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Two or three membrane sweeps are offered to overdue mothers in weeks 40 and 41 to start labour. Is it advisable to skip the first membrane sweep at week 40 and simply wait for a week, or does this decrease the probability of “spontaneous labour”, therefore leading to a higher chance of other means of induction?


Most of the literature I found looks at the efficacy of sweeps (vs. no sweep at all). They find that yes, sweeps are useful for bringing on labour.

Dutch study utilising repeated membrane sweeps

Cochrane Review

But I did find an RCT that indicated that 40-week sweeps increased the effectiveness of 41-week sweeps:

one week later (at 39 weeks). However, nulliparous women had previously seemed to benefit most from sweeping of the membrane.
We think that weekly sweeping puts women in a pre-labour situation where irregular contractions have a cervical ripening effect. This may explain why our women assigned to sweeping of the membranes had a higher Bishop score on admission and a lower induction rate. Multiple sweeping may therefore be more effective that single sweeping.
This latter finding is in line with a recent randomised trial where women allocated to sweeping underwent a single sweep at 38 to 40 weeks of gestation and where no significant difference was found in the proportions of women who started labour spontaneously within seven days or before 41 weeks. However, a single sweep performed post-term was effective in promoting spontaneous labour. The timing of sweeping of the membranes may therefore be important. Future trials should aim at elucidating the optimum gestational age at which sweeping of the membranes should start.

So I think according to this study single sweeps before 41+0 are less effective than single sweeps after, but these authors seem to think that the pre-41 week sweeps may improve efficacy of the post-41 sweep. I'm curious if others draw the same conclusion.

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    thanks @LangLangC - I see what you mean. Edited accordingly. – the_scheining Oct 24 '18 at 14:24
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    The wording is now rather confusing. I would ask it more along the lines of "if a first membrane sweep is ineffective in promoting labor, is there evidence for doing a second membrane sweep? If so, at what interval?" and provide what you'd found so far in attempting to answer the question yourself. – DoctorWhom Oct 25 '18 at 3:47
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    Yes, the wording must be confusing, because that's not my question at all. My question is the reverse: Is there usefulness in the first membrane sweep (at 40 weeks) if a woman is going to get a membrane sweep at 41 weeks. – the_scheining Oct 25 '18 at 7:48
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    I have heavily reworked your question to make it clear, and to make it about what you actually want to know. Please do note that this academic question is in my eyes a valid one, but for you personally to draw conclusions, please discuss it with your midwife or doctor. – Narusan Oct 25 '18 at 9:30
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    Thanks @Narusan. I've edited further. As I explained above, my question is not whether the 'second' membrane sweep is useful if the first fails. (It clearly is.) My question is whether the 40 week membrane sweep is useful at all in light of the opportunity to do a sweep at 41 weeks. – the_scheining Oct 26 '18 at 13:52

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