A friend of mine stopped breastfeeding after 8 months because her job required her to travel a lot. Pumping and jetlag was just not a good fit anymore so she stopped. She weaned baby off gradually and would only pump when she felt uncomfortable, just enough to ease the engorgement. Within a month, she stopped lactating. I also read that you can seek doctor's advice regarding the use of hormones to stop lactating but it's probably best to naturally "tell" your body to stop.
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