Pregnancy: Zygote to Fetus and Maternal Hormonal Changes

Vocabulary flashcards covering key terms and concepts from the pregnancy development timeline, maternal anatomical changes, and hormonal regulation of labor.

zygotе

A single cell formed when a sperm fertilizes an egg; the initial cell that begins embryonic development.

cleavage

Rapid cell division after fertilization in which cells split but do not grow, producing more, smaller cells.

blastomere

Each cell resulting from cleavage; the 1-cell zygote becomes multiple blastomeres.

morula

A mulberry-shaped cluster of cells formed about three days after fertilization, marking the end of the cleavage stage.

blastocyst

A hollow sphere that forms after the morula; consists of an outer trophoblast layer and an inner cell mass.

trophoblast

Outer cell layer of the blastocyst that forms the placenta and fetal membranes.

inner cell mass

Cluster of cells inside the blastocyst that develops into the embryo.

implantation

The process by which the blastocyst attaches to and embeds in the uterine lining, around a week after ovulation.

endometrium

The lining of the uterus that receives and supports the implanted blastocyst.

corpus luteum

Ruptured follicle in the ovary that secretes estrogen and progesterone to support early pregnancy.

hCG (human chorionic gonadotropin)

A hormone produced by the trophoblast that maintains the corpus luteum and keeps pregnancy hormones high.

placenta

Temporary organ formed by maternal and embryonic tissues that transfers nutrients, hormones, and wastes between mother and fetus.

amniotic sac

Fluid-filled sac that surrounds and protects the developing embryo/fetus.

embryo

Stage of development from implantation through about week 8 when organs begin to form.

fetus

Stage after week 8 when the major organ systems are developing and maturing toward birth.

estrogen

A steroid hormone that supports pregnancy, promotes endometrial changes, and helps prepare the uterus for labor.

progesterone

A hormone that maintains uterine relaxation during pregnancy and supports the uterine environment.

relaxin

Placental hormone that loosens joints and ligaments to increase pelvic flexibility.

human placental lactogen (hPL)

Placental hormone that supports fetal growth, breast development for lactation, and maternal glucose availability.

oxytocin

Hormone that stimulates uterine contractions and is involved in labor when labor begins.

prostaglandins

Hormone-like lipids that, with oxytocin, help stimulate uterine contractions during labor.

dilation (of the cervix)

First stage of labor; the cervix opens from closed to about 10 centimeters in preparation for birth.

labor

Process of childbirth driven by uterine contractions, leading to delivery of the baby.

expulsion (delivery)

Stage of labor when the baby is pushed out through the birth canal after full dilation.

afterbirth

Expulsion of the placenta and fetal membranes following delivery.

umbilical cord

Structure linking fetus to the placenta, supplying nutrients and removing wastes.

gap junctions (in uterus)

Cell-to-cell connections in the uterus that coordinate smooth muscle contractions.

myometrium

The smooth muscle layer of the uterus that contracts during labor.

blood volume increase

Maternal blood volume can rise by up to about 40% during pregnancy, affecting heart workload and circulation.

varicose veins and hemorrhoids

Circulatory changes during pregnancy that can cause swollen veins and hemorrhoids due to higher blood volume and pressure.