Home Birth Reference Site

Birthplace 2011 Study

The Birthplace 2011 study provided valuable information on homebirth safety, helping women to make an informed decision.

Overall, the researchers found that "as a whole, home births are as safe as ones in medical settings." But first babies were shown as a group with worse outcomes compared to the rest. The increased risk was small overall, but was clearly there.

The NHS News report on the study says:

The overall rate of negative outcomes (a composite of outcomes of death or serious complications) was 4.3 per 1000 births (95% confidence interval [CI] 3.3 to 5.5) and there was no difference between non-obstetric unit settings compared with obstetric units. This indicates that as a whole, home births are as safe as ones in medical settings.

"The researchers then looked only at women who were going through their first pregnancy. They found that women having their first birth at home had a greater chance of complications leading to injury in the child than women who had planned to go to an obstetric unit in a hospital. This risk was almost doubled (odds ratio [OR] 1.75, 95% CI 1.07 to 2.86).
Furthermore, when the sample was restricted to women who had no complicating conditions at the start of labour, there was almost a three-times greater risk for women with planned home births than for women having planned hospital births (OR 2.80, 95% CI 1.59 to 4.92). There was no difference in the rates of such complications in either type of midwife-led unit compared with hospital units.

An important point to note is that even though the risk associated with home births seems greatly elevated in women going through their first pregnancy, the absolute risks were still relatively low. To put this into context, they occurred in 39 of the 4,488 women who delivered their first child at home, and 36 of the 4,063 women who delivered their first child at home without complicating conditions at the start of labour."

(my emphasis)

The absolute numbers were so small that there wasn't much to tell us why there was an increased risk for first-time mothers - but still, I think it's fair to say it tells us that there is a price to pay for the improved outcomes (more normal birth, better maternal outcomes). It's all about balancing different risks. The Birthplace study looked at a very specific set of adverse outcomes - death, brain damage, meconium aspiration syndrome, and a specific list of injuries including brachial plexus injury, which is commonly associated with shoulder dystocia. There were 36 babies out of 4,063 who suffered an 'adverse outcome' of this kind. These included 6 stillbirths and early neonatal deaths out of 4,568 low-risk first-time mothers planning a homebirth, and 5 stillbirths/early neonatal deaths out of 10,593 similar primiparas planning birth in an obstetric unit (the denominators keep varying according to what category you're looking at, but you get the gist).

There is a good analysis of this from someone with a background in statistics on the 'Statistical Epidemiology' blog. Don't be put off by the title - it's surprisingly readable.

Actually 45% of first-time mothers transferred (not very different from previous UK studies), so many of them will, presumably, have been in hospital already when the problem happened. It's a shame the study didn't include data on this; I would like to know, for instance, how many problems occurred when babies were born at home in unexpectedly poor condition, and how many were transferred in labour when the midwife suspected something was amiss. There is a huge difference between, say, being at home with a baby that doesn't want to breathe, and being in hospital after transferring due to a long labour, and then having labour augmented and the baby going into distress.

I think one way of looking at it is - planning a homebirth gives the first-time mother a higher chance of having the best possible outcome, ie straightforward birth, everyone healthy, no surgical or assisted deliveries, which have implications for the mother's health in particular. But the price of that is a very slightly higher chance of the worst possible outcome.

The Statistical Epidemiology article says:

"But what are the absolute risks? Among nulliparous planned homebirths, there were 9.5 primary outcomes per 1000 births; for planned obstetric births there were 5.3 per 1000. So the absolute risk difference is about 4 events per 1000 births"

Is that price worth paying? It will be different for every family. If you are panicked about hospitals or are very worried about losing control then perhaps the 'cost' of planning a hospital birth for you will be higher, because a bad experience there may leave you with a tough start to motherhood. Perhaps it is important to you to have a large family, and therefore a caesarean section would be more risky for you than for others - because it increases the risk of secondary infertility and increases the risk of stillbirth in future pregnancies. Statistics can help to inform our decisions, but they can't usually give us the whole picture of our personal risk profile.

What has not been discussed so widely is the fairly stunning data in favour of birth at home or in a midwifery unit for second and subsequent babies, for low-risk women. The 'rapid responses' to the study in the British Medical Journal contain some interesting comments from obstetricians on this, about how they can try to improve care in obstetric units.


Birthplace 2011 study

NHS News report on the Birthplace 2011 study

'Statistical Epidemiology' blog - a good analysis of the study from someone with a background in statistics. Don't be put off by the title - it's surprisingly readable.

Maternal Link blog on the Birthplace 2011 study

British Medical Journal 'rapid responses' to the study contain some interesting comments from obstetricians and midwives.

This page updated 14 July 2012


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