Pregnancy and Periods

I will be crossposting this to multiple different subs. This is more of a postpartum question than anything else, but I figured this would be one of the best places to start (r/breastfeeding) as it is quite a large community of moms, specifically post-birth. *Question: If you were someone who lived with women throughout your entire pregnancy (mother, sister, wife, girlfriend, etc.), did their menstrual cycle line up/sync with the time you gave birth?* (I am trying to connect some dots with my prolactin levels, breastfeeding, and my sister leaving after a year) Thanks!