In my expierence, the best thing you can do for anal sex is just relax and have fun! Myself, I enjoy anal the best after a little of the "regular" sex as a warm up. Be sure to use plenty of lube and go as slow as you need to.
I really, seriously don't see why giving birth would have any impact on anal sex enjoyment. However, there's lots of good guides to anal sex at
www.goodvibes.com (Good Vibrations website) and
www.stockroom.com (JT's Stockroom website). Two great sites with lots of sex toys, books, and videos- and where a goodly portion of my christmas presents to myself are coming from!
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Sage knows our mythic history, King Arthur's and Sir Caradoc's
She answers hard acrostics, has a pretty taste for paradox
She quotes in elegiacs all the crimes of Heliogabalus
In conics she can floor peculiarities parabolous
-C'hi