[zenpaul]

There is a noticeable Christmas effect, with birthdays down then and up 9 months later.

I wonder if this has changed in more recent years with changes in demographics.

[kijin]

Interestingly, Boxing Day (Dec 26) has noticeably fewer births than any day except Feb 29. I wonder if that's related to Christmas as well.

[molmalo]

I bet that scheduled c-sections play a role in that...