Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Fetal and Placental Circulation During Labor

Physiologic Background A sufficient maternal blood supply to the placenta is of utmost importance to the fetus during pregnancy and labor. It has long been recognized that uterine contractions diminish uteroplacental blood flow. Contractions of myometrium compress the vessels traversing the uterine wall and increase intrauterine pressure, thus influencing the intervillous space pressure as well. The intrauterine pressure during labor usually ranges from 25 to 100…

Umbilical Circulation

Introduction The fetoplacental circulation, also known as umbilical circuit, with its transport of nutrients, gases, and endocrine signaling, is critical for fetal development. A long tradition of animal experiments has given us indispensable insights into its physiology. However, the introduction of ultrasound techniques enabled studies of the human version of this physiology free from the surgical trauma hampering the experimental procedures. This chapter prioritizes human data…

Mechanisms Regulating Closure of the Ductus Arteriosus

Introduction a a Portions of this chapter are reprinted from Chapter 54 in Avery’s Diseases of the Newborn, 10e. The ductus arteriosus represents a persistence of the terminal portion of the sixth branchial arch. During fetal life, the ductus arteriosus serves to divert blood away from the fluid-filled lungs toward the descending aorta and placenta. After birth, constriction of the ductus arteriosus and obliteration of its…

Nutritional and Environmental Effects on the Fetal Circulation

Acknowledgments Preparation of this chapter was supported by grants from the British Heart Foundation, the Biotechnology and Biological Sciences Research Council, and Gerald Kerkut Trust. Introduction The fetus depends on its cardiovascular system for growth and development. Vascular growth is closely linked to tissue growth, and the fetal heart must develop in relation to the venous return (preload), primarily from the umbilical vein, and the similar…

Regulation of Cardiovascular Function During Fetal and Newborn Life

Introduction The regulation of cardiovascular function in the fetal and newborn periods is mediated through interacting neural, endocrine, and metabolic mechanisms acting at central, systemic, and local levels. The role of the central nervous system, in particular, is critical for cardiovascular homeostasis, including maintenance of blood pressure within normal limits. , Sympathetic outflow to the heart and blood vessels is continuously modulated by an array of…

Physiology of Congenital Heart Disease in the Neonate

† Deceased. Introduction Understanding the cardiovascular physiology of a neonate with a cardiac malformation requires consideration of many factors, including myocardial systolic and diastolic function; intravascular volume; cardiac and vascular transmural pressures; the pattern of intracardiac blood flow with shunting lesions; and arterial and pulmonary venous oxygen (O 2 ) content. Any description taking into account only these variables would be incomplete, however, because cardiac lesions…

Development of the Gastrointestinal Circulation in the Fetus and Newborn

Introduction The intestine is a complex series of tissues, each with a specific role in digestion and excretion. For a mature intestine to function properly, it must protect its component cells from other organisms, including bacteria, viruses, and parasites, as well as from toxic substances. In addition, the intestine, in partnership with the liver and pancreas, disassembles potential nutrients and presents them (sugars, fats, proteins, vitamins,…

Developmental Biology of the Pulmonary Vasculature

Introduction This chapter discusses the changing morphology of the developing fetal, neonatal, and postnatal pulmonary vascular bed. Studies have focused on structural and functional alterations in endothelial cells during postnatal development and have addressed the phenotypic heterogeneity of the vascular smooth muscle cells (SMCs) in the perinatal period. There are new insights into mechanisms regulating endothelial migration and angiogenesis, SMC proliferation, hypertrophy, and migration. These studies…

Developmental Electrophysiology in the Fetus and Neonate

Introduction In this chapter, the physiology of both impulse formation and conduction in the developing heart is discussed. Significant developmental or age-related changes in the ionic currents are responsible for the generation of cardiac action potential, as well as changes in the microscopic and macroscopic anatomic and neural substrates that govern the physiology of cardiac depolarization and repolarization during health and disease. Recently, important breakthroughs in…

Cardiovascular Development

Introduction The formation and subsequent development of the heart is a complex process that involves multiple cell populations, a plethora of molecular regulatory mechanisms, and intrinsic, complicated spatiotemporal remodeling events. When all the developmental steps have been properly concluded, the fully septated four-chambered heart will beat a few billion times during the individual’s life span, thereby sustaining three interdependent blood circulations (systemic, pulmonary, and coronary). Although…

