there's a couple of things that might cause tightening - one being the progesterone meds, another being that, if you've not dtd for a while, you might be a bit "tighter" naturally. i know when DH is away for work, it's always a firmer fit first time around when we're together again because i think the muscles need more encouragement to stretch a bit (and i think, cos he hasnt had any for a while, his girth is a bit bigger...)

i've definitely felt different DTD every time since pg...