One sister finished training right before her wedding, but the other is doing a fellowship now. Her husband has a more flexible job, so they travel together to seminars and conferences. Most fellowships are less time-consuming and more flexible than residencies though (internship is the first year of residency and often the most intense).
I do know of women who’ve married during medical school or residency and had babies during those years. Generally I’d say that they have supportive spouses and/ or support from family and friends–just like men who start families during med school and residency do.