Does birth weight increase with each successive child?

A Twitter discussion about casheroo’s ever-growing jellybean got me wondering about this. Dr_C says it’s a myth and, since he’s delivered hundreds of babies, I believe him. But the myth holds true in my personal experience. I’m sure if I’d taken more than an hour to search, I would’ve been able to find someone I know who had multiple children whose birth weight didn’t increase with each child. But I didn’t, so I couldn’t. The only instance of birth weight decreasing in my group of family and friends is my sister’s fifth baby, who was slightly smaller than her fourth. Good thing for her; if he wasn’t, she would’ve had an 11-pound baby. Ow…

Actually, I guess there are two instances. The other was when one of my mother’s sisters was born prematurely and nearly died. If she’d gone to full term, she probably would’ve fit right into the increasing pattern, though.

What is your experience with birth weights? You and your siblings, your friends’ kids, your own kids, whatever. Do the people you know support or debunk the myth?