Home birth is more dangerous. Discuss.

How dangerous is too dangerous?

We don’t prohibit all dangerous behavior, or even behavior that endangers others, including people’s own children.

Question: Is the limit of acceptable risks to which we may subject our own children determined by absolute risks or relative risks?

Case for consideration: Home birth.

Let’s say planning to have your birth at home doubles the risk of some serious complications. Does that mean no one should do it, or be allowed to do it? Other policy options: do nothing, discourage home birth, promote it, regulate it, or educate people about the risks and let them do what they want.

Here is the most recent result from a large study reported on the New York Times Well blog, which looks to me like it was done properly, from the American Journal of Obstetrics & Gynecology. Researchers analyzed about 2 million birth records of live, term (37-43 weeks), singleton, vertex (head-first) births, including 12,000 planned home births (that is, not including those where the home birth was accidental). They also excluded those at freestanding birthing centers.

The planned-home birth mothers were generally relatively privileged, more likely to be White and non-Hispanic, college-educated, married, and not having their first child. However, they were also more likely to be older than 34 and to have waited to see a doctor until their second trimester.

On three measures of birth outcomes, the home-birth infants were more likely to have bad results: low Apgar scores and neonatal seizures. Apgar is the standard for measuring an infant’s wellbeing within 5 minutes of birth, assessing breathing, heart rate, muscle tone, reflex irritability and circulation (blue skin). With up to 2 points on each indicator, the maximum score is 10, but 7 or more is considered normal and under 4 is serious trouble. Low scores are usually caused by some difficulty in the birth process, and babies with low scores usually require medical attention. The score is a good indicator of risk for infant mortality.

These are the unadjusted low-Apgar and seizure rates:

These are big differences considering the home birth mothers are usually healthier. In the subsequent analysis, the researchers controlled for parity, maternal age, race/ethnicity, education, gestational age at delivery, number of prenatal care visits, cigarette smoking during pregnancy, and medical/obstetric conditions. With those controls, the odds ratios were 1.9 for Apgar<4, 2.4 for Apgar<7, and 3.1 for seizures. Pretty big effects.

Two years  ago I wrote about a British study that found much higher rates of birth complications among home births when the mother was delivering her first child. This is my chart for their findings:

Again, those were the unadjusted rates, but the disparities held with a variety of important controls.

These birth complication rates are low by world historical standards. In New Delhi, India, in the 1980s 10% of 5-minute-olds had Apgar scores of 3 or less. So that’s many-times worse than American home births. On the other hand, a number of big European countries (Germany, France, Italy) have Apgar<7 rates of 1% or less, which is much better.

A large proportional increase on a low risk for a high-consequence event (like nuclear meltdown) can be very serious. A large absolute risk of a common low-consequence event (like having a hangover) can be completely acceptable. Birth complications are somewhere in between. But where?

Seems like a good topic for discussion, and having some real numbers helps. Let me know what you decide.

Study shows home births are not as safe. So?

There’s an interesting example of how to interpret scientific results — and draw policy implications from them — from the world of birth practices and safety.

The subject of the debate is a major new study from the British Medical Journal. The study followed more than 60,000 women in England with uncomplicated pregnancies, excluding those who had planned caesarean sections and caesarean sections before the start of labor. They compared the number of bad outcomes — from death to broken clavicles — for women depending on where they had their births.

One comparison stands out in the results. From the abstract: “For nulliparous women [those having their first birth], the odds of the primary outcome [that is, any of the negative events] were higher for planned home births” than among those planned for delivery in obstetric units. That is, the home births had higher rates of negative events. The difference is large. Here’s a figure to illustrate:

The error bars show 95% confidence intervals, so you can see the difference between home births and obstetric-unit births is statistically significant at that level. These are the raw comparisons, but the home-versus-obstetric comparison was unchanged when the analysts controlled for age, ethnicity, understanding of English, marital or partner status, body mass index, “deprivation score,” previous pregnancies, and weeks of gestation. Further, by restricting the comparison to uncomplicated pregnancies and excluded all but last-minute c-sections, it seems to be a very strong result.

But what to make of it?

In their conclusion, the authors write:

Our results support a policy of offering healthy nulliparous and multiparous women with low risk pregnancies a choice of birth setting. Adverse perinatal outcomes are uncommon in all settings, while interventions during labour and birth are much less common for births planned in non-obstetric unit settings. For nulliparous women, there is some evidence that planning birth at home is associated with a higher risk of an adverse perinatal outcome.

But in what way do the results “support a policy”? The “higher risks” they found for planned home births are still “uncommon,” by comparison, with those in poor countries, for example. But the home birth risk is 2.7-times greater.

The Skeptical OB, who is a reliable proponent of modern medical births, titled her post, “It’s official: homebirth increases the risk of death.” She added some tables from the supplemental material, showing the type of negative events and conditions that occurred. Her conclusion:

“In other words, any way you choose to look at it, no matter how carefully you slice and dice the data, there is simply no getting around the fact that homebirth increases the risk of perinatal death and brain damage.”

I guess the policy options might include include whether home births should be encouraged, more regulated, covered by public and/or private health insurance, banned, penalized or (further) stigmatized.

Home birth seems safer than letting children ride around unrestrained in the back of pickup trucks, which is legal in North Carolina — as long as they’re engaged in agricultural labor. On the other hand, we have helmet laws for kids on bicycles in many places. And if a child is injured in either situation, hopefully an ambulance would take them to the hospital even if the accident were preventable.

In other words, I don’t think policy questions can be resolved by a comparison of risks, however rigorous.