Don't bother, denu. I'm sure there's a correlation. As in: Developed countries are more likely to allow abortion (with the exception for Ireland, of course). And, developing goes hand in hand with sinking birth rates, although usually with a time laps of one generation.
So, sorry, I worded that wrong in my post above. There is a correlation. However, legalization of abortion isn't the cause of sinking birth rates but both are caused by development.