Caesarean threat to natural birth

New findings cast doubt on whether women should attempt natural birth after having babies by caesarean section.

There is a risk the womb will rupture – placing the mother and baby’s lives at risk, according to a new study.

A uterine scar from a previous caesarean is the main risk factor, researchers said.

The findings contradict a study earlier this year, in the same journal, when it was suggested the risk of attempting normal birth after caesarean was minimal.

Dr Iqbal Al-Zirqi and colleagues from the University of Oslo, Norway, explored the risk among 18,794 mothers who had a previous caesarean. Of these, 11,954 attempted a vaginal birth and 6,840 had a caesarean before labour began.

Overall there were five ruptures per thousand women. The risk was eight times higher among those attempting a normal birth than planned caesarean.

The risk was highest when labour was induced, especially if prostaglandins were used. This led to a 12.6 times higher risk.

Results are published in BJOG: An International Journal of Obstetrics and Gynaecology.

The authors report that the complications following rupture of the womb included serious bleeding, need for general anaesthesia, hysterectomy, and increased infant death and brain injury due to lack of oxygen.

Dr Al-Zirqi said: "Induction should be discouraged in mothers with previous caesarean section, as it carried the highest risk, and most catastrophic consequences, of uterine rupture for both mother and neonate. If needed, mechanical induction should be used instead of medical induction by prostaglandins."

Journal editor Michael Marsh commented: "Women should be aware that although Trial of labour [attempted vaginal birth] was associated with greater risk of uterine rupture, compared to arranged repeat caesarean section, the absolute risk of uterine rupture is low.

"Further research is needed to determine the best ways of inducing labour after a previous caesarean section."

Al-Zirqi, I. et al. Uterine rupture after previous caesarean section. BJOG: An International Journal of Obstetrics and Gynaecology, published online March 24, 2010.

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