Does the first three months of pregnancy have an effect on the fetus

Cohabitation during the first trimester of pregnancy increases the likelihood of miscarriage and is detrimental to the fetus. Cohabitation during the first trimester of pregnancy, when the embryo is still unstable, can stimulate uterine smooth muscle contraction, resulting in threatened abortion or miscarriage. It is generally recommended that cohabitation is prohibited during the first trimester of pregnancy.