care of the fetus week 4

chorionic villi

As early as the 11th or 12th day, miniature villi that resemble probing fingers, termed ________,

placenta.

each out from the single layer of cells into the uterine endometrium to begin formation of the ________

cytotrophoblast or Langhans’ layer

The middle layer, the ____________________, is present as early as 12 days’ gestation

spirochete of syphilis.

It appears to function early in pregnancy to protect the growing embryo and fetus from certain infectious organisms such as the _______________.

PLACENTA

(Latin for “pancake,” which is descriptive of its size and appearance at term) arises out of the continuing growth of trophoblast tissue.

THE MORULA PHASE

THE 8TH STEP IN IMPLANTATION

Circulation

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.

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.

Estrogen

(primarily estriol is produced as a second product of the syncytial cells of the placenta.

Human Placental Lactogen

(Human Chorionic Somatomammotropin).

hPL is a hormone with both growth-promoting and lactogenic (milk-producing)
properties. It is produced by the placenta beginning as early as the sixth week of pregnancy, increasing to a peak level at term.

C. The Amniotic Membranes

prostaglandins

not only offers support to amniotic fluid but also actually produces the fluid. In addition, it produces a phospholipid that initiates the formation of _____________, which can cause uterine contractions and maybe the trigger that initiates labor.

The Amniotic Fluid

ranges from 800 to 1200 mL
Early in fetal life,

shield the fetus against pressure or a blow to the mother’s abdomen.
it also protects the fetus from changes in temperature.

it aids in muscular development, because it allows the fetus freedom to move.

it protects the umbilical cord from pressure, protecting the fetal oxygen supply

oligohydramnios

A disturbance of kidney function may cause ____________, or a reduction in the amount of amniotic fluid

The Umbilical Cord

is formed from the fetal membranes (amnion and chorion) and provides a circulatory pathway that connects the embryo to the chorionic villi of the placenta.

Wharton’s jelly,

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.

one vein
two arteries

The outer surface is covered with amniotic membrane.
An umbilical cord contains only _________ (carrying blood from the placental villi to the fetus) but _________ (carrying blood from the fetus back to the placental villi).

END OF THE 4TH GESTATIONAL WEEK

, the human embryo is a group of rapidly growing cells but does not yet resemble a human being.

● Length: 0.75–1 cm, Weight: 400 mg

End of 8th Gestational Week

● Length: 2.5 cm (1 in), Weight: 20 g
● Organogenesis is complete.
● The heart, with a septum and valves, is beating rhythmically.

End of 12th Gestational Week (First Trimester)

Length: 7–8 cm

● Weight: 45 g

● Nail beds are forming on fingers and toes.

● Spontaneous movements are possible, although they are usually too faint to be felt by the mother.

End of 16th Gestational Week

●Length: 10–17 cm

● Weight: 55–120 g

● Fetal heart sounds are audible by an ordinary stethoscope.

● Fetus actively swallows amniotic fluid, demonstrating an intact but uncoordinated swallowing reflex; urine is present in amniotic fluid.

● Sex can be determined by ultrasound.

End of 20th Gestational Week

Length: 25 cm

● Weight: 223 g

● Spontaneous fetal movements can be sensed by the mother.

● Antibody production is possible.

● The hair forms on the head, extending to include eyebrows.

● Meconium is present in the upper intestine.

End of 24th Gestational Week (Second Trimester)

● When fetuses reach 24 weeks, or 601 g, they have achieved a practical low-end age of

viability (earliest age at which fetuses could survive if born at that time), if they are cared for after birth in a modern intensive care facility.

End of 28th Gestational Week

● 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.

● The blood vessels of the retina are formed but thin and extremely susceptible to damage from high oxygen concentrations (an important consideration when caring for preterm infants who need oxygen).

End of 32nd Gestational Week

● Length: 38–43 cm

● Weight: 1600 g

● Subcutaneous fat 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.

● Iron stores, which provide iron for the time during which the neonate will ingest only milk after birth, are beginning to be developed.

● Fingernails grow to reach the end of fingertips

End of 36th Gestational Week

● Length: 42–48 cm

● Weight: 1800–2700 g (5–6 lb)

● Body stores of glycogen, iron, carbohydrate, and calcium are deposited.

● Additional amounts of subcutaneous fat are deposited.

● Sole of the foot has only one or two crisscross creases, compared with the full crisscross

pattern that will be evident at term.

● Amount of lanugo begins to diminish.

● Most babies turn into a vertex (head down) presentation during this month.

End of 40th Gestational Week (Third Trimester)

● 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. The conversion is so rapid that,

at birth, about 20% of hemoglobin will be adult in character.

● Vernix caseosa is fully formed.

● Fingernails extend over the fingertips.

● Creases on the soles of the feet cover at least two thirds of the surface

Preventing Fetal Exposure to Teratogens

is any factor, chemical or physical, that adversely affects the fertilized ovum, embryo, or fetus.

Toxoplasmosis

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.

Pyrimethamine,

an antiprotozoal agent, may also be used. This drug is an antifolic acid drug, so it is administered with caution early in pregnancy to prevent reducing folic acid levels.

RUBELLA

virus usually causes only a mild rash and mild systemic illness in a woman, but the teratogenic effects on a fetus can be devastating.

CYTOMEGALOVIRUS

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 .

large petechiae (“blueberry-muffin” lesions).

IF THE MOTHER ACQUIRES THE CMV, THE CHILDS SKIN MAY BE COVERED WITH LARGE_____________?

Herpes Simplex Virus (Genital Herpes Infection)

cesarean birth is often advised to reduce the risk of this route of infection.

Intravenous or oral acyclovir (Zovirax)

can be administered to women during pregnancy. The primary mechanism for protecting a fetus, however, focuses on disease prevention.

Other Viral Diseases

It is difficult to demonstrate other viral teratogens, but rubeola (measles), coxsackievirus, infectious parotitis (mumps), varicella (chickenpox), poliomyelitis, influenza, and viral he- patitis all may be teratogenic

Syphilis.

a sexually transmitted infection, is of great concern for the maternal–fetal population,as it is growing in incidence and places a fetus at risk for intrauterine or congenital syphilis.

Lyme disease

a multisystem disease caused by the spirochete Borrelia burgdorferi, is spread by the bite of a deer tick. After a tick bite, a typical skin rash, erythema chronicum migrans (large, macular lesions with a clear center), develops. Pain in large joints such as the knee may develop.

Potentially Teratogenic Vaccines

Live virus vaccines, such as measles, HPV, mumps, rubella, and poliomyelitis (Sabin type), are contraindicated during pregnancy because they may transmit the viral infection to a fetus.

Teratogenic Drugs

Although not all drugs cross the placenta (heparin, for example, does not because of its large molecular size), most do. Also, even though most herbs are safe, ginseng, for example, used to improve general well-being, or senna, used to relieve constipation, may not be safe

Teratogenicity of Alcohol

• Evidence over the years has shown that when women consume a large quantity of alcohol during pregnancy, 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 (drinking alcohol rather than eating food), not necessarily the direct

Teratogenicity of Cigarettes

Cigarette smoking is associated with infertility in women. Cigarette smoking by a pregnant woman has been shown to cause fetal growth restriction

. Radiation

• Rapidly growing cells are extremely vulnerable to destruction by radiation. That makes radiation a potent teratogen to unborn children because of their high proportion of rapidly