During which period of development is the unborn baby most at risk of developing a structural defect due to the effects of a teratogen

Teratogens are agents or factors that causes malformation of an embryo they include alcohol, cigar smoke, drugs, maternal stress and paternal age. At the embryonic period the unborn baby is at a very high risk of developing structural defects ddue to the effects of teratogens. Teratogens may lead to abnormal development in muscles, tendons and bones.