Friday, July 13, 2012

Waterbirth study shows significant perinatal mortality and morbidity

Perinatal mortality and morbidity among babies delivered in water: surveillance study and postal survey was published in the BMJ in 1999. It is an attempt to study the outcomes of 4,030 deliveries in England and Wales. The study suffers from the serious flaw that it does not have a control group with similar characteristics. The authors compare the mortality and morbidity to women delivering a baby from the vertex presentation. This could contain (and likely does contain) many women who are much higher risk than the women in the waterbirth group.

Nonetheless, it is instructive to look at the results. Out of 4,030 babies delivered in water, 34 were admitted to intensive care nurseries, of which 3 subsequently died. According to the study:

All three postpartum deaths were associated with abnormal pathological findings: one baby died aged 3 days with neonatal herpes infection; one died aged 30 minutes with an intracranial haemorrhage after precipitate delivery; and the third, who died aged 8 hours, was found to have hypoplastic lungs at postmortem examination.

Of the 32 survivors, 13 required respiratory support (ventilation or continuous positive airways pressure-6 or head-box oxygen-7). Fifteen of the survivors had lower respiratory tract problems, variously labelled as pneumonia, transient tachypnoea of the newborn, or "wet lung"-9; suspected aspiration-3; meconium aspiration-1; water aspiration-1; and "freshwater drowning"-1.
Hypoxic ischaemic encephalopathy grade 2 or 3 or perinatal asphyxia was reported in 5 surviving children, including the baby in whom freshwater drowning was diagnosed...

In the 32 survivors, 15 had other diagnoses or reasons for admission. Five babies had a snapped umbilical cord (of whom 1 required a transfusion, 1 developed hypoxic ischaemic encephalopathy grade 2, and 1 had a chromosomal abnormality). One further baby had a chromosomal abnormality; one developed hypoxic ischaemic encephalopathy grade 3 and had transposition of the great arteries; three had stridor; and one had shoulder dystocia. No clear reason or diagnosis was given for the remaining 4 babies.
In summary, out of 4,030 deliveries in water, 35 babies suffered serious problems and 3 subsequently died. It is unclear if any of the deaths can be attributed to delivery in water. However, of the 32 survivors who were admitted to the NICU, 13 had significant respiratory problems including pneumonia, meconium aspiration, water aspiration, and drowning. Other complications attributable to water birth include 5 babies who had significant hemorrhage due to snapped umbilical cord. In all, 18 babies had serious complications directly attributable to waterbirth. The risk of serious complications necessitating prolonged NICU admissions was 4.5/1000.

The authors concluded that these morbidity and mortality are similar to rates in other studies, but they fail to control for risk, so highly likely that the waterbirth group was much lower risk than the comparison group.

In my judgment, this is a pretty serious indictment of waterbirth.

This piece first appeared on Homebirth Debate in August 2006.

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