The prenatal period begins with the formation of the embryo Embryo The entity of a developing mammal, generally from the cleavage of a zygote to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the fetus. Fertilization and First Week and continues through the development of the fetus, terminating with birth. Neonatal physiology during prenatal life differs significantly from that during postnatal life. Before birth, nutrient, gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange, and elimination Elimination The initial damage and destruction of tumor cells by innate and adaptive immunity. Completion of the phase means no cancer growth. Cancer Immunotherapy of waste products occur via the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity. The fetus receives oxygenated, nutrient-rich blood via the umbilical vein, and deoxygenated blood is returned to the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity for removal of waste via the umbilical arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology. The 3 shunts that help redirect the fetal circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment are the ductus venosus Ductus venosus Development of the Heart, foramen ovale Foramen ovale An opening in the wall between the right and the left upper chambers (heart atria) of a fetal heart. Oval foramen normally closes soon after birth; when it fails to close the condition is called patent oval foramen. Patent Foramen Ovale, and ductus arteriosus Ductus arteriosus A fetal blood vessel connecting the pulmonary artery with the descending aorta. Patent Ductus Arteriosus (PDA). These shunts close after birth, leaving behind vestigial remnants. Postnatally, the fetal circulatory system and organ systems adapt to the extrauterine environment. Placental blood supply is cut off, causing the neonate Neonate An infant during the first 28 days after birth. Physical Examination of the Newborn to make adaptive changes.
Last updated: 10 May, 2022
Gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care in weeks | Characteristics |
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Weeks 3–4 |
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Weeks 5–8 |
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Weeks 9–12 |
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Weeks 13–16 |
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Weeks 17–20 |
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Weeks 21–24 |
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Weeks 25–28 |
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Weeks 29–32 |
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Weeks 33–36 |
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Weeks 37–40 |
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Fetal
circulation
Circulation
The movement of the blood as it is pumped through the cardiovascular system.
ABCDE Assessment:
Oxygenated blood from the umbilical vein drains into the
inferior vena cava
Inferior vena cava
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy (
IVC
IVC
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy), which also collects the blood from the organs and lower portion of the body, causing the blood to become slightly deoxygenated.
Fetal
circulation
Circulation
The movement of the blood as it is pumped through the cardiovascular system.
ABCDE Assessment in the heart:
Blood from the
inferior vena cava
Inferior vena cava
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy (
IVC
IVC
The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs.
Mediastinum and Great Vessels: Anatomy) pushes the valve of the
foramen ovale
Foramen ovale
An opening in the wall between the right and the left upper chambers (heart atria) of a fetal heart. Oval foramen normally closes soon after birth; when it fails to close the condition is called patent oval foramen.
Patent Foramen Ovale and flows into the left side of the heart, where it mixes in the left atrium (LA) with deoxygenated blood from the
pulmonary veins
Pulmonary veins
The veins that return the oxygenated blood from the lungs to the left atrium of the heart.
Lungs: Anatomy. The blood leaves the heart through the
aorta
Aorta
The main trunk of the systemic arteries.
Mediastinum and Great Vessels: Anatomy and flows to the iliac
arteries
Arteries
Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles.
Arteries: Histology, which are connected to the
placenta
Placenta
A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones).
Placenta, Umbilical Cord, and Amniotic Cavity by the umbilical
arteries
Arteries
Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles.
Arteries: Histology. Blood from the
superior vena cava
Superior vena cava
The venous trunk which returns blood from the head, neck, upper extremities and chest.
Mediastinum and Great Vessels: Anatomy (SVC) flows directly into the right ventricle (RV) and then to the
pulmonary trunk
Pulmonary Trunk
Truncus Arteriosus, which is connected to the descending
aorta
Aorta
The main trunk of the systemic arteries.
Mediastinum and Great Vessels: Anatomy through the
ductus arteriosus
Ductus arteriosus
A fetal blood vessel connecting the pulmonary artery with the descending aorta.
Patent Ductus Arteriosus (PDA).
Structure | Remnants |
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Umbilical arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology |
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Umbilical vein |
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Ductus venosus Ductus venosus Development of the Heart |
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Ductus arteriosus Ductus arteriosus A fetal blood vessel connecting the pulmonary artery with the descending aorta. Patent Ductus Arteriosus (PDA) |
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Foramen ovale Foramen ovale An opening in the wall between the right and the left upper chambers (heart atria) of a fetal heart. Oval foramen normally closes soon after birth; when it fails to close the condition is called patent oval foramen. Patent Foramen Ovale |
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After birth, the ductus arteriosus Ductus arteriosus A fetal blood vessel connecting the pulmonary artery with the descending aorta. Patent Ductus Arteriosus (PDA) becomes the ligamentum arteriosum, as blood is able to enter the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy to be oxygenated. The foramen ovale Foramen ovale An opening in the wall between the right and the left upper chambers (heart atria) of a fetal heart. Oval foramen normally closes soon after birth; when it fails to close the condition is called patent oval foramen. Patent Foramen Ovale closes and becomes the fossa ovalis due to increased pressure in the left atrium (LA).
Image by Lecturio.After birth, the umbilical arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology become the medial umbilical ligaments, while the umbilical vein becomes the ligamentum teres Ligamentum teres A cord-like remnant structure formed from the closed left fetal umbilical vein. It is located along the lower edge of the falciform ligament. Liver: Anatomy hepatis. The ductus venosus Ductus venosus Development of the Heart becomes the ligamentum venosum Ligamentum Venosum Liver: Anatomy.
Image by Lecturio.Fetal metabolic rates are relatively low and must significantly increase to meet the metabolic needs of a growing neonate Neonate An infant during the first 28 days after birth. Physical Examination of the Newborn after birth.
Organ system | Before birth | After birth |
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Respiratory system |
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Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy |
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Blood and immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs |
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GI tract |
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Urinary system |
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Thermoregulation Thermoregulation Body temperature can be divided into external temperature, which involves the skin, and core temperature, which involves the CNS and viscera. While external temperature can be variable, the core temperature is maintained within a narrow range of 36.5-37.5ÂşC (97.7-99.5ÂşF). Body Temperature Regulation system |
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