I’ve done no research, but I highly doubt it.

We shouldn’t expect any change in people’s activity before the 11th, because it was a surprise. I imagine there were quite a few people who weren’t “in the mood” on the 11th, but how long would that last? Possibly a while in NYC, but I’m betting most of the people Midwest got their libido back in a day or two.

Considering that pregnancy isn’t an exact science, and that a child conceived a week before or after 9-11 could have born exactly 9 months after 9-11, I don’t think we’d see a major drop in births around that time. Maybe a little, but probably nothing significant.