Significance of animal studies for perinatal research

Only recently has it been possible to access human fetuses to obtain blood samples in utero, and to monitor circulatory dynamics by ultrasound. Most of our knowledge of fetal physiology and metabolism has been derived from animal studies. Using techniques of chronic implantation of intravascular catheters and specialized methods for measuring organ blood flow, cardiac output, and vascular pressures, much has been learned about normal fetal vascular physiology and its responses to stress. In addition, it has been possible to simulate abnormal morphology and to examine its effects on fetal function. Caution should be exercised in directly relating information obtained from animal studies to the human fetus. Differences in maturity at the time of birth, and in morphology, such as relative brain to body weight, must be taken into consideration.