Why do Chinese people say 一孕傻三年？ Just the other day, I heard this '一孕傻三年'. Does anyone have an inkling as to why Chinese people think this?
Since I don't have enough reputation to comment

It's not only in Chinese culture, it's called "baby brain" http://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/baby-brain/faq-20057896