Lulu i guess it's because at the time it provides some simple instant release.
I find that a better chiro is one that does a lot more work with the more recent 'technologies'.
'Cracking' is so old-school and considering the Chiro philosophies of working with the nervous system i don't understand how cracking was ever beneficial. Nor can i figure out how there are so many chiro's that still 'crack' and not just work on adjustment...
Anyway...

Laranna i think chiro's are fantastic in pregnancy. The only thing you might miss out on is that a lot of clinics so an 'alignment scan' kind of thing and you obviously won't be able to have the xray-type one.

ETA - and as Lulu said - see a pregnancy specialist - they have more experience dealing with the differences and changes in your shape/body etc.