Fetal Development and Pregnancy Fundamentals

Practice flashcards covering fetal development stages, terminology, and principles of pregnancy from cellular growth to the third trimester.

Ovum

An egg cell in the female reproductive system.

Zygote

The cell formed when a sperm cell and an egg cell (ovum) fuse together.

Mitosis

The process of DNA replication or duplication where one parent cell divides into two daughter cells to create copies.

Meiosis

A type of cell division that creates sex cells containing half of the normal amount of genetic information.

XX chromosome

The chromosome combination that signifies a female fetus.

XY chromosome

The chromosome combination that signifies a male fetus.

Progesterone

A hormone that helps maintain the uterine lining and reduces early uterine contractions to lower the risk of early labor.

Estrogen

A hormone produced by the placenta that is important for fetal growth and development.

hCG (Human Chorionic Gonadotropin)

A hormone detected in pregnancy tests that signals the corpus luteum that a pregnancy has occurred.

Corpus Luteum

A group of cells in the ovary formed after ovulation that produces hormones, especially progesterone, to prepare the uterus for pregnancy.

72 hours

The duration of time sperm can typically survive in a fertilized ovum after ejaculation.

24 to 48 hours

The period of time after ovulation that an ovum remains fertilizable.

Amnion

The inner membrane that directly surrounds the embryo and contains the amniotic fluid.

Chorion

The outer membrane surrounding the amniotic cavity that eventually forms the fetal portion of the placenta.

Amniotic Sac

A structure that surrounds and protects the embryo during pregnancy, formed by the chorion and the amnion working together.

Amniotic Fluid

A watery substance that cushions the fetus from injury, prevents the amnion from adhering to the fetus, facilitates movement, and maintains temperature.

800 to 1,200 mL

The typical volume of amniotic fluid present in the sac by the end of a pregnancy.

Day 12

The time after conception when amniotic fluid typically begins to form.

Villi

Tiny finger-like projections on the chorion that contain blood vessels and help the placenta attach to the uterus for nutrient exchange.

Placenta

An organ that acts as the fetus' lifeline, providing support, nourishment, and protection while allowing the exchange of oxygen, nutrients, and waste.

Fetal Circulation

A process beginning around the fourth week of gestation where the fetus depends entirely on the mother for oxygen and nutrients.

Umbilical Cord

The structure connecting the fetus to the placenta that facilitates the reception of oxygen and nutrients.

Shunts

Openings or pathways in fetal circulation that redirect blood flow because the lungs and liver are not yet fully functioning.

Teratogens

Substances or environmental factors that a pregnant person is exposed to that can interfere with fetal development or cause complications.

Phenytoin

A specific medication mentioned that is known to cause serious birth defects if taken during pregnancy.

Toxoplasmosis

An infection that can cross the placenta and harm the fetus, leading to serious congenital conditions.

Mercury

An environmental exposure found in fish like tuna that can cause damage to fetal tissues.

First Trimester

The period of pregnancy from conception through the end of week $12$, primarily characterized by organ formation.

Week 3 (Development)

The stage where the embryo measures about $2\text{ mm}$, and the amniotic sac and placenta begin to form.

Week 4 (Development)

The stage when the embryo is $4\text{ to }6\text{ mm}$, the heart begins beating and pumping blood, and limb buds form.

Week 6 (Development)

The stage where fingers and toes develop, skeletal cartilage forms, facial features outline, and the liver begins to work.

Week 8 (Development)

The point when all internal organs are formed and the embryo starts to look more human.

Week 10 (Development)

The stage when fingernails and toenails grow, eyelids fuse shut, and fingerprints become visible.

Second Trimester

The period of pregnancy from week $13$ through week $27$, known for rapid growth and fetal movement.

Month 4 (Development)

The stage when the fetal heartbeat is audible by a Doppler, the skeleton is established, and lanugo forms.

Doppler

A device used to hear the fetal heartbeat, which is typically possible by the fourth month.

Lanugo

Fine hair on the fetus that is established during the fourth month of development.

Month 5 (Development)

The stage when the fetus weighs about $435\text{ g}$, vernix caseosa forms, and the fetus can react to sound.

Vernix Caseosa

A white, cottage cheese-like protective coating that forms on the skin of the fetus.

Quickening

A term describing the fetal movement felt by the mother, often as a flutter or bubble, starting around month five.

Month 6 (Development)

The stage when fetal eyelids open, respiratory movements begin, and alveoli start to form.

Alveoli

Structures in the lungs that begin to form during the sixth month of fetal development.

Third Trimester

The final stage of pregnancy where body fat increases and lungs reach maturity.

Month 7 (Development)

The stage when body fat increases for temperature regulation, hiccups may occur, and the fetus can see light and hear music.

Month 8 (Development)

The stage where the fetus weighs about $2\text{ to }2.5\text{ grams}$ and develops creases on the soles of the feet.

Month 9 (Development)

The final developmental stage where lungs are almost mature and the fetus moves into the vertex position.

Vertex Position

The head-down positioning of the fetus in preparation for labor.

Monozygotic Twins

Identical twins resulting from a single fertilized egg that splits into two embryos, sharing $100\%$ of genetic material.

Dizygotic Twins

Fraternal twins resulting from two separate eggs fertilized by two different sperm, sharing half of their genetic makeup.

Fraternal Twins (Structures)

Twins characterized by having two separate placentas and two separate amniotic sacs.