Yes, in most cases it is perfectly safe to have sex while you are pregnant unless your water has broken or your doctor has instructed you otherwise.  You might find that you have to vary positions as the pregancy advances.  Lying side-by-side with your partner behind you (as if spooning) works well for many couples, especially late in pregnancy.  Experiment and see what works for you.  Occasionally, there are complications that require that a patient avoid having sex for all or part of the pregnancy.  These can include low lying placenta, placenta previa, incompetent cervix, history of preterm labor, or if you are expecting more than one baby.  If you have any questions about whether or not you have a complication that precludes you from having sex, discuss it with your physician.

Many women wonder if having intercourse hurts the baby.  The answer is no.  Your partner's penis does not come in contact with the baby during intercourse.  The mucus plug seals the cervix and the baby is surrounded and protected by amniotic fluid and the strong muscles of the uterus.