Maternal Week 4 Flashcards
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
The earliest age at which fetuses survive if they are born is generally accepted as _________ or at the point a fetus weighs more than ________
24 weeks
500-600 g
(also referred to as conception and impregnation) is the union of an ovum and a spermatozoon.
Fertilization
outer third of a fallopian tube, termed the
ampullar portion.
Semen ejaculation average
2.5ml of fluid containing 20 to 200 million spermatozoa per milliliter
The placenta and the membranes, which will serve as the fetal
lungs, kidneys, and digestive tract
hormone secreted by the trophoblast cells.
human chorionic gonadotropin (hCG)
The endometrium is now termed the _______ (the Latin word for _______
Decidua
Falling off
decidua has three separate areas
Decidua basalis
Decidua capsularis
Decidua vera
the part of the endometrium that lies directly under the embryo (or the portion where the trophoblast cells establish communication with maternal blood vessels)
Decidua basalis,
the portion of the endometrium that stretches or encapsulates the surface of the trophoblast
Decidua capsularis,
the remaining portion of the uterine lining. As the embryo continues to grow, it pushes the decidua capsularis before it like a blanket.
Decidua vera,
As early as the 11th or 12th day, miniature villi that resemble probing fingers, termed______________, reach out from the single layer of cells into the uterine endometrium to begin formation of the placenta.
chorionic villi
A double layer of trophoblast cells surrounds these.
syncytiotrophoblast, or the syncytial layer.
cytotrophoblast or Langhans’ layer
is present as early as 12 days’ gestation.
This layer of cells disappears, however, between the 20th and 24th weeks.
cytotrophoblast or Langhans’ layer
• This layer of cells produces various placental hormones, such as hCG, somatomammotropin (human placental lactogen [hPL]), estrogen, and progesterone
syncytiotrophoblast, or the syncytial layer.
Latin for “pancake,” which is descriptive of its size and appearance at term
placenta
• Its growth parallels that of the fetus, growing from a few identifiable cells at the beginning of pregnancy to an organ _____________cm in diameter and __________ cm in depth, covering about half the surface area of the internal uterus at term
15-20
2-3
As early as the 12th day of pregnancy, maternal blood begins to collect in the intervillous spaces of the uterine endometrium surrounding the chorionic villi.
Circulation
the rate of uteroplacental blood flow in pregnancy increases from about
50 mL/min at 10 weeks to 500 to 600 mL/min at term.
The first placental hormone produced, can be found in maternal blood and urine as early as the first missed menstrual period (shortly after implantation has occurred) through about the 100th day of pregnancy.
Human Chorionic Gonadotropin.
this is the hormone analyzed by pregnancy tests
Human Chorionic Gonadotropin.
is to act as a fail-safe measure to ensure that the corpus luteum of the ovary continues to produce progesterone and estrogen.
hCG
(primarily estriol) is produced as a second product of the syncytial cells of the placenta.
Estrogen
contributes to the woman’s mammary gland development in preparation for lactation and stimulates uterine growth to accommodate the developing fetus.
Estrogen
is often referred to as the “hormone of women”; progesterone as the “hormone of mothers.”
Estrogen
This hormone also appears to reduce the contractility of the uterus during pregnancy, preventing premature labor.
maintain the endometrial lining of the uterus during pregnancy
Progesterone
a hormone with both growth-promoting and lactogenic (milk-producing) properties.
• hPL
It is produced by the placenta beginning as early as the sixth week of pregnancy, increasing to a peak level at term. It can be assayed in both maternal serum and urine.
hPL
It promotes mammary gland (breast) growth in preparation for lactation in the mother.
hPL
It also serves the important role of regulating maternal glucose, protein, and fat levels so that adequate amounts of these nutrients are always available to the fetus
hPL
The function of these has not been well documented, but it is thought that they may contribute to decreasing the immunologic impact of the growing placenta through being part of the complement cascade
Placental Proteins
The smooth chorion eventually becomes the chorionic membrane, the outermost fetal membrane. Its purpose is to form the sac that contains the amniotic fluid.
amniotic membranes
At birth they can be seen covering the fetal surface of the placenta, giving that surface its typically shiny appearance.
amniotic membranes
is constantly being newly formed and reabsorbed by the amniotic membrane, so it never becomes stagnant.
Amniotic fluid
the amount of amniotic fluid has increased so much it ranges from
800 to 1200 ml
for any reason the fetus is unable to swallow
esophageal atresia or anencephaly
excessive amniotic fluid,
hydramnios(more than 2000 mL in total
disturbance of kidney function may cause____________555, or a reduction in the amount of amniotic fluid (less than 300 mL in total, or no pocket
oligohydramnios
The most important purpose of_______________ is to shield the fetus against pressure or a blow to the mother’s abdomen.
amniotic fluid
Amniotic fluid is slightly alkaline, with a pH of about _____
7.2
The umbilical cord is formed from the fetal membranes
(amnion and chorion)
Its function is to transport oxygen and nutrients to the fetus from the placenta and to return waste products from the fetus to the placenta.
The Umbilical Cord
It is about 53 cm (21 in) in length at term and about 2 cm (3/4 in) thick.
The Umbilical Cord
The bulk of the cord is a gelatinous mucopolysaccharide called_____________, which gives the cord body and prevents pressure on the vein and arteries that pass through it.
