Chapter 8 Flashcards
The period from the beginning of the ninth week to birth is known as the ___
fetal period
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 13-16
Crl: 9-14cm
Weight: 60-200
The length of the fetus is usually indicated as the___ (sitting height) or as the ___, the measurement from the vertex of the skull to the heel (standing height)
crown-rump length (CRL) - crown heel length (CHL)
In general, the length of pregnancy is considered to be 280 days, or 40 weeks after the onset of the last normal menstrual period (LNMP) or, more accurately, 266 days or 38 weeks after fertilization. True/ False
True
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 9-12
Crl: 5-8cm
Weight: 10-45g
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 17-20
Crl: 15-19cm
Weight: 250-450g
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 25-28
Crl: 24-27cm
Weight: 900-1300g
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 21-24
Crl: 20-23cm
Weight: 500-820g
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 29-32
Crl: 28-30cm
Weight: 1400 - 2100g
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 33-36
Crl: 31-34cm
Weight: 2200-2900g
Growth in length and weight during the fetal period. Give the crl (cm) and weight (g) in wk 37-38
Crl: 35-36cm
Weight: 3000-3400g
During the ____, the face becomes more human looking . The eyes, initially directed laterally, move to the ventral aspect of the face, and the ears come to lie close to their definitive position at the side of the head. The limbs reach their relative length in comparison with the rest of the body, although the lower limbs are still a little shorter and less well developed than the upper extremities
third month
___ are present in the long bones and skull by the 12th week. Also, by the 12th week, external genitalia develop to such a degree that the sex of the fetus can be determined by external examination (ultrasound)
Primary ossification centers
During the ___ and ___, the fetus lengthens rapidly, and at the end of the first half of intrauterine life, its CR is approximately 15 cm, about half the total length of the newborn
fourth and fifth months
During the 6th week, ____, but by the 12th week, the loops have withdrawn into the abdominal cavity.
intestinal loops cause a large swelling (herniation) in the umbilical cord
The fetus is covered with fine hair, called __; eyebrows and head hair are also visible
lanugo hair
During the ____, movements of the fetus can be felt by the mother
fifth month
During the ___, the skin of the fetus is reddish and has a wrinkled appearance because of the lack of underlying connective tissue
sixth month
During the ___, weight increases considerably, particularly during the last 2.5 months, when 50% of the full-term weight (approximately 3,200g) is added
second half of intrauterine life
Development of taste buds appear at what wk?
7
Development of some sounds can be heard at what wk?
24-26
Development of swallowing at what wk?
10
Development of eyes sensitive to light at what wk?
28
A valuable tool for assisting in this determination is __, which can provide an accurate (1 to 2 days) measurement of CRL during the 7th to 14th weeks.
ultrasound
Development of respiratory movements appear at what wk?
14-16
At the end of the ___, the skull has the largest circumference of all parts of the body, an important fact with regard to its passage through the birth canal. At the time of birth, the weight of a normal fetus is 3,000 to 3,400 g, its CRL is about 36 cm, and its CHL is about 50 cm. Sexual characteristics are pronounced, and the testes should be in the scrotum.
ninth month
Development of sucking movements at what wk?
24
During the last 2 months, the fetus obtains well-rounded contours as the result of deposition of subcutaneous fat. By the end of intrauterine life, the skin is covered by a whitish, fatty substance (____) composed of secretory products from sebaceous glands
vernix caseosa
Most fetuses are born within 10 to 14 days of the calculated delivery date. If they are
born much earlier, they are categorized as ___; if born later, they are considered ___
premature - postmature
Measurements commonly used in the 16th to 30th weeks are ____, ____ and ___, and ____
biparietal diameter (BPD), head and abdominal circumference, and femur length
In contrast, the terms ___ and ___ take into account gestational age
intrauterine growth restriction [IUGR] - small for gestational age [SGA]
The average size of a newborn is 2,500 to
4,000 g [6 to 9 lb] with a length of 51 cm [20 in]. The term ___ refers to a weight <2,500 g, regardless of gestational age
low birth weight [LBW]
Many infants weigh <2,500 g because they are ____ [born before 37 weeks of
gestation]
Preterm
___ is a term applied to infants who do not attain their optimal intrauterine growth. These infants are pathologically small and at risk for poor outcomes
IUGR
Infants who are ___ have a birth weight that is below the 10th percentile for their gestational age. These babies may be pathologically small [they may have IUGR]
or they may be constitutionally small [healthy but smaller in size]
SGA
For example, babies with IUGR have been shown to have a greater chance as adults to develop a metabolic disorder later in life, such as obesity, hypertension, hypercholesterolemia, cardiovascular disease, and type 2 diabetes [called
the ____].
