Unless your doctor advices otherwise, it’s perfectly safe to have sex when you are pregnant. Your wife’s body is undergoing transformations, but sex will probably not harm the baby. However, in some cases it is necessary to refrain from sex due vaginal bleeding or premature labor and low-lying placenta. Changes may occur such as vaginal dryness, but a water-based lubricant can rectify it. Also, if it’s uncomfortable try different positions. Communication is important, discuss with your doctor and partner.