Typically, women will experience a diminished sex drive during their first trimester. In part they may feel a little bit ill with nausea. Typically, the sex drive returns in the second trimester as you start to feel better. Sex is certainly safe during pregnancy and it leads to increased feelings of self esteem and love. Although the frequency of sex between partners may decrease between the second and third trimesters, it can still be enjoyed on a regular basis. During the last trimester it is usually easier for the woman to be on top.