My babe is due March 9. I have this agreement at work: the official last day is two weeks before expected due date. Feb 20 was the deadline for tidying up/writing instructions for the next people to take over smoothly. But I will continue coming in for as long as I can. I'm just not expected in the office every day, and may request shorter hours. I told them that I would definitely like to work the two busiest days, Monday and Thursday.
My coworkers either have very large or young families, so they've been wonderfully accommodating.