However, the authors stress that the overall risk of severe problems is small and the results are significant only for women who have previously given birth – not for first-time mums.
The relative safety of planned home births is a topic of continuous debate, but studies have so far been too small to compare severe maternal complications between planned home and planned hospital birth among low risk women.
Of all Western countries, the Netherlands has the highest percentage of home births, assisted by a primary care midwife.
So a team of Dutch researchers decided to test whether low risk women at the onset of labour with planned home birth have a higher rate of rare but severe outcomes (known as severe acute maternal morbidity or SAMM) than those with planned hospital births.
This was defined as admission to an intensive care unit, uterine rupture, eclampsia or major obstetric haemorrhage (requiring a large blood transfusion). Other adverse complications included postpartum haemorrhage (severe loss of blood after delivery) and manual removal of the placenta.
Using data from a national study into maternal morbidity and national birth registry data from 1 August 2004 to 1 August 2006, they identified over 146,000 low risk women in primary care at the onset of labour.
Results were adjusted for several factors including gestational age, maternal age, ethnic background and socioeconomic status.
Of the 146,752 women included in the study, 92,333 (63%) had a planned home birth and 54,419 (37%) a planned hospital birth.
For women having their first baby (nulliparous women), the rate of severe outcomes for a planned home birth was 2.3 per 1000 compared with 3.1 per 1000 for a planned hospital birth. The rate of postpartum haemorrhage was 43.1 per 1000 for a planned home compared with 43.3 per 1000 for a planned hospital birth.
For women who had previously given birth (parous women), the rate of severe outcomes for a planned home birth was 1 per 1000 compared with 2.3 per 1000 for a planned hospital birth. The rate of postpartum haemorrhage was 19.6 per 1000 for a planned home compared with 37.6 per 1000 for a planned hospital birth.
Adverse outcomes were less common among planned home births than among planned hospital births but differences were only statistically significant for women who had previously given birth.
The researchers emphasise that their findings may only apply to regions where midwives are well trained to assist women at home births and where facilities for transfer of care and transportation in case of emergencies are adequate.
However, they say the fact that they did not find higher rates of severe complications among planned home births "should not lead to complacency" and that "every avoidable adverse maternal outcome is one too many."
Overall, they conclude: "Low risk women in primary care with planned home birth at the onset of labour had a lower rate of severe acute maternal morbidity, postpartum haemorrhage, and manual removal of placenta than those with planned hospital birth. These differences were statistically significant for parous women."
Journal
The BMJ