Wharton’s jelly
PUBS
percutaneous umbilical blood sampling
In about 20% of all births, a loose loop of cord is found around the_____________________________ at birth. If this loop of cord is removed before the newborn’s shoulders are born, so that there is no traction on it, the oxygen supply to the fetus remains unimpaired
fetal neck (nuchal cord)
the amniotic cavity, which is lined with a distinctive layer of cells, the ectoderm,
large one
the yolk sac, which is lined with entoderm cells. In humans, the yolk sac appears to supply nourishment only until implantation.
smaller cavity
the fetus derives oxygen and excretes carbon dioxide not from gas exchange in the lung but from gas exchange in the placenta.
Fetal Circulation
not yet resemble a human being.
• Length: 0.75-1 cm
Weight: 400 mg
• The spinal cord is formed and fused at the midpoint.
• Lateral wings that will form the body are folded forward to fuse at the midline.
End of 4th Gestational Week
Weigh: 25 gm (1 in)
• Organogenesis is complete.
• External genitalia are forming, but sex is not yet distinguishable by simple observation.
End of 8th Gestational Week
Length: 7-8 cm
• Weight: 45 g
• Nail beds are forming on fingers and toes.
Some reflexes, such as the Babinski reflex, are present.
End of 12th Gestational Week (First Trimester)
Length: 28-36 cm
• Weight: 550 g
• Meconium is present as far as the rectum
Eyebrows and eyelashes become well defined.
Pupils are capable of reacting to light.
VI. End of 24th Gestational Week (Second Trimester)
Length: 35-38 cm
Weight: 1200 g
• Lung alveoli begin to mature, and surfactant can be demonstrated in amniotic fluid.
• Testes begin to descend into the scrotal sac from the lower abdominal cavity.
VII. End of 28th Gestational Week
• Length: 38-43 cm
• Weight: 1600 g
• Subcutaneous tat begins to be deposited (the former stringy, “little old man”* appearance is lost)
Fetus responds by movement to sounds outside the mother’s body.
• Active Moro reflex is present.
VIII. End of 32nd Gestational Week
Length: 42-48 cm
Weight: 1800-2700 g (5-6 lb)
Amount of lanugo begins to diminish.
Most babies turn into a vertex (head down) presentation during this month.
End of 36th Gestational Week
• Length: 48-52 cm (crown to rump, 35-37 cm)
• Weight: 3000 g (7-7.5 lb)
• Fetus kicks actively, hard enough to cause the mother considerable discomfort.
• Fetal hemoglobin begins its conversion to adult hemoglobin.
- End of 40th Gestational Week (Third Trimester)
attack and disable nervous tissue.
Lead and mercury,
a drug once used to relieve nausea in pregnancy, causes limb defects.
Thalidomide,
a common antibiotic, causes tooth enamel deficiencies and, possibly, long-bone deformities.
Tetracycline,
can affect many organs: the eyes, ears, heart, and brain are the four most commonly attacked.• Two exceptions to the rule that deformities usually occur in early embryonic life are the effects caused by the organisms of syphilis and toxoplasmosis.
rubella virus
a protozoan infection, is spread most commonly through contact with uncooked meat, although it may, also be contracted through handling cat stool in soil or cat litter
Toxoplasmosis
usually causes only a mild rash and mild systemic illness in a woman, but the teratogenic effects on a fetus can be devastating
• The rubella virus
a member of the herpes virus family, is another teratogen that can cause extensive damage to a fetus while causing few symptoms in a woman
Cytomegalovirus (CMV)
It is transmitted from person to person by droplet infection such as occurs with sneezing.
Cytomegalovirus (CMV),
• The child’s skin may be covered with large petechiae (“blueberry-muffin” lesions).
there is no treatment or vaccine for the disease,
Cytomegalovirus
If the infection takes place in the first trimester, severe congenital anomalies or spontaneous miscarriage may occur.
Herpes Simplex Virus (Genital Herpes Infection)
a common viral disease in school-age children, if contracted during pregnancy, can cross the placenta and attack the red blood cells of a fetus.
• Parvovirus B19, the causative agent of erythema infectiosum (also called fifth disease),
a sexually transmitted infection, is of great concern for the maternal-fetal population despite the availability of accurate screening tests and proven medical treatment, as it is growing in incidence and places a fetus at risk
Syphilis
When the baby’s primary teeth come in, they are oddly shaped
(Hutchinson teeth)..
a multisystem disease caused by the spirochete Borrella burgdorferi, is spread by the bite of a deer tick. The highest incidence occurs in the summer and early fall.
Lyme Disease.
The largest outbreaks of the disease are found on the east coast of the United States (Mullen, 2007). After a tick bite, a typical skin rash, erythema chronicum migrans
Lyme disease
are contraindicated during pregnancy because they may transmit the viral infection to a fetus
Potentially Teratogenic Vaccines
intrauterine growth restriction (IUGR).
meperidine (Demerol) and heroin
causes severe vasoconstriction in the mother, compromising placental blood flow and perhaps dislodging the placenta.
Cocaine
their babies show a high incidence of congenital deformities and cognitive impairment.
• It was assumed in the past that these defects were the result of the mother’s poor nutritional status
Teratogenicity of Alcohol
associated with infertility in women.
been shown to cause fetal growth restriction
Teratogenicity of Cigarettes
Low birth weight in infants of __________ mothers results from vasoconstriction of the uterine vessels, an effect of nicotine. This limits the blood supply to a fetus.
Teratogenicity of Cigarettes
Rapidly growing cells are extremely vulnerable to destruction
Radiation
