This is a very common question asked by couples who are expecting their first child. This is a very valid query, as there is not a lot of information about this important subject. In general it is quite safe to have sex during pregnancy.
Though there is not enough evidence to prove that restriction of sex for those women who are at a risk of preterm labor or face a complication like placenta previa, during their pregnancy is totally necessary, it is recommended that they avoid having sex during their term. Which is a sensible course of action just to be on the safe side.
In normal or low risk pregnancies, the decision to have sexual intercourse is a decision which should be be taken by the expectant mother. She should be comfortable with the idea and feel physically upto it. Stop the moment she starts to feel uncomfortable about it. It is important for the man to be understanding and supportive of her feelings even if having sex is safe.
Due to the hormonal and physical changes that a pregnant woman goes through, it is even more important for her partner to reassure her about her looks and attractiveness . This will not only make her feel much better about herself but also encourage her to be more intimate.
In any case it is always recommended that you clear all your doubts about having sex during pregnancy with your doctor. And remember if in doubt or at the first sign of discomfort, discontinue and abstain from sex until you consult with your doctor and follow his /her recommendations.