Knowledge of respiratory gas exchange across the human placenta depends on integrating observations in pregnant patients with experimental findings in laboratory animals. The evidence in laboratory animals consists of a fairly comprehensive set of data in sheep, with chronically implanted…
Blood Flow Patterns and Oxygen Delivery In the mammalian adult, oxygenation occurs in the lungs, and oxygenated blood returns via the pulmonary veins to the left side of the heart to be ejected by the left ventricle into the systemic…
Sufficient intake of nutrients during pregnancy is essential to meet the demands of fetal growth and development as well as maternal physiologic adaptations to pregnancy. The nutritional status of pregnant women in the United States is suboptimal , owing to…
Universal breastfeeding is recommended by the American College of Obstetricians and Gynecologists (ACOG), the World Health Organization (WHO), the United Nations Children’s Fund (UNICEF), the American Academy of Pediatrics (AAP), and the Special Supplemental Nutrition Program for Women, Infants, and…
The concept of the fetus, the placenta, and the mother as a functional unit originated in the 1950s. More recent is the recognition that the placenta itself is an endocrine organ capable of synthesizing virtually every hormone, growth factor, and…
Profound physiologic changes occur in the cardiovascular, respiratory, and renal systems during pregnancy. These adaptations begin soon after conception and continue as gestation advances, yet most are almost completely reversed within weeks to months after delivery. These physiologic adaptations are…
Pregnancy as an Allograft Occurrences of recurrent abortion, preeclampsia, or hemolytic diseases of the newborn raise the rhetorical question, “Why did your mother reject you?” However, when considering the complexity of maternal-fetal immune interactions and the vast number of successful…
Preterm Birth Syndrome: Phenotypic Classification In humans, singleton pregnancies last on average 280 days (40 weeks) from the first day of the last menstrual period to the estimated date of delivery. Preterm birth (PTB) is defined as birth between 20…
Labor is the physiologic process by which the products of conception are passed from the uterus to the outside world, and it is common to all mammalian viviparous species. Considerable evidence suggests that the fetoplacental unit primarily controls the timing…
The incidence of multiple births has increased dramatically over the past 5 decades. In the United States, twin birth rates increased almost twofold between 1971 and 2014. This sharp increase in twin births has been linked to two related factors:…