Physiologic Development of the Skin

Introduction Human skin is a complex structure with unusual functional diversity. , Topologically, the skin is continuous with the lung and intestinal epithelia. The lung and gut are generally viewed as exchange surfaces for gases and nutrients; the skin is more commonly considered a barrier. , , The concept of an integumental barrier emphasizes the role of the skin as a protective boundary between an organism…

Structure and Development of the Skin and Cutaneous Appendages

Acknowledgment The editors wish to thank authors David H. Chu and Cynthia A. Loomis for their excellent contribution to this text in the fifth edition. This chapter has been reproduced here in the sixth edition essentially unchanged. Introduction Skin is a complex organ that comprises many different cells and cell types; it forms a critical physical barrier that protects the body and maintains fluid homeostasis, temperature…

Temperature Control in Newborn Infants

Acknowledgment Based on a previous chapter by Karl Schulze, MD. Introduction This chapter is an updated revision of Dr. Kurt Brück’s comprehensive treatise on neonatal thermal regulation presented in earlier editions; it is not an original synthesis by the current author. Dr. Brück remains the senior contributor despite his death in 1995 in recognition of and with immense admiration for his many contributions to our understanding…

Placental Transfer and Fetal Requirements of Amino Acids

Introduction Placental uptake, metabolism, and transfer of amino acids to the fetus are critical for both placental and fetal development and growth to produce a successful pregnancy. Placental amino acid transfer is mediated by active transport and is performed by over 20 distinct amino acid transport systems that are present on the maternal facing apical, microvillous, and fetal facing, basal plasma membranes of the placental syncytiotrophoblast.…

General Concepts of Protein Metabolism

Introduction This chapter describes the methods used to evaluate dynamic changes in protein metabolism in the newborn infant. Throughout life, proteins not only form the key structural components of cells but also have key physiologic roles as, for example, transporters, immune mediators, receptor proteins, enzymes, and hormones. In a consideration of the relevant kinetics, the fundamental point of interest is that amino acids—the building blocks of…

Cell Glucose Transport and Glucose Handling During Fetal and Neonatal Development

Introduction Glucose is the primary substrate for the growing and developing fetus, and in normal human pregnancies there is little fetal gluconeogenesis. Glucose is required by most cells for oxidative and nonoxidative adenosine triphosphate (ATP) production and serves as a precursor for other carbon-containing compounds. It is the primary fuel used for several specialized cells and is the major fuel used by the brain. Its storage…

Role of Glucoregulatory Hormones in Hepatic Glucose Metabolism During the Perinatal Period

Acknowledgments The authors wish to thank Richard M. Cowett, MD, for his valuable contributions to this chapter in the fifth edition. Introduction After birth, the newborn must rapidly become capable of balancing glucose deficiency with glucose excess to maintain euglycemia. Development of carbohydrate homeostasis is essential to avoid both hypoglycemia and hyperglycemia, to which neonates (especially the sick, preterm, and growth restricted) are vulnerable. Both hypoglycemia…

Oxygen Consumption and General Carbohydrate Metabolism of the Fetus

Introduction This chapter reviews a number of factors that are involved in control of fetal metabolism, with reference to relationships between fetal energy balance and substrate uptake during the last trimester. This information relies heavily upon research data obtained from a variety of experiments in animals as well as some theoretical considerations. Data from human studies are now also becoming more available than in previous years…

Glucose Metabolism in the Fetus and Newborn, and Methods for Its Investigation

Acknowledgments The authors thank Satish C. Kalhan, MD, as we adapted portions of the text and several figures from his version of this chapter in the prior edition. Dr. Sarah Wernimont was supported by grant T32 DK112751. Dr. Andrew Norris and the previously unpublished data shown in this chapter were supported by grants R01 DK115791, R24 DK96518, and R01 DK097820. Introduction Glucose metabolism has been studied…

Long-Chain Polyunsaturated Fatty Acids in Neurodevelopment

Introduction The brain and retina contain large quantities of long-chain (20 and 22 carbon) n -3 and n -6 polyunsaturated fatty acids (LCPUFAs), particularly docosahexaenoic acid (DHA; 22:6 n -3) and arachidonic acid (AA; 20:4 n -6). , During the last intrauterine trimester , and the first 18 months of postnatal life, DHA and AA accumulate in neural tissue at a high rate, supported by selective…