The hazards of men smoking and drinking on pregnancy preparation include the possibility of infertility and poor embryo quality. 1. Infertility: Frequent smoking will cause constriction of penile arteries, which will not only affect erectile function, but also lead to a decrease in the number of spermatozoa, a decrease in the quality of spermatozoa, an increase in deformed spermatozoa, and a decrease in male fertility. Drinking a lot of alcohol will result in loss of libido and lower quality of sperm, leading to male infertility. 2. Poor embryo quality: Smoking and drinking will affect the quality of sperm, which may lead to poor embryo quality if you get pregnant. Miscarriage and embryonic arrest will occur during the development of the embryo, and the fetus may be born with stunted growth and mental retardation. Men should not smoke and drink during the preparation for pregnancy, and should quit smoking and drinking for at least three months before preparing for pregnancy.