Progesterone is a hormone normally secreted by the body in pregnancy is required for the viability of the pregnancy. High dose progesterone is known to cause neural tube defects (NTDs) in certain animals.In humans, exogenous high dose progesterone may be administered during in-vitro fertilization and in Intracytoplasmic sperm injection treatment. Studies on the teratogenic effects of progesterone have dealt mostly with the possible masculinising effect on the female fetus. Other abnormalities that have been described with the use of progesterone are cardiac malformations, the effects on the central nervous system, like neural tube defects and development of Amelia. Around the world, there are hundreds of thousands of pregnancies affected each year by NTDs, with some fetal demise through spontaneous or induced losses. Based on animal studies, epidemiologic studies and intervention trials, maternal folic acid (vitamin B9) is known to be protective for NTDs, primarily spina bifida and anencephalus. The purpose of the present study was to describe the effect of HDP alone, or in combination with folic acid, on occurrence of NTDs in chick embryo.