Choosing to have a baby outside a hospital comes with a slight increased risk of death to the baby in the United States but a lower likelihood of a C-section, according to a study of Oregon births published this week in the New England Journal of Medicine.

But the overall risks to the baby remained small regardless of the birth plan — there were about two deaths per 1,000 births among planned hospital births, vs. four deaths per 1,000 births planned at home or in birthing centers.

"Absolute risk of death is low in all settings — less than half of a percent. ... And in terms of that added risk, we see how someone weighs that as a personal choice," said Jonathan Snowden, an epidemiologist at Oregon Health and Science University who led the study, which examined nearly 80,000 low-risk births in Oregon during 2012 and 2013.

Women who planned to give birth outside of the hospital experienced very different kinds of birth. Far fewer women had their labor induced. A quarter of women who planned hospital births had C-sections that can add serious complications to future pregnancies — five times the rate of C-section among those who planned to give birth outside the hospital. For planned out-of-hospital births, there was an increase in some complications, such as seizures and low Apgar scores (a measure of a newborn's overall health), but the absolute risk remained low.

Giving birth at home is still a rarity — less than 1 percent of women in the United States gave birth at home in 2012. But home births have been on the rise, and it has been hard to assess how safe it is, because the numbers get conflated in confusing ways. That's because U.S. birth certificates only record where a birth took place, so women who intended to give birth at home or at a birthing center and were transferred to a hospital would be counted as hospital-based births. On the flip side, women who went into labor at home and never made it to the hospital would be counted as home births.

In 2012, Oregon added a question to its birth certificate on whether a birth was planned to take place at a hospital or elsewhere, and the change provided researchers a rare opportunity to disentangle the real health outcomes associated with both birth plans. Midwives and obstetricians praised the study.

"I think a lot of what that is going to do depends on what feels safest. What is great about this study is it gives mothers some numbers," said Melissa Cheyney, a practicing midwife in Oregon and a medical anthropologist. "Most of what has been available to women has really been driven by fear: One anecdotal case gets into the news and really sensationalizes the risk of death."

In an accompanying editorial, Michael Greene and Jeffrey Eckler, obstetricians from Massachusetts General Hospital, wrote that it's easy to see why women may consider an out-of-hospital birth: Even as hospital interventions related to birth have increased in the United States, the fetal death rate hasn't budged at major medical centers since the 1970s.

"The present data empower women to make rational decisions about their choices regarding planned place of delivery," they wrote.

Because the overall risks are low, what any woman or provider does with the information will vary, several physicians said.

"I don’t think we should go through the process of counseling and offering out-of-hospital birth to every person who comes to our practice," said Aaron Caughey, chair of the department of obstetrics and gynecology at Oregon Health and Science University and a co-author of the study. "However, we do have women who come to us who are thinking about out-of-hospital birth, and we think these data really help inform this decision."

The study excluded complicated births, including those not at full term, twins, and fetuses with abnormalities. It did not include data on maternal deaths.

"While the absolute risk of home birth remains low, this study shows what we know to be the case: It is elevated compared to hospital birth," Mark S. DeFrancesco, president of the American College of Obstetricians and Gynecologists, said in a statement. "This study underscores the importance of that being a truly informed choice."

Cheyney said she thought the study would motivate midwives to study their own practices to look for areas where they might be able to improve. Hospital providers, she said, would likely think about what they could do to reduce the rate of unnecessary interventions, such as C-sections or labor induction.

Caughey said one of the goals of the paper was to remind hospital providers about the differences between the two types of births, and what might drive women to consider different options. He stressed the importance of obstetricians understanding their patients' preferences, noting that the wrong outcome would be for women to resort to home birth simply because they don't trust the medical establishment to do what they want.

He recalled a time earlier in his career when many hospitals began scaling back offerings of vaginal birth after an earlier C-section in the mid to late 1990s. Many women, he said, decided to try the much riskier delivery outside the hospital. That, he said, is the wrong direction for things to go.

"So you take a somewhat more dangerous situation out of a hospital where it's maybe not optimal, but it's certainly not safe to do that at home," Caughey said. "That's the slippery slope, if we don't figure out ways to embrace women's preferences and doing things that women are comfortable with."