When I mention the subject of birth control, some women look at me as if I'm crazy. "Do you really think I'm interested in ever having sex again?" they say. But I tell them that, believe it or not, they may in fact feel like having sex again sometime soon, and they ought to be prepared. If their method of birth control is the diaphragm, they will need to be refitted, because no doubt the delivery has changed them internally. If they used to take the pill but are still nursing, I'm really not comfortable starting them back on it yet. Some hormonal methods of birth control are considered safe for nursing mothers by other doctors, but I don't think a baby ought to be ingesting these powerful chemicals through the mother's milk. I would recommend instead that women who are just taking the pill switch to a diaphragm or condom and spermicide until they've stopped nursing.
Most of my patients are afraid that intercourse will hurt, and they're right. It does hurt at first, perhaps more than it did the first time they had sex. The vagina has gone through a great ordeal, and the episiotomy stitches (if there are any) will have tightened the vagina, so that it now has less "give." A water-based lubricant such as K-Y jelly can help, especially if a woman is nursing; the hormones of nursing keep the vagina less lubricated than normal.
But the only way to completely stop sex from hurting is by getting back into the swing of it slowly-in essence, continuing to attempt to have intercourse even when it doesn't feel like the most pleasurable act in the world. One day, you will enjoy it again. (And maybe one day, the baby will actually sleep through the night, so that you and your partner can have a little uninterrupted time in bed.)