conception and fetal development

Question 1

A newly married couple plans to use natural family planning. It is important for them to know how long an ovum can live after ovulation. The nurse knows that teaching is effective when the couple responds that an ovum is considered fertile for:

a. 6 to 8 hours
b. 24 hours
c. 2 to 3 days
d. 1 week

Answer 1

ANS: B

Ova are considered fertile for about 24 hours after ovulation.

Ova