June 26, 2014 — Summary of "Waterbirth: An Integrative Analysis of Peer-Reviewed Literature," Nutter et al., Journal of Midwifery & Women's Health, May/June 2014.
"[D]espite a growing body of evidence regarding its safety and increasing international use," only 229 U.S. hospitals offered waterbirth in 2009, according to researchers led by certified nurse-midwife Elizabeth Nutter.
The researchers developed a study "to critically analyze peer-reviewed research on maternal and neonatal outcomes of waterbirth," aiming "to help identify gaps in knowledge and to inform policy statements and evidence-based clinical practice in the United States."
They noted that "[w]aterbirth is defined as fetal emergence underwater" and is not the same as laboring in water "before giving birth conventionally." Whereas the "safety and benefits of laboring in water have been well established," literature reviews focusing on waterbirth have largely "been restricted to scant data from a few randomized controlled trials conducted to date," they added.
The researchers conducted a search of peer-reviewed literature via electronic databases using key words such as "waterbirth," "alternative birth method," "hydrotherapy" and "labor," among other relevant terms.
They created a matrix to organize the articles thematically, facilitate their data analysis and enable synthesis of perinatal outcomes.
The review included two randomized controlled trials and 36 observational studies. The studies included waterbirths in 34 hospitals and three birth centers, although one study looked at home waterbirths in addition to those at hospitals and birth centers.
In total, the studies covered 31,453 unique waterbirths. The studies were conducted in 11 countries, with the greatest number from the U.K. (16 studies) and only one study from the U.S.
Multiple studies found "that waterbirth is associated with the decreased use of episiotomy compared with conventional birth," as well as a "higher incidence of intact perineums," the review found. Among women who experienced perineal lacerations, those who gave birth in water tended to have less-severe lacerations than those with conventional births, the findings suggested.
Five studies found that maternal infection rates were the same among women after waterbirth or conventional birth. The researchers noted that while the reviewed studies were "reassuring that waterbirth is not associated with an excessive infection risk," the methodology of most of the studies limited the "interpretation and generalization of results" on infection rates.
Although few studies thoroughly examined blood loss, "research generally supports an association between waterbirth and the equivalent or decreased postpartum blood loss compared to conventional birth," according to the review.
The evidence reviewed suggested that waterbirth is associated with use of less analgesia than conventional birth, although overlapping data on water labor and waterbirth in most of the studies made it difficult to interpret the results, the researchers found.
All four studies that evaluated women's satisfaction with childbirth found that satisfaction levels were higher after waterbirth than conventional birth.
"Overall, results suggest there is no difference in Apgar scores after waterbirth versus conventional birth," the researchers wrote, noting that Apgar scores were the most commonly assessed neonatal outcome in the studies.
Eleven studies found no differences in neonatal infection rates between waterbirth and conventional birth, while three studies that lacked comparison groups found "a low incidence of [neonatal] infection and antibiotic administration," the review found. Overall, "the risk of neonatal infection following waterbirth appears to be low, and data are reassuring despite methodological issues that prevent definitive conclusions."
Aggregate data from 10 studies found comparable rates of neonatal intensive care unit admissions after waterbirth and conventional birth.
The review also found that "[n]eonatal injury and death is uncommon after waterbirth," with the most robust study finding that the neonatal mortality rate after waterbirth "is comparable or favorable compared to low-risk populations following conventional birth."
Discussion and Conclusions
The researchers noted that there are "significant limitations" to existing waterbirth research, including study design, methodology and "the inability to control for factors inherent to the model of care in which hydrotherapy was provided." Specifically, waterbirth is typically a part of a maternity care model "that values the promotion of physiologic childbirth and/or nonintervention in the absence of complications" and likely impacts maternal and neonatal outcomes in multiple ways.
On the whole, waterbirth research "demonstrates that risks associated with waterbirth for women and neonates are minimal, and outcomes are comparable to those expected in healthy populations," the researchers wrote. They added, "As such, existing data support trained professionals in offering the practice to healthy women using evidence-based practice guidelines."