Barker hypothesis
The major growth-promoting factor during
development before and after birth is ___, which has ___ and ____.
insulin-like growth factor 1 [lGF-1]
mitogenic and anabolic effects
Mutations in the IGF-1 gene result in IUGR, and this growth retardation is continued after birth. In contrast to the prenatal
period, postnatal growth depends on ___
growth hormone [GH]
Mutations in the GHR result in ___, which is characterized by marked short stature, and sometimes blue sclera
Laron dwarfism
Maternal blood is delivered to the placenta by spiral arteries in the uterus. Erosion ofthese maternal vessels to release blood into intervillous spaces is accomplished by ___ by cytotrophoblast cells
endovascular invasion
During the following months, numerous small extensions grow out from existing stem villi and extend as free villi into the surrounding ___ or ___
lacunar or intervillous spaces
These pieces, known as ___, enter the maternal circulation and usually degenerate without causing any
symptoms
syncytial knots
___ is a condition characterized by maternal hypertension and proteinuria due to reduced organ perfusion and occurs in approximately 5% of pregnancies
Preeclampsia
In the early weeks of development, villi cover the entire surface of the chorion. As
pregnancy advances, villi on the embryonic pole continue to grow and expand, giving rise to the ___ (bushy chorion)
chorion frondosum
Villi on the abembryonic pole degenerate, and by the third month, this side of the chorion, now known as the ___, is smooth
chorion laeve
The difference between the embryonic and abembryonic poles of the chorion is also reflected in the structure of the __, the functional layer of the endometrium, which is shed during parturition
decidua
The decidua over the chorion frondosum, the ____, consists of a compact layer of large cells, decidual cells, with abundant amounts of lipids and glycogen
decidua basalis
The decidua over the chorion frondosum, the decidua basalis, consists of a compact layer of large cells, ___, with abundant amounts of lipids and glycogen
decidual cells
This layer, the ___, is tightly connected to the chorion
decidual plate
The decidual layer over the abembryonic pole is the ____
decidua capsularis
Subsequently, the chorion laeve comes into contact with the uterine wall (____) on the opposite side of the uterus, and the two fuse, obliterating the uterine lumen
decidua parietalis
Hence, the only portion of the chorion participating in the exchange process is the chorion frondosum, which, together with the decidua basalis, makes up the ___
placenta
Similarly, fusion of the amnion and chorion to form the ___ obliterates the chorionic cavity
amniochorionic membrane
On the fetal side, the placenta is bordered by the ____; on its maternal side, it is bordered by the decidua basalis, of which the ___ is most intimately incorporated into the placenta
chorionic plate - decidual plate
By the beginning of the fourth month, the placenta has two components:
(1) a ___, formed by the chorion frondosum
(2) a ___, formed by the decidua basalis
fetal portion - maternal portion
In the ___, trophoblast and decidual cells intermingle. This zone, characterized by decidual and syncytial giant cells, is rich in amorphous extracellular material. By this time, most cytotrophoblast cells have degenerated
junctional zone
When the placenta is viewed from the ___, 15 to 20 slightly bulging areas, the ___, covered by a thin layer of decidua basalis, are clearly recognizable
maternal side - cotyledons
During the fourth and fifth months, the decidua forms a number of ___, which project into intervillous spaces but do not reach the chorionic plate
decidual septa
As a result of this septum formation, the placenta is divided into a number of compartments, or ___
cotyledons
The ____ of the placenta is covered entirely by the chorionic plate. A number of large arteries and veins, the ___, converge toward the umbilical cord
fetal surface - chorionic vessels
Rarely, however, does it insert into the chorionic membranes outside the placenta (_____)
velamentous insertion
This process is an example of ____, and if the maternal response is sufficient, the antibodies will attack and hemolyze fetal red blood cells, resulting in hemolytic disease of the fetus and newborn
isoimmunization
The ___, which separates maternal and fetal blood, is initially composed of four layers:
(1) the endothelial lining of fetal vessels
(2) the connective tissue in the villus core
(3) the cytotrophoblastic layer
(4) the syncytium
placental membrane
