (NNRD, EUROKING) at hospital discharge 11. Highest CRP results measured using POOL-specific and routinely collected neonatal and maternity data (EUROKING) at hospital discharge 12. Successful / attempted lumbar puncture measured using routinely collected maternity data (EUROKING) at hospital discharge 13. Neonatal unit admissions measured using routinely collected maternity and neonatal data (EUROKING, NNRD) 14. Respiratory support measured using routinely collected neonatal (NNRD) at hospital discharge 15. Therapeutic hypothermia measured using routinely collected neonatal data (NNRD) at hospital discharge 16. Birth injuries measured using routinely collected maternity and neonatal data (EUROKING, NNRD) at hospital discharge 17. Treatment for jaundice measured using routinely collected maternity and neonatal data (EUROKING, NNRD) at hospital discharge 18. Readmission to the hospital within seven days of birth measured using routinely collected maternity data (EUROKING) at readmission _____ Previous 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 study start date | 01/04/2018 |
| Overall study end date | 31/03/2024 |
Eligibility
| Participant type(s) | Mixed |
|---|---|
| Age group | Mixed |
| Sex | Both |
| 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. |
| Total final enrolment | 52410 |
| Participant inclusion criteria | Current participant inclusion criteria as of 09/09/2022: 1. Women, and their infants, if the woman used water immersion at a study site during the period of data collection 2. Any women for whom water immersion analgesia is recorded in Wellbeing Software’s E3 system 3. Birth in which the foetus is partially or totally expelled under water Previous 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 |
| 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 | 01/06/2018 |
| Recruitment end date | 30/06/2022 |
Locations
Countries of recruitment
- United Kingdom
- Wales
Study participating centres
Cardiff
CF14 4YS
United Kingdom
Odstock Road
Salisbury
SP2 8BJ
United Kingdom
Rom Valley Way
Romford
RM7 0AG
United Kingdom
Blackpool
FY3 8NR
United Kingdom
Farnworth
Bolton
BL4 0JR
United Kingdom
Dartford
DA2 8DA
United Kingdom
Willesborough
Ashford
TN24 0LZ
United Kingdom
Margate
CT9 4AN
United Kingdom
Frimley
Camberley
GU16 7UJ
United Kingdom
Uxbridge
UB8 3NN
United Kingdom
Parkhurst Road
Newport
PO30 5TG
United Kingdom
Hardwick Lane
Bury St. Edmunds
IP33 2QZ
United Kingdom
Gorleston
Great Yarmouth
NR31 6LA
United Kingdom
Leicester
LE1 5WW
United Kingdom
Wythenshawe
Manchester
M23 9LT
United Kingdom
Crumpsall
Manchester
M8 5RB
United Kingdom
Gillingham
ME7 5NY
United Kingdom
Royal Victoria Infirmary
Queen Victoria Road
Newcastle upon Tyne
NE1 4LP
United Kingdom
Westbury-on-trym
Bristol
BS10 5NB
United Kingdom
Rake Lane
North Shields
NE29 8NH
United Kingdom
Oldham
OL1 2JH
United Kingdom
Truro
TR1 3LJ
United Kingdom
Middlesbrough
TS4 3BW
United Kingdom
Poplar Grove
Hazel Grove
Stockport
SK2 7JE
United Kingdom
Appley Bridge
Wigan
WN6 9EP
United Kingdom
Blackshaw Road
London
SW17 0QT
United Kingdom
Colney
Norwich
NR4 7UY
United Kingdom
Hermitage Lane
Maidstone
ME16 9QQ
United Kingdom
Tonbridge Road
Pembury
Tunbridge Wells
TN2 4QJ
United Kingdom
Sponsor information
University/education
McKenzie House
30-36 Newport Road
Cardiff
CF24 0DE
Wales
United Kingdom
| Phone | +44 (0)29 2087 4000 |
|---|---|
| resgov@cardiff.ac.uk | |
| Website | www.cardiff.ac.uk |
"ROR" |
https://ror.org/03kk7td41 |
Funders
Funder type
Government
Government organisation / National government
- Alternative name(s)
- NIHR Health Technology Assessment Programme, HTA
- Location
- United Kingdom
Results and Publications
| Intention to publish date | 23/06/2024 |
|---|---|
| Individual participant data (IPD) Intention to share | No |
| IPD sharing plan summary | Not expected to be made available |
| Publication and dissemination plan | Planned publication in a high-impact peer reviewed journal. |
| IPD sharing plan | Current IPD sharing statement as of 09/09/2022: The datasets generated during and/or analysed during the current study are not expected to be made available, for further information please contact SandersJ3@cardiff.ac.uk or roblingmr@cardiff.ac.uk _____ Previous 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). |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Protocol article | protocol | 08/01/2021 | 11/01/2021 | Yes | No |
| Statistical Analysis Plan | version 1.0 | 30/06/2022 | 13/06/2023 | No | No |
| HRA research summary | 26/07/2023 | No | No | ||
| Results article | 10/06/2024 | 16/01/2025 | Yes | No |
Additional files
Editorial Notes
16/01/2025: Publication reference added.
13/02/2024: The overall study end date was changed from 31/03/2023 to 31/03/2024.
13/06/2023: The statistical analysis plan was uploaded as an additional file.
15/03/2023: The total final enrolment was added.
09/03/2023: The intention to publish date was changed from 31/03/2024 to 23/06/2024.
09/09/2022: The following changes have been made and the plain English summary updated accordingly:
1. Ethics approval has been added.
2. The study design has been changed from "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" to "Cohort study with a nested qualitative component, using a combination of data captured retrospectively and prospectively (January 2015 to June 2022) in electronic NHS maternity and neonatal information systems".
3. The trial type has been changed from "Treatment" to "Other".
4. The condition has been changed from "Waterbirth" to "Birth in water following water immersion during labour".
5. The interventions have been changed.
6. The secondary outcome measures have been changed.
7. The participant inclusion criteria have been changed.
8. The recruitment end date has been changed from 30/11/2020 to 30/06/2022.
9. Salisbury District Hospital, Queens Hospital, Blackpool Victoria Hospital, Royal Bolton Hospital, Darent Valley Hospital, The William Harvey Hospital, Queen Elizabeth The Queen Mother Hospital, Frimley Park Hospital, Hillingdon Hospital, St Mary's Hospital, West Suffolk Hospital, James Paget University Hospital, Leicester Royal Infirmary, Wythenshawe Hospital, North Manchester General Hospital, Medway Maritime Hospital, Royal Victoria Infirmary, Southmead Hospital, North Tyneside Hospital, The Royal Oldham Hospital, The Royal Oldham Hospital, Royal Cornwall Hospital, The James Cook University Hospital, Stepping Hill Hospital, Wrightington Hospital, St George’s Hospital, Norfolk and Norwich University Hospital and Maidstone Hospital have been added to the trial participating centres.
10. The IPD sharing statement and summary have been updated.
11. A public contact has been added.
06/09/2021: The following changes were made to the trial record:
1. The overall end date was changed from 31/08/2021 to 31/03/2023.
2. The intention to publish date was changed from 31/08/2022 to 31/03/2024.
3. The plain English summary was updated to reflect these changes.
11/01/2021: Publication reference added.
15/06/2020: The contact details were changed.
