Human Reproduction, Fetal Development, and Fetal Health

Vocabulary flashcards covering human embryonic development, placental structure and function, germ layers, stages of labor, fetal circulatory shunts at birth, prenatal diagnostic and screening tests, and maternal lifestyle factors.

Amnion

The first embryonic membrane to form (by the 8th day) that surrounds the embryo and secretes amniotic fluid to act as a shock absorber, maintain temperature, and allow free movement.

Chorion

An embryonic membrane surrounding the fetus that develops into the fetal portion of the placenta.

Yolk Sac and Allantois

Embryonic membranes that contribute to forming the outer structure of the umbilical cord.

Ectoderm

The outer embryonic germ layer that differentiates into the nervous system, skin, hair, mammary glands, and the epithelium of the mouth.

Mesoderm

The middle embryonic germ layer that differentiates into the skeleton, cardiac and skeletal muscles, connective tissue, heart, blood, stomach, and urinary system.

Endoderm

The inner embryonic germ layer that differentiates into the digestive system, lungs, thyroid, epithelium of endocrine glands, and epithelium of the respiratory tract.

Placenta

A disk-like organ formed from both fetal (chorion) and maternal tissues during the first three months of gestation that facilitates exchange of nutrients, gases, and wastes, and functions as a temporary endocrine organ.

Chorionic Villi

Finger-like projections extending from the chorion into the endometrium containing fetal capillaries bathed in maternal blood pools to allow efficient material exchange via diffusion.

Umbilical Artery

Blood vessels (two in the umbilical cord) that carry deoxygenated fetal blood containing nitrogenous wastes and carbon dioxide away from the fetus to the placenta.

Umbilical Vein

A single blood vessel in the umbilical cord that carries oxygenated, nutrient-rich blood from the placenta to the fetus.

Human Chorionic Gonadotropin (hCG)

A hormone produced in early pregnancy that maintains the corpus luteum during the first trimester to sustain progesterone and estrogen secretion.

Progesterone (in pregnancy)

A hormone produced by the corpus luteum and placenta that thickens and maintains the endometrium, maintaining fetal development and preventing premature labor.

Oestrogen (in pregnancy)

A hormone secreted during pregnancy that stimulates the growth of uterine muscles (myometrium) and the development of mammary glands.

Stage 1 of Labour (Dilation)

The initial stage of labor during which oxytocin-stimulated uterine contractions shorten and dilate the cervix to $10\text{ cm}$, forming the birth canal.

Oxytocin

A hormone released by the posterior pituitary gland that stimulates smooth muscle contractions of the uterus during labor.

Stage 2 of Labour (Expulsion)

The stage of labor spanning from complete cervical dilation until the baby is fully expelled from the vagina.

Crowning

The phase during the expulsion stage of labor when the top of the fetus's head becomes visible at the vaginal opening.

Stage 3 of Labour (Delivery of Placenta)

The final stage of labor ($5$ to $45\text{ minutes}$ post-delivery) in which uterine contractions expel the afterbirth and constrict placental blood vessels to prevent bleeding.

Afterbirth

The collective structure consisting of the delivered placenta, embryonic membranes (amnion and chorion), and umbilical cord remnants expelled in stage 3 of labor.

Foramen Ovale

An opening between the right and left atria in the fetal heart that allows oxygenated blood to bypass the fluid-filled fetal lungs.

Ductus Arteriosus

A fetal blood vessel connecting the pulmonary artery directly to the aorta, serving as a lung bypass for blood entering the right ventricle.

Ductus Venosus

A fetal blood vessel connecting the umbilical vein to the inferior vena cava, allowing oxygenated blood to bypass the undeveloped fetal liver.

Screening Test

A non-invasive or low-risk procedure (such as an ultrasound or maternal blood test) used to identify potential risks or probabilities of a health issue or genetic condition.

Diagnostic Test

A procedure (such as amniocentesis or CVS) that provides a definitive confirmation of the presence or absence of a specific genetic or physical condition.

Ultrasound

A safe screening technique using inaudible, high-frequency sound waves reflected off fetal tissues to produce visual images of the fetus in utero.

Chorionic Villus Sampling (CVS)

A diagnostic procedure performed between weeks $9$ and $19$ of pregnancy that collects fetal cells from the chorion to test for genetic disorders, carrying a $2\%$ risk of miscarriage.

Amniocentesis

A diagnostic procedure performed between weeks $16$ and $20$ of gestation where an ultrasound-guided needle extracts $10\text{--}20\text{ mL}$ of amniotic fluid to analyze floating fetal cells, carrying a risk under $0.5\%$.

Fetoscopy

A procedure using a stethoscope or a fiber-optic scope inserted into the uterus to directly observe physical abnormalities or listen to the fetal heartbeat.

Biochemical Analysis

Testing blood or body fluid samples for chemical markers indicating specific conditions, such as testing phenylalanine levels via heel prick for PKU or alpha-fetoprotein for spina bifida.

Teratogen

An agent—such as drugs, chemicals, infections, or radiation—that crosses the placenta and causes structural or developmental defects in the embryo or fetus.

Folic Acid

An essential dietary vitamin supplement recommended before and during pregnancy to support brain and spinal cord development and prevent neural tube defects.

Listeriosis

A bacterial infection caused by Listeria monocytogenes found in soft cheeses, cold meats, and unpasteurized foods that presents a high risk of miscarriage, stillbirth, or newborn infection.

Foetal Alcohol Spectrum Disorder (FASD)

A spectrum of permanent physical, cognitive, and behavioral disabilities caused by maternal alcohol consumption during pregnancy.