wk 4 -- Maternal

The decidua

— After fertilization, the corpus luteum in the ovary continues to function

— Uterine endometrium to grow thickness and vascularity

— Endometrium is now termed this

— Falling off in latin

Decidua basalis

— The part of the endometrium that lies directly under the embryo

Decidua capsularis 

— The portion of the endometrium that stretches or encapsulates the surface of the trophoblast 

Decidua vera

— The remaining portion of the uterine lining

— Eventually, the embryo enlarges so much that this action brings the decidua capsularis into contact with the opposite uterine wall

Chorionic villi

— resemble probing fingers

— tiny projections of the placental tissue that contain the same genetic material

— Double layer of trophoblast cells surrounds these

11th-12th day

— reach out from the single layer of cells into the uterine endometrium to begin formation of the placenta.

— All chorionic villi have a central core of connective tissue and fetal capillaries.

The placenta

— Arising from the continuing growth of trophoblast tissue

— Covering half surface of uterus

— its growth parallels that of the fetus 

— Latin for pancake 

12th day of pregnancy

— Maternal blood begins to collect in the intervillous spaces of he uterine endometrium surrounding the chorionic villi

Third week

— oxygen and other nutrients, such as glucose, amino acids, fatty acids, minerals, vitamins, and water, osmose from the maternal blood through the cell layers of the chorionic villi into the villi capillaries

50mL/min

(Rate of uteroplacental bloodflow

— 10 weeks

500mL - 600 mL / min

(Rate of uteroplacental blood flow)

— At term

100 maternal uterine arteries 

— Supply the mature placenta

Uterine perfusion

— Placental circulation

— most efficient on side lying position

— Lifts the uterus away from the inferior vena cava, preventing blood from being trapped in woman’s lower extremities

Supine hypotension 

— If the woman lies on her back and the weight of the uterus compresses the vena cava, placental circulation can be so sharply reduced that very low maternal blood pressure and poor uterine circulation occurs

At term - Placenta

— Weighs 400-600 g (1Lbs)

Human chorionic gonadotropin

— First placental hormone produced

— Can be found in maternal blood and urine as early as the first missed menstrual period

— Testing for hCG after birth can be used as proof that placental tissue is no longer present.

Estrogen

— Hormone of women

— Contributes to the woman’s mammary gland development in preparation for lactation and stimulates uterine growth to accommodate the developing fetus

Progesterone

— Hormone of mothers

— Maintain the endometrial lining of the uterus during the pregnancy

— This hormone also appears to reduce the contractility of the uterus during pregnancy, preventing premature labor 

Human Placental lactogen

— Human Chorionic Somatomammotropin

— Hormone with both growth-promoting and lactogenic(milk-producing) properties

— Promotes mammary gland (breast) growth in preparation for lactation in the mother

— 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.

The amniotic membranes 

— Purpose is to form the sac that contains the amniotic fluid

— No nerve supply

— At birth can be seen covering the fetal surface of the placenta, giving that surface its typically shiny appearance

— it produces a phospholipid that initiates the formation of prostaglandins, which can cause uterine contractions and maybe the trigger that initiates labor

Amniotic fluid/ Gestational sac

— Constantly being newly formed and reabsorbed by he amniotic membrane, so it never becomes stagnant

— Fetus continually swallows the fluid

— Esophageal atresia or anencephaly are two common reasons why the fetus cannot swallow the fluid

Hydramnios

— Tends to occur in women with diabetes

— Hyperglycemia causes excessive fluid shifts into the amniotic space

Oligohydramnios

— Disturbance of kidney function

— Affects fetus movement due to low amniotic fluid

Umbilical cord

— Transport oxygen and nutrients to the fetus from the placenta and to return waste products from the fetus to the placenta 

— It is about 53 cm (21 in) in length at term and about 2 cm (3 ⁄4 in) thick.

Wharton’s jelly

— Bulk of the cord is a gelatinous mucopolysaccharide called

— Gives pressure the vein and arteries that pass through it

One vein

— Carrying blood from the placental villi to the fetus

Two arteries

— Carrying blood from the fetus back to the fetus back to the placental villi

8 weeks’ gestation

— End of the embryonic period

— All organ systems are complete

— The embryo will begin to develop at the point where the three cell layers (ectoderm, entoderm, and mesoderm) meet, called the embryonic shield

Organogenesis

— Organ formation

Ectoderm

— Central nervous system (brain and spinal cord)

— Peripheral nervous system

— Skin, hair, nails, and tooth enamel
— Sense organ

Mesoderm

— Upper portion of the urinary system (kidneys and ureters)

Endoderm

— Lower urinary system

Fetal circulation

— As early as the third eek of the intrauterine life, fetal blood begins to exchange nutrients with the maternal circulation across the chorionic villi

— Fetus derives oxygen and excretes carbon dioxide from gas exchange in the placenta

Fetal blood circulation

— Blood arriving to the fetus is highly oxygenated

— blood enters the fetus through the umbilical vein (carries oxygenated blood, toward the fetal heart)

End of 4th gestational eek

— Embryo - rapidly growing cells

— Does not yet resemble a human being

— The head folds forward and becomes prominent, representing about one-third of the entire structure

— The back is bent so that the head almost touches the tip of the tail.

— Arms and legs are budlike structures 

— Basic eyes, ears, and nose are visible 

End of 8th Gestational week

— Organogenesis is complete

— The heart, with a septum and valves, is beating rhythmically

— Facial features are now visible

—  Arms and legs have developed 

— External genitalia are forming, but sex is not yet distinguishable

— Can now under go ultrasound

end of 12th gestational week

— First trimester

— Nail beds are forming on fingers and toes 

— Movements present butt usually to faint to be felt

— Urine secretions begin

— Bone ossification centers begin to form 

— Tooth buds are present 

— Heartbeat audible through doppler technology

End of 16th gestational week

— Heart sounds audible by stethoscope

— Lanugo is well formed

— Sex determined by ultrasound

— Fetus actively swallows amniotic fluid

End of 20th gestational week

— Movement sensed by mother

— Meconium is present in the upper intestine

— Brown fat - a special fat that will aid in temperature regulation at birth, begins to be formed behind the kidneys, sternum, and posterior neck.

— Vernix caseosa begin to form and cover the skin

— Passive antibody transfer from mother to fetus begins.

Brown fat

— A special fat that will aid in temperature regulation at birth, begins to be formed behind the kidneys, sternum, and posterior neck

Meconium

— feces of fetus

end of 24th gestational week

— Meconium is present as far as the rectum 

— Eyebrows and eyelash are ell defined

— Can see and hear

— Earliest age at which fetuses could survival if born as a premature

End of 28th gestational walk

— 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

End of 32nd gestational week

— 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

— Fingernails grow to reach the end of fingertips.

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

End of 36th gestational week

— Sole of the foot has only one or two crisscross crease

— Amount of lanugo begins to diminish.

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

End of 40th gestational week

— Fetus kicks actively, hard enough to cause the mother considerable discomfort

— Vernix caseosa fully formed

Lead ad mercury

— Attack and disable nervous tissue

Thalidomide

— A drug once used to relieve nausea in pregnancy, causes limb defects

Tetracycline 

— A common antibiotic, causes tooth enamel deficiencies and, possibly, long-bone deformities 

The rubella virus

— Can affect many organs: the eyes, ears, heart, and brain