Systematic review and meta-analysis to examine intrapartum interventions, and maternal and neonatal outcomes following immersion in water during labour and waterbirth

Abstract

Objectives: Water immersion during labour using a birth pool to achieve relaxation and pain relief during the first and possibly part of the second stage of labour is an increasingly popular care option in several countries. It is used particularly by healthy women who experience a straightforward pregnancy, labour spontaneously at term gestation and plan to give birth in a midwifery led care setting. More women are also choosing to give birth in water. There is debate about the safety of intrapartum water immersion, particularly waterbirth. We synthesised the evidence that compared the effect of water immersion during labour or waterbirth on intrapartum interventions and outcomes to standard care with no water immersion. A secondary objective was to synthesise data relating to clinical care practices and birth settings that women experience who immerse in water and women who do not.

Design: Systematic review and meta-analysis.

Data sources: A search was conducted using CINAHL, Medline, Embase, BioMed Central and PsycINFO during March 2020 and was replicated in May 2021.

Eligibility criteria for selecting studies: Primary quantitative studies published in 2000 or later, examining maternal or neonatal interventions and outcomes using the birthing pool for labour and/or birth.

Data extraction and synthesis: Full-text screening was undertaken independently against inclusion/exclusion criteria in two pairs. Risk of bias assessment included review of seven domains based on the Robbins-I Risk of Bias Tool. All outcomes were summarised using an OR and 95% CI. All calculations were conducted in Comprehensive Meta-Analysis V.3, using the inverse variance method. Results of individual studies were converted to log OR and SE for synthesis. Fixed effects models were used when I² was less than 50%, otherwise random effects models were used. The fail-safe N estimates were calculated to determine the number of studies necessary to change the estimates. Begg's test and Egger's regression risk assessed risk of bias across studies. Trim-and-fill analysis was used to estimate the magnitude of effect of the bias. Meta-regression was completed when at least 10 studies provided data for an outcome.

Results: We included 36 studies in the review, (N=157 546 participants). Thirty-one studies were conducted in an obstetric unit setting (n=70 393), four studies were conducted in midwife led settings (n=61 385) and one study was a mixed setting (OU and homebirth) (n=25 768). Midwife led settings included planned home and freestanding midwifery unit (k=1), alongside midwifery units (k=1), planned homebirth (k=1), a freestanding midwifery unit and an alongside midwifery unit (k=1) and an alongside midwifery unit (k=1). For water immersion, 25 studies involved women who planned to have/had a waterbirth (n=151 742), seven involved water immersion for labour only (1901), three studies reported on water immersion during labour and waterbirth (n=3688) and one study was unclear about the timing of water immersion (n=215).Water immersion significantly reduced use of epidural (k=7, n=10 993; OR 0.17 95% CI 0.05 to 0.56), injected opioids (k=8, n=27 391; OR 0.22 95% CI 0.13 to 0.38), episiotomy (k=15, n=36 558; OR 0.16; 95% CI 0.10 to 0.27), maternal pain (k=8, n=1200; OR 0.24 95% CI 0.12 to 0.51) and postpartum haemorrhage (k=15, n=63 891; OR 0.69 95% CI 0.51 to 0.95). There was an increase in maternal satisfaction (k=6, n=4144; OR 1.95 95% CI 1.28 to 2.96) and odds of an intact perineum (k=17, n=59 070; OR 1.48; 95% CI 1.21 to 1.79) with water immersion. Waterbirth was associated with increased odds of cord avulsion (OR 1.94 95% CI 1.30 to 2.88), although the absolute risk remained low (4.3 per 1000 vs 1.3 per 1000). There were no differences in any other identified neonatal outcomes.

Conclusions: This review endorses previous reviews showing clear benefits resulting from intrapartum water immersion for healthy women and their newborns. While most included studies were conducted in obstetric units, to enable the identification of best practice regarding water immersion, future birthing pool research should integrate factors that are known to influence intrapartum interventions and outcomes. These include maternal parity, the care model, care practices and birth setting.

Prospero registration number: CRD42019147001.

Keywords: Maternal medicine; PRIMARY CARE; Pain management.

Figure 1

PRISMA 2020 flow diagram for new systematic reviews which included searches of databases, registers and other sources. PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Figure 2

Risk of bias assessment.

Figure 3

Forest plot of synthesis of labour induction. IV, inverse variance.

Figure 4

Forest plot of synthesis of amniotomy. IV, inverse variance.

Figure 5

Forest plot of synthesis of augmentation of labour. IV, inverse variance.

Figure 6

Forest plot of synthesis of opioid use. IV, inverse variance.

Figure 7

Forest plot of synthesis of epidural use. IV, inverse variance.

Figure 8

Forest plot of synthesis of pain. IV, inverse variance.

Figure 9

Forest plot of synthesis of caesarean delivery. IV, inverse variance.

Figure 10

Forest plot of synthesis of shoulder dystocia. IV, inverse variance.

Figure 11

Forest plot of synthesis of intact perineum. IV, inverse variance.

Figure 12

Forest plot of synthesis of obstetric anal sphincter injuries. IV, inverse variance.

Figure 13

Forest plot of synthesis of episiotomy. IV, inverse variance.

Figure 14

Forest plot of synthesis of postpartum haemorrhage.

Figure 15

Forest plot of synthesis of manual removal of the placenta. IV, inverse variance.

Figure 16

Forest plot of synthesis for maternal infection. IV, inverse variance.

Figure 17

Forest plot of synthesis of maternal satisfaction measures. IV, inverse variance.

Figure 18

Forest plot of synthesis of 5 min APGAR. IV, inverse variance.

Figure 19

Forest plot of synthesis of neonatal resuscitation. IV, inverse variance.

Figure 20

Forest plot of synthesis of transient tachypnoea of the newborn. IV, inverse variance.

Figure 21

Forest plot of synthesis of respiratory distress. IV, inverse variance.

Figure 22

Forest plot of synthesis of neonatal death. IV, inverse variance.

Figure 23

Forest plot of synthesis of cord avulsion. IV, inverse variance.

Figure 24

Forest plot of synthesis of breastfeeding initiation. IV, inverse variance.