Debate over an analysis of the safety of home birth continues, as the journal that published the study, the American Journal of Obstetrics and Gynecology, has released a series of letters critiquing the study, along with replies from three of the original six authors of the study, whose first author was Joseph Wax, a specialist in maternal fetal medicine at the Maine Medical Center in Portland.

A separate critique of the study has also been published by a group of four childbirth experts and one physicist, Carl Michal, who found that the online tool used to calculate some of the results of the Wax study was flawed.

The Wax study, published last year, included a meta-analysis of previously published papers, and found that home birth caused a two-to-threefold higher risk of death among newborns than hospital birth. However, its methods were heavily criticized, and the AJOG convened an investigation into the paper late last year.

The investigation concluded that the paper did not need to be retracted, but found that there were errors in its calculations. The investigation found that other issues raised by critics were “subjective, and should be debated openly.” Now, those issues are being debated in the pages of the journal.

The issues raised by the critics include a wide range of allegations. For instance, one letter claims that the study is misleading, because it only briefly mentions one of its findings: that when home births were attended by certified nurse-midwives, the difference in newborn deaths disappeared. Others question why a large Dutch study of home and hospital births was excluded from the study. Another letter says that the study does not meet the technical reporting requirements of the AJOG itself, while another, published by professor of midwifery and women’s health Jane Sandall of King’s College London, takes Wax’s team and the AJOG to task for publishing a “misleading” press release that emphasized the higher newborn death rate found in the study.

“These practices are unethical, causing harm through unfounded confusion and fear, and misleading policy makers and the public,” Sandall writes.

Wax and his colleagues strongly defend their work. “Harboring no bias, we embarked on the study to examine an important clinical issue. Although our findings may be unpopular in certain quarters, they result from appropriate rigorous scientific methods that have undergone appropriate peer review,” they write.

They say that since most home births in the United States do not take place under the care of a certified nurse midwife, their decision not to highlight the role of nurse-midwives in their study is justified.

They say that the Dutch study was left out because it did not include data on newborn deaths after seven days, while their study aimed to look at newborn deaths up to 28 days. (The author of the Dutch study, Ank de Jonge, has said that the data on newborn deaths from 7 to 28 days is available and that she would have analyzed it for the meta-analysis had she been contacted by Wax’s team.)

Wax and colleagues also respond to each of the alleged methodological shortcomings of their study and defend its technical soundness. And they dispute Sandall’s allegation of unethical conduct, and her contention that midwife and epidemiology experts should have been selected to peer review of the study.

Wax and colleagues also provide some further information, calculating that the newborn death rate they found in their study would lead to an “excess” of one extra death per 1,333 births among babies born at home.

“[R]eflexively denying the now consistently observed increased neonatal and perinatal mortality associated with planned home birth serves no conceivable good, particularly that of families choosing home birth,” they write.