Sometimes called the ___, the placental membrane is not a true barrier, as many substances pass through it freely
placental barrier
Because the maternal blood in the intervillous spaces is separated from the fetal blood by a chorionic derivative, the human placenta is considered to be of the ____
hemochorial type
This process is an example of isoimmunization, and if the maternal response is sufficient, the antibodies will attack and hemolyze fetal red blood cells, resulting in ____
hemolytic disease of the fetus and newborn
Previously, the disease was called ____ because in some cases, severe hemolysis stimulated an increase in production of fetal blood cells called erythroblasts
erythroblastosis fetalis
Previously, the disease was called erythroblastosis fetalis because in some cases, severe hemolysis stimulated an increase in production of fetal blood cells called ___
erythroblasts
In rare cases, the anemia becomes so severe that ___ [edema and effusions into the body cavities] occurs, leading to fetal death
fetal hydrops
Most severe cases are caused by antigens from the ____ blood group system
CDE [Rhesus]
The D or ___ is the most dangerous because immunization can result from a single exposure and occurs earlier and with greater severity with each succeeding pregnancy. The maternal antibody response occurs in cases when the fetus is D [Rh]—positive and the mother is D [Rh]—negative and is elicited when fetal red blood cells enter the maternal system because of small areas of bleeding at the
surface of placental villi or at birth
Rh antigen
Main functions of the placenta are
(1) ___ between maternal and fetal bloodstream
(2) ____
exchange of metabolic and gaseous products - production of hormones
Immunological competence begins to develop late in the first trimester, by which time the fetus makes all of the components of ___
complement
Immunoglobulins consist almost entirely of ___, which begins to be transported from mother to fetus at approximately 14 weeks
maternal immunoglobulin G (IgG)
By the end of the fourth month, the placenta produces ___ in sufficient amounts to maintain pregnancy if the corpus luteum is removed or fails to function properly
progesterone
Even more dangerous was the use of the synthetic estrogen ____, which easily crosses the placenta. This compound produced clear-cell carcinoma of the vagina and abnormalities of the cervix and uterus in females and in the testes of males in individuals who were exposed to the compound during their intrauterine life
diethylstilbestrol [DES]
In addition to progesterone, the placenta produces increasing amounts of ___, predominantly ___, until just before the end of pregnancy, when a maximum level is reached
estrogenic hormones - estriol
During the first 2 months of pregnancy, the syncytiotrophoblast also produces ___, which maintains the corpus luteum. This hormone is excreted by the mother in the urine, and in the early stages of gestation, its presence is used as an indicator of pregnancy
human chorionic gonadotropin (hCG)
Another hormone produced by the placenta is __ (formerly placental lactogen)
somatomammotropin
Another hormone produced by the placenta is somatomammotropin (formerly ___)
placental lactogen
The oval line of reflection between the amnion and embryonic ectoderm (___) is the primitive umbilical ring
amnio-ectodermal junction
The oval line of reflection between the amnion and embryonic ectoderm (amnio-ectodermal junction) is the ____
primitive umbilical ring
At the fifth week of development, the following structures pass through the ring:
(1) the ____, containing the allantois and the umbilical vessels, consisting of two arteries and one vein
(2) the ___, accompanied by the vitelline
vessels
(3) the ___ and ____
connecting stalk - yolk stalk (Vitelline duct) - canal connecting the intraembryonic and extraembryonic
The yolk sac proper occupies a space in the ___, that is, the space between the amnion and chorionic plate
chorionic cavity
The abdominal cavity is temporarily too small for the rapidly developing intestinal loops, and some of them are pushed into the extraembryonic space in the umbilical cord. These extruding intestinal loops form a ____
physiological umbilical hernia
During further development, the amniotic cavity enlarges rapidly at the expense of
the chorionic cavity, and the amnion begins to envelop the connecting and yolk sac stalks, crowding them together and giving rise to the ____
primitive umbilical cord
When the allantois and the vitelline duct and its vessels are also obliterated, all that remains in the cord are the umbilical vessels surrounded by ___
Wharton jelly
At birth, the umbilical cord is approximately 1 to 2 cm in diameter and 50 to 60 cm long. It is tortuous, causing ___
false knots
Normally, there are two arteries and one
vein in the umbilical cord. In 1 in 200 newborns, however, only a ___ is present, and these babies have approximately 20% chance of having cardiac and other vascular defects
single umbilical artery
Occasionally, tears in the amnion result in
____ that may encircle part of the fetus, particularly the limbs and digits. Amputations, ____, and other abnormalities, including craniofacial deformations, may result
amniotic bands - ring constrictions
____ is the term used to describe an excess of amniotic fluid [1,500 to 2,000 mL], whereas ____ refers to a decreased amount [<400 mL]
Hydramnios or polyhydramnios - oligohydramnios
_____ refers to rupture of the membranes before uterine contractions begin and occurs in 10% of pregnancies
Premature rupture of the membranes [PROM]
___ PROM occurs before 37 completed weeks of pregnancy, occurs in 3% of pregnancies, and is a common cause of preterm labor
Preterm
Approximately 90% of twins are ___ or ___, and their incidence increases with maternal age (doubling at age 35 years) and with fertility procedures, including ART
dizygotic, or fraternal
____ is produced by uterine contractions that force the amniotic sac against the cervical canal like a wedge, or if the membranes have ruptured, then pressure will be exerted by the presenting part of the fetus, usually the head
Stage 1
Occasionally, each dizygotic twin possesses red blood cells of two different types (___), indicating that fusion of the two placentas was so intimate that red cells were exchanged
erythrocyte mosaicism
The second type of twins, which develops from a single fertilized ovum, is ___ or ___ twins
monozygotic or identical
For the first 34 to 38 weeks of gestation, the uterine myometrium does not respond to signals for ___
parturition (birth)
During the last 2 to 4 weeks of pregnancy, however, this tissue undergoes a transitional phase in preparation for the onset of ___
labor
Labor itself is divided into three stages:
(1) ____ (thinning and shortening) and dilatation of the cervix (this stage ends when the cervix is fully dilated)
(2) ____
(3) ____
effacement - delivery of the fetus - delivery of the placenta and fetal membranes
___ is also assisted by uterine contractions, but the most important force is provided by increased intra-abdominal pressure from contraction of abdominal muscles
Stage 2
___ requires uterine contractions and is aided by increasing intra-abdominal pressure
Stage 3
Factors initiating labor are not known and may involve “______,” in which pregnancy-supporting factors [e.g., hormones] are withdrawn, or active induction caused by stimulatory factors targeting the uterus
retreat from maintenance of pregnancy
The term ___ refers to the death of one fetus. This disappearance, which occurs in the first trimester or the early second trimester, may result from resorption or formation of a fetus papyraceus
vanishing twin
Factors initiating labor are not known and may involve “retreat from maintenance of pregnancy,” in which pregnancy supporting factors [e.g., hormones] are withdrawn, or ____ caused by stimulatory factors targeting the uterus
active induction
Preterm birth [delivery before 37 completed weeks] of ____ occurs in approximately 12% of births in the United States and is a leading cause of infant mortality and also contributes significantly to morbidity
premature infants
Unfortunately, a lack of knowledge about these factors has restricted progress in preventing ___
preterm birth
The umbilical cord, surrounded by the
amnion contains
(1) ____
(2) ____
(3) ___, which serves as a protective cushion for the vessels
two umbilical arteries - one umbilical vein -Wharton jelly
The placenta consists of two components:
(1) a fetal portion, derived from the ___ or villous chorion
(2) a maternal portion, derived from the ____.
The space between the chorionic and decidual plates is filled with ___ of maternal blood
chorion frondosum - decidua basalis - intervillous lakes
At the end of pregnancy, a number of changes that occur in the placenta may indicate reduced exchange between the two circulations. These changes include
(1) an increase in fibrous tissue in the core of the villus
(2) thickening of basement membranes in fetal capillaries
(3) obliterative changes in small capillaries of the villi
(4) deposition of fibrinoid on the surface of the villi in the junctional zone and in the chorionic plate
- Which of the ff are false?
None. All are true
