Why are multiparous women more at risk of uterine rupture?

A multiparous woman is one who has previously given birth to at least one baby after 28 weeks of gestation. The gestational age is significant, because by 28 weeks the fetus will have reached a substantial size and weight, so the multiparous woman's uterus will already have been stretched. One result of this stretching is that the delivery is expected to be easier in subsequent pregnancies – which is, indeed, usually the case. Despite this fact, multiparous women are more likely than primiparous (first-time) mothers to experience uterine rupture if their labour is obstructed.

Can you suggest a reason for this unexpected finding?

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One reason is that first-time mothers do not have a previous history of complicated delivery, whereas a woman who has given birth before may have already had complications which caused scarring of the uterus or other parts of the birth canal. Such scarring is a risk factor for a ruptured uterus.

Last modified: Friday, 11 July 2014, 12:00 PM