In France it's May 1. The staff want to be on vacation and if you have a complication it would be dangerous. So there's a standard distribution up the first and then in the week before a lot of induced births with thus a small dip after the 1st.
I know this because our son's due date was the 1st of May and the staff was explicit about this.
I was due Christmas day. My mom's doctor said, "I don't want to work on Christmas, so we're gonna get him out early." No talk of safety or anything else was ever discussed. I suppose there was an implicit threat that she'd get whatever unlucky random doctor was on call Xmas instead of her actual doctor.
My older sibling was a C-section, so I was going to be a C-section anyways. It just became a planned c-section due to the holiday.
I know this because our son's due date was the 1st of May and the staff was explicit about this.