Does water birth affect the risk of obstetric anal sphincter injury? Development of a prognostic model

Water birth: a systematic review and meta-analysis of maternal and neonatal outcomes

OBJECTIVE

This systematic review and meta-analysis aimed to conduct a thorough and contemporary assessment of maternal and neonatal outcomes associated with water birth in comparison with land-based birth.

DATA SOURCES

We conducted a comprehensive search of PubMed, EMBASE, CINAHL, and gray literature sources, from inception to February 28, 2023.

STUDY ELIGIBILITY CRITERIA

We included randomized and nonrandomized studies that assessed maternal and neonatal outcomes in patients who delivered either conventionally or while submerged in water.

METHODS

Pooled unadjusted odds ratios with 95% confidence intervals were calculated using a random-effects model (restricted maximum likelihood method). We assessed the 95% prediction intervals to estimate the likely range of future study results. To evaluate the robustness of the results, we calculated fragility indices. Maternal infection was designated as the primary outcome, whereas postpartum hemorrhage, perineal lacerations, obstetrical anal sphincter injury, umbilical cord avulsion, low Apgar scores, neonatal aspiration requiring resuscitation, neonatal infection, neonatal mortality within 30 days of birth, and neonatal intensive care unit admission were considered secondary outcomes.

RESULTS

Of the 20,642 articles identified, 52 were included in the meta-analyses. Based on data from observational studies, water birth was not associated with increased probability of maternal infection compared with land birth (10 articles, 113,395 pregnancies; odds ratio, 0.93; 95% confidence interval, 0.76-1.14). Patients undergoing water birth had decreased odds of postpartum hemorrhage (21 articles, 149,732 pregnancies; odds ratio, 0.80; 95% confidence interval, 0.68-0.94). Neonates delivered while submerged in water had increased odds of cord avulsion (10 articles, 91,504 pregnancies; odds ratio, 1.75; 95% confidence interval, 1.38-2.24) and decreased odds of low Apgar scores (21 articles, 165,917 pregnancies; odds ratio, 0.69; 95% confidence interval, 0.58-0.82), neonatal infection (15 articles, 53,635 pregnancies; odds ratio, 0.64; 95% confidence interval, 0.42-0.97), neonatal aspiration requiring resuscitation (19 articles, 181,001 pregnancies; odds ratio, 0.60; 95% confidence interval, 0.43-0.84), and neonatal intensive care unit admission (30 articles, 287,698 pregnancies; odds ratio, 0.56; 95% confidence interval, 0.45-0.70).

CONCLUSION

When compared with land birth, water birth does not appear to increase the risk of most maternal and neonatal complications. Like any other delivery method, water birth has its unique considerations and potential risks, which health care providers and expectant parents should evaluate thoroughly. However, with proper precautions in place, water birth can be a reasonable choice for mothers and newborns, in facilities equipped to conduct water births safely.

Is water delivery a good idea to prevent obstetric anal sphincter injuries in low risk primiparae? An exploratory study in a Swiss public teaching hospital

OBJECTIVE

Obstetric anal sphincter injuries are feared perineal injuries that are associated with increased pelvic floor disorders. The knowledge of influencing factors as the mode of delivery is therefore important. The aim of this study is to compare the rate of obstetric anal sphincter injuries in primiparae after water and bed deliveries.

STUDY DESIGN

In this retrospective cohort study 3907 primiparae gave birth in water or on a bed in a Swiss teaching hospital. The diagnosis of obstetric anal sphincter injuries was confirmed by a consultant of obstetrics and gynecology and treated by them. The rates of these injuries after water and bed births were compared. Subgroup analysis was performed to detect possible associative factors, such as birth weight, episiotomy, use of oxytocin in first and second stage of labor.

RESULTS

1844 (47.2 %) of the primiparae had a water delivery and 2063 (52.8 %) a bed delivery. 193 (4.94 %) were diagnosed with obstetric anal sphincter injuries, of which 68 (3.7 %) had a water delivery and 125 (6.1 %) a bed delivery, p < 0.001. Subgroup analysis revealed that, in the first and second stage of labor, the rate of obstetric anal sphincter injuries with oxytocin was significantly lower in water than in bed deliveries; p = 0.025, p < 0.017, respectively. The rate of obstetric anal sphincter injuries in the birth weight or episiotomy subgroups did not reach significance.

CONCLUSIONS

In a teaching hospital setting with standardized labor management, primiparae with a water delivery have the lowest risk for obstetric anal sphincter injuries.

Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?

Pelvic floor disorders after childbirth have distressing lifelong consequences for women, requiring more than 300,000 women to have surgery annually. This represents approximately 10% of the 3 million women who give birth vaginally each year. Vaginal birth is the largest modifiable risk factor for prolapse, the pelvic floor disorder most strongly associated with birth, and is an important contributor to stress incontinence. These disorders require 10 times as many operations as anal sphincter injuries. Imaging shows that injuries of the levator ani muscle, perineal body, and membrane occur in up to 19% of primiparous women. During birth, the levator muscle and birth canal tissues must stretch to more than 3 times their original length; it is this overstretching that is responsible for the muscle tear visible on imaging rather than compression or neuropathy. The injury is present in 55% of women with prolapse later in life, with an odds ratio of 7.3, compared with women with normal support. In addition, levator damage can affect other aspects of hiatal closure, such as the perineal body and membrane. These injuries are associated with an enlarged urogenital hiatus, now known as antedate prolapse, and with prolapse surgery failure. Risk factors for levator injury are multifactorial and include forceps delivery, occiput posterior birth, older maternal age, long second stage of labor, and birthweight of >4000 g. Delivery with a vacuum device is associated with reduced levator damage. Other steps that might logically reduce injuries include manual rotation from occiput posterior to occiput anterior, slow gradual delivery, perineal massage or compresses, and early induction of labor, but these require study to document protection. In addition, teaching women to avoid pushing against a contracted levator muscle would likely decrease injury risk by decreasing tension on the vulnerable muscle origin. Providing care for women who have experienced difficult deliveries can be enhanced with early recognition, physical therapy, and attention to recovery. It is only right that women be made aware of these risks during pregnancy. Educating women on the long-term pelvic floor sequelae of childbirth should be performed antenatally so that they can be empowered to make informed decisions about management decisions during labor.

Alternate Birth Strategies

Community birth is defined as birth that occurs outside the hospital setting. Birthing in a birth center can be safe for certain patient populations. Home birth can also be safe in well-selected patient with a well-established transfer infrastructure should an emergency occur. Unfortunately, many areas of the United States and the world do not have this infrastructure, limiting access to safe community birth. Immersion during labor has been associated with decreased need for epidural and pain medication. Delivery should not occur in water due to concerns for infection and cord avulsion. Umbilical cord non-severance (also called lotus birth) and placentophagy should be counseled against due to well-documented risks without clear benefit. Birth plans and options should be regularly discussed during pregnancy visits.

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

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.

Risk of obstetric anal sphincter injuries at the time of admission for delivery: A clinical prediction model

OBJECTIVE

To develop and validate a model to predict obstetric anal sphincter injuries (OASIS) using only information available at the time of admission for labour.

DESIGN

A clinical predictive model using a retrospective cohort.

SETTING

A US health system containing one community and one tertiary hospital.

SAMPLE

A total of 22 873 pregnancy episodes with in-hospital delivery at or beyond 21 weeks of gestation.

METHODS

Thirty antepartum risk factors were identified as candidate variables, and a prediction model was built using logistic regression predicting OASIS versus no OASIS. Models were fit using the overall study population and separately using hospital-specific cohorts. Bootstrapping was used for internal validation and external cross-validation was performed between the two hospital cohorts.

MAIN OUTCOME MEASURES

Model performance was estimated using the bias-corrected concordance index (c-index), calibration plots and decision curves.

RESULTS

Fifteen risk factors were retained in the final model. Decreasing parity, previous caesarean birth and cardiovascular disease increased risk of OASIS, whereas tobacco use and black race decreased risk. The final model from the total study population had good discrimination (c-index 0.77, 95% confidence interval [CI] 0.75-0.78) and was able to accurately predict risks between 0 and 35%, where average risk for OASIS was 3%. The site-specific model fit using patients only from the tertiary hospital had c-stat 0.74 (95% CI 0.72-0.77) on community hospital patients, and the community hospital model was 0.77 (95%CI 0.76-0.80) on the tertiary hospital patients.

CONCLUSIONS

OASIS can be accurately predicted based on variables known at the time of admission for labour. These predictions could be useful for selectively implementing OASIS prevention strategies.

Comparative Efficacy of Water and Conventional Delivery during Labour: A Systematic Review and Meta-Analysis

In many maternal settings, water delivery is widely available for women who do not have an increased risk of complications during childbirth. Soaking in water during labor has been associated with a number of maternal benefits. However, the situation of water birth is not well known, there is lack of hard evidence on safety, and little is known about the characteristics of women who give birth in water. In this paper, we have explored the effects of water delivery compared to the conventional delivery on the health of mothers and babies. For this purpose, clinical trials were conducted including women in labor, in which participants were treated with water labor or conventional labor, respectively, in the experimental and control group. In this analysis, we have selected 17 eligible studies which included 175654 participants. Compared to the conventional birth group, the risk of Apgar score <7 at 5 min of age in the water birth group dropped by 28% (OR = 0.72, 95% CI: 0.52-1.00, I 2 = 25%, P=0.05). Also, the duration of labor was shorter the in water birth group whatever the labor stage was. The patients who underwent water birth showed an obviously lower rate of neonatal intensive care unit (NICU) admission (OR = 0.58, 95% CI: 0.39-0.86, I 2 = 53%, P=0.007). In this meta-analysis, it was seen that water delivery has clinical significance in alleviating the pain of mothers, promoting the safety of mothers and infants, and reducing postpartum complications.

Waterbirth: a national retrospective cohort study of factors associated with its use among women in England

Background

Waterbirth is widely available in English maternity settings for women who are not at increased risk of complications during labour. Immersion in water during labour is associated with a number of maternal benefits. However for birth in water the situation is less clear, with conclusive evidence on safety lacking and little known about the characteristics of women who give birth in water.

This retrospective cohort study uses electronic data routinely collected in the course of maternity care in England in 2015–16 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.

Methods

Data were obtained from three population level electronic datasets linked together for the purposes of a national audit of maternity care. The study cohort included women who had no risk factors requiring them to give birth in an obstetric unit according to national guidelines. Multivariate logistic regression models were used to examine maternal (postpartum haemorrhage of 1500mls or more, obstetric anal sphincter injury (OASI)) and neonatal (Apgar score less than 7, neonatal unit admission) outcomes associated with waterbirth.

Results

46,088 low and intermediate risk singleton term spontaneous vaginal births in 35 NHS Trusts in England were included in the analysis cohort. Of these 6264 (13.6%) were recorded as having occurred in water. Waterbirth was more likely in older women up to the age of 40 (adjusted odds ratio (adjOR) for age group 35–39 1.27, 95% confidence interval (1.15,1.41)) and less common in women under 25 (adjOR 18–24 0.76 (0.70, 0.82)), those of higher parity (parity ≥3 adjOR 0.56 (0.47,0.66)) or who were obese (BMI 30–34.9 adjOR 0.77 (0.70,0.85)). Waterbirth was also less likely in black (adjOR 0.42 (0.36, 0.51)) and Asian (adjOR 0.26 (0.23,0.30)) women and in those from areas of increased socioeconomic deprivation (most affluent versus least affluent areas adjOR 0.47 (0.43, 0.52)).

There was no association between delivery in water and low Apgar score (adjOR 0.95 (0.66,1.36)) or incidence of OASI (adjOR 1.00 (0.86,1.16)). There was an association between waterbirth and reduced incidence of postpartum haemorrhage (adjOR 0.68 (0.51,0.90)) and neonatal unit admission (adjOR 0.65 (0.53,0.78)).

Conclusions

In this large observational cohort study, there was no association between waterbirth and specific adverse outcomes for either the mother or the baby. There was evidence that white women from higher socioeconomic backgrounds were more likely to be recorded as giving birth in water. Maternity services should focus on ensuring equitable access to waterbirth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03724-6.

Are women attending a midwifery-led birthing center at increased risk of anal sphincter injury?

INTRODUCTION AND HYPOTHESIS

In recent years there has been renewed interest in midwifery-led care for women, with studies reporting similar neonatal outcomes despite lower rates of intervention in midwifery-led birthing centers. Research into obstetric anal sphincter injuries (OASI) in these birthing centers is scarce. The objective of this study was to compare the rate of OASI after spontaneous vaginal delivery in nulliparous women in consultant or midwifery-led units over a ten-year period.

METHODS

All spontaneous vaginal deliveries in nulliparous women from 2008 to 2017 were analyzed in a single-center retrospective study. Women who had neuraxial analgesia were excluded. The primary endpoint was OASI. Labor characteristics in both groups were compared, and a multiple regression model was created.

RESULTS

During the study period, there were 3260 spontaneous vaginal deliveries in nulliparous women; 75.7% (2467/3260) delivered in the consultant-led unit and 24.3% (793/3260) in the midwifery-led unit (MLU). Women delivering in the MLU had a greater risk of anal sphincter injury than those delivering in the CLU (4.9% [39/793] vs 2.5% [62/2467], OR 2.01, 95% CI 1.32 - 3.01). Significant risk factors that increased the risk of OASI on regression analysis were birthweight and delivery in the midwifery-led unit.

CONCLUSIONS

Women delivering in the midwifery-led unit appear to be at double the risk of OASI when compared to those delivering in the consultant-led unit. These results are in contrast to previous studies in midwifery-led centers. This difference may be site-specific and further research is required before these results form part of patient counseling.

Predictors of obstetric anal sphincter injury during waterbirth: a secondary analysis of a prospective observational study

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injury (OASI) during childbirth is associated with urino-genital pain and dysfunction. Waterbirth is a popular birth choice for women, but controversy remains around the risk of OASI during waterbirth. This study reports on the incidence of OASI, and factors associated with OASI, for a cohort of women who gave birth in water.

METHODS

This secondary analysis used prospectively collected data from 2,908 women who gave birth in water in a hospital setting. The incidence of OASI was calculated. Univariable and multivariable logistic regression analysis evaluated factors associated with OASI.

RESULTS

The incidence of OASI was 1.9% (95% confidence interval (CI) 1.4, 2.4) for all women. In nulliparae it was higher (3.2%, 95% CI 2.3, 4.3) than in multiparae (0.9%, 95% CI 0.5, 1.4). In the multivariable analysis, two variables were associated with OASI; multiparity was negatively associated with OASI (adjusted odds ratio [aOR] 0.24, 95% CI 0.12, 0.50, p < 0.001), and birth weight was positively associated with OASI (aOR 1.001, 95% CI 1.000, 1.002, p = 0.02). A "hands-on" technique was used during only 13% of births. A birth position supporting a flexible sacrum did not influence OASI risk.

CONCLUSIONS

A low incidence of OASI was found for this cohort of women. The low proportion of midwives using a hands-on technique suggests that it may not be required in waterbirth.