Developmental toxicity studies are preclinical studies that are conducted to evaluate the potential adverse effects of a substance on prenatal development. These studies are typically conducted in laboratory animals, such as rats, mice, or rabbits, to assess the safety of a drug or other substance before testing in humans.

The primary objective of developmental toxicity studies is to identify any potential adverse effects of the substance on the developing fetus, including embryonic or fetal death, growth retardation, malformations, and functional deficits. These studies can be further divided into two categories based on the timing of exposure:

1. Teratology studies: These studies are conducted to evaluate the potential effects of the substance on fetal development during the organogenesis period, which occurs during the first trimester of pregnancy in humans. The studies involve administering the substance to pregnant animals during this period and evaluating the potential effects on fetal growth, development, and viability.
2. Perinatal/postnatal studies: These studies are conducted to evaluate the potential effects of the substance on offspring after birth. The studies involve administering the substance to pregnant animals and evaluating the growth, development, and behavior of the offspring after birth.

Developmental toxicity studies typically involve the use of a range of doses of the substance and the evaluation of multiple endpoints, such as fetal body weight, skeletal development, and histopathological examination of fetal tissues.

The results of developmental toxicity studies can help inform decisions about the safety of the substance for use in humans, particularly in pregnant women. These studies are an essential part of the preclinical safety assessment of drugs and other substances, and can help identify potential risks to prenatal development that may need further investigation in clinical trials.