MCN MIDTERMS Flashcards
- Immediately before and after birth
- Begins at 22 completed weeks of gestation and
ends 7 completed days after birth - “Perinatal and maternal health are closely
linked” (WHO)
Perinatal Period
- Time span from fertilization to birth.
- First day of woman’s last menstrual period to
38 weeks.
Gestation Period
- Before birth
- Embryological development
➢Embryo – developing human for first
2 months after fertilization
➢All major adult organs are present
Prenatal Period
➢Fetus – from 9 weeks until birth
➢By end of 3rd month, placenta is
functioning
Fetal Development
➢First 42 days after birth
➢First 4 weeks of a child’s life –
changes are very rapid
NUCAMA340
©LPD
Neonatal Period
From ovulation to fertilization
Ovum
From fertilization to implantation
Zygote
From implantation to 5–8 weeks
Embryo
From 5–8 weeks until term
Fetus
Developing embryo and placental
structures throughout pregnancy
Conceptus
The earliest age at which fetuses
survive if they are born is generally
accepted as 24 weeks or at the point a
fetus weighs more than 500–600 g
Age of viability
(first 2 weeks,
beginning with fertilization)
Pre-embryonic
(weeks 3 through 8)
embryonic
(from week 8 through
birth
Fetal
also referred to as conception or
impregnation
Fertilization
the union of an ovum and a
spermatozoon
fertilization
Occurs in the outer third of a fallopian
tube, termed the ampullar portion.
Never a certain occurrence, depending on
the following factors:
Equal maturation of both sperm and
ovum
Ability of the sperm to reach the
ovum
Ability of the sperm to penetrate the
zona pellucida and cell membrane of
ovum and achieve fertilization
Fertilization
a ring of mucopolysaccharide
fluid surrounding the ovum upon extrusion from
the Graafian follicle.
Zona Pellucida
a circle of cells protecting the
ovum.
Corona radiata
- a proteolytic enzyme released by
the spermatozoa and dissolves the Corona radiata.
Hyaluronidase
2.5 mL
Sperm per ejaculation: 400 million (20 to 200
million per mL)
Average semen volume
latin for “falling off” because it
will be discarded after birth of the child.
decidua
secreted by the trophoblast cells; causes
the uterine endometrium to continue to
grow in thickness and vascularity.
Human Chorionic Gonadotropin
– lies directly under
the embryo and communicates with
maternal blood vessels
Decidua basalis
– stretches and
encapsulates the embryo
Decidua capsularis
– remaining
portion of the uterine lining
Decidua vera/parietalis
Miniature, resembling probing fingers
▪ Arise from the trophoblast cells and
form the placenta as early as the 11th
or 12th day after fertilization.
Surrounded by a double layer of cells
▪ produce placental hormones (hCG,
hPL, estrogen, and progesterone)
▪ protect the growing embryo from
certain infectious organisms
▪ Disappear between the 20th and
24th week of pregnancy
Chorionic Villi
Latin for “pancake” descriptive of its
appearance and size at term.
▪ Weighs about 400-600 grams at term (1/6
of the fetus’ weight)
▪ Grows from trophoblastic cells at the
beginning of pregnancy to an organ 15 to
20 cm in diameter and 2 to 3 cm in depth
▪ Covers about half the surface area of the
internal uterus at term.
Placenta
Functions of Placenta?
Nutrition
Respiration
Hormone production
Excretion
Protection
smooth, shiny; separated
from the center; blood clots are usually
contained within the membranes →
less bleeding
Schultz
‘dirty’, rough and irregular;
separated from the edges; blood clots
are not contained within the
membranes → more visible bleeding.
Duncan
classified
according to how much of the
cervix is covered by the
placenta. Here are the main
Placenta previa
the
placenta completely covers
the cervix.
Complete Placenta Previa
the
placenta partially covers the
cervix.
Partial Placenta Previa
the
placenta is located at the edge of the
cervix.
Marginal Placenta Previa
the placenta is
near the cervix but does not cover it.
Low-Lying Placenta
▪ Form beneath the chorion
▪ Dual-walled sac (chorion –
outermost; amnion – innermost)
containing the amniotic fluid.
These walls fuse together as the
pregnancy progresses.
▪ Does NOT have nerve supply
▪ Support and produce amniotic
fluid.
▪ produce a phospholipid that
initiates the formation of
prostaglandins, which may be the
trigger that initiates labor
Amniotic membranes (amion)
At term, it amounts to 800 to 1,200 mL
▪ Slightly alkaline (pH 7 - 7.5)
▪ Constantly being newly formed and
absorbed (every 3 hrs) by direct contact
with the fetal surface of the placenta.
▪ Major methods of absorption:
▪ The fetus continually swallows the
fluid
▪ Absorbed from the fetal intestine
into the fetal bloodstream → to the
umbilical arteries and to the
placenta.
Amniotic fluid
meconium-stained
greenish
Red wine
abruptio placenta