I have no professional input; however, I had preterm labour with my first baby (gave birth at 38 weeks but was on/off bed rest for preterm contractions and on meds for it at 20 weeks onwards).  I became pregnant with my second when he was two and I worried about having to wean.  I had a normal pregnancy with no complications and did for my subsequent pregnancies as well.  I've always recommended moms find out their doctors concern before weaning and often suggest they ask about whether having an orgasm is safe (it's not just the prostaglandins in semen that could be problematic, but the oxytocin release during female orgasm that could also trigger early labour).  As the general rule, anecdotally, is that if sex/orgasm is not considered risky by the OB then breastfeeding should not be either.

Good luck to your friend. 

Margo

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