My wife was highly oversexed during her pregnancies. Man, she was horny. Early on we would use any position until the belly really began to swell. After that we used many positions, including my favourite, doggy style.
I hear of a couple folks who stopped having sex while pregnant, man they are missing the best sex of their lives. With one child, at 7 months my wife developed a wee leak in her amniotic sac and the doctor ordered no intercourse, bathing, of any other activity that might cause infection. I probably got more head, as did my wife, in that short period of life than any other full year combined.
