Neonatal Mortality Risk Increased for Home Midwife Births

Troy Brown, RN

April 03, 2014

( UPDATED April 7, 2014 ) Total neonatal mortality risk was almost 4 times greater in babies birthed at home by midwives compared with babies delivered by hospital midwives, according to an analysis of data from almost 14 million deliveries in the United States. In addition, early neonatal mortality risk was almost 7 times higher in the home birth group than in the hospital birth group.

Amos Grünebaum, MD, a specialist in maternal–fetal medicine (high-risk pregnancy), from the Department of Obstetrics and Gynecology, Weill Medical College of Cornell University, New York City, and colleagues report their findings in an article published online March 24 in the American Journal of Obstetrics and Gynecology.

"It's impressive amounts of data...it's a good study," James Byrne, MD, chair, Department of Ob-Gyn, Santa Clara Valley Medical Center, San Jose, and affiliated clinical professor, Stanford University School of Medicine, California, told Medscape Medical News.

The researchers analyzed a data set from 2006 to 2009 and linked birth/infant deaths from almost 14 million deliveries in the United States to examine early and total neonatal mortality by birth setting (hospital, birthing center, home) and provider. Early deaths were defined as those occurring within 7 days of birth, and total deaths included mortality through the first 28 days after birth. The authors restricted their analysis to term singleton births (37+ weeks and newborn weight ≥2500 g) with no documented congenital malformations.

Provider categories included hospital midwives, hospital physicians, freestanding birthing center midwives, home midwives, and home "other" (emergency situations, such as unattended births and "any other person delivering the baby, such as a husband or family member, emergency medical technician, or taxi driver"). The category of hospital midwives included certified nurse midwives (CNM), other midwives, and hospital midwives; the category of home midwives included CNM, other midwives, and home midwives.

The total neonatal mortality risk was significantly higher for babies delivered at home by midwives compared with those delivered by hospital midwives (1.26/1000 births; risk ratio [RR], 3.87 vs 0.32 per 1000 births; P < .001). The risk for infants delivered by physicians in the hospital was higher than for those delivered by hospital midwives but lower than for home midwife births (0.55/1000 births; RR, 1.69).

The early neonatal mortality risk was also significantly higher for those delivered at home by midwives compared with babies delivered by hospital midwives (0.93/1000 births; RR, 6.6 vs 0.14 per 1000 births; P < .001). The risk for infants delivered by physicians in the hospital was higher than for those delivered by hospital midwives but much lower than for home midwife births (0.29/1000; RR, 2.04).

"The higher neonatal mortality rate for hospital physicians when compared to hospital midwives almost certainly reflects the fact that hospital physicians deliver a higher-risk population than hospital midwives and deliver patients with complications transferred from the hospital midwifery service to the hospital physician service," the authors write.

Part of the increased risk for babies born outside of the hospital is because when medical interventions such as emergency pedriatic care and equipment are needed, they are not available, Dr. Byrne explained.

Babies born at home by "others" had an excess total neonatal mortality of 15.42/10,000 births and newborns delivered by midwives at home had an excess of 9.32/10,000 births compared with midwife hospital births.

Risks Higher for Home Births of First-Born and 41 or More Weeks of Gestational Age

Neonatal mortality is even higher for first-born infants and those delivered at 41 or more weeks of gestational age.

Infants delivered at home by midwives to women with a first birth had a significantly higher risk for total neonatal mortality than babies delivered by hospital midwives (2.19/1000; RR, 6.74 vs 0.33 per 1000 births; P < .001) and a neonatal mortality twice that of women with a later birth (2.19 vs 0.96 per 1000 births; P < .001).

Midwife home births of 41 or more weeks of gestational age also had a significantly higher risk for total neonatal mortality than those delivered by hospital midwives (1.84/1000; RR, 6.76 vs 0.27 per 1000 births; P < .001).

Early mortality followed a similar pattern. First-born infants delivered by midwives at home had a significantly higher risk for early neonatal mortality compared with those delivered by hospital midwives (1.82/1000; RR, 13.62 vs 0.13 per 1000 births; P < .001) and an early neonatal mortality almost 3 times that of those born to women who had given birth before (1.82 vs 0.66 per 1000 births; P < .001).

Midwife home births of 41 or more weeks of gestational age had a significantly higher risk for early neonatal mortality compared with those delivered by hospital midwives (1.26/1000; RR, 10.28 vs 0.12 per 1000 births; P < .001).

Different Populations Being Studied

Recent data regarding the risks related to various birth settings have been inconsistent. "These numbers are striking to me how high they're saying the increased risk is," Dr. Byrne noted.

"Many of the studies published in the last 15 years have been comparing 2 different groups. The data that usually appears in midwifery journals is usually looking at populations of women who are risk-appropriate.... [T]hey're low-risk women, and if they have identified risk factors for preterm birth or cesarean, they're usually not included as part of the data analysis," Dr. Byrne explained.

"Most of the data being published in medical journals is using a mixed-risk population.... [I]t's blended between low-risk women and women with risk factors," he added. "Each group tends to be accurately reporting what their experience is for their populations."

In a published statement about the study, the American of College of Nurse Midwives (ACNM) questions several aspects of the study by Dr. Grünebaum and colleagues. "First, there are serious questions about the accuracy of the vital statistics data upon which this study is based," the statement says. Birth certificates may not be filled out completely or by the provider attending the birth. In addition, it is not always clear from such records whether a birth was a planned home birth.

Perhaps more important, grouping CNMs with all other midwives reduces the value of the results. "There is no way to determine the credentials, education, or licensure status of a person referred to as 'other midwife,' " the statement continues.

"ACNM has had the long-standing position that women should have access to reliable information and be fully informed, have access to quality health care providers and the appropriate birth setting of their choice — home, birth center, or hospital," the statement concludes.

The authors also presented their results at the 34th annual meeting of the Society for Maternal-Fetal Medicine in New Orleans, Louisiana, February 3-8, 2014. The authors and Dr. Byrne have disclosed no relevant financial relationships.

Am J Obstet Gynecol. Published online March 24, 2014. Abstract

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