Things should pick up once you are past the first trimester. The second trimester is often marked by a resurging libido. Your desire may wane again in the third trimester, as impending labor and delivery, and your belly loom large. By this point, some women just simply feel unattractive. The sex drive of your partner may actually increase.
Most men find their pregnant partner truly attractive.
But your partner's desire may be dampened by his concern for your health and your baby's health, apprehension about the burdens of becoming a father, fear that sex can hurt the baby, or even self consciousness about making love in the presence of their unborn child. Sex is not harmful for your baby, in fact in most cases, the motion of having sex will rock your little one off to sleep. You won't hurt the baby by making love, even with your partner on top. The thick mucus plug that seals the cervix helps guard against infection. The amniotic sac and the strong muscles of the uterus also protect your baby.