Most cases affect preterm birth infants and result from placental insufficiency and/or fetal hypoxia. The human brain undergoes gyrification during fetal and neonatal development. Prolactin promotes neurogenesis in maternal and fetal brains. Therefore, ITP is a significant cause of fetal and neonatal immune thrombocytopenia. This approach can also be used to study chromosomal aberrations in fetal and neonatal genomes. Drinking during pregnancy can result in fetal alcohol spectrum disorders. Differences in gene activation between maternal and fetal DNA can be exploited. Liver production predominates in the fetal and perinatal period; renal production predominates in adulthood. It is most active in fetal and neonatal life. Both methods offer the option of fetal and placental testing. The embryos displayed lack of fetal liver hematopoiesis. Hemoglobin variants are a part of the normal embryonic and fetal development. A break in this peripheral tolerance results in miscarriage and fetal loss. Fumarase is prevalent in both fetal and adult tissues. This test is used to determine fetal lung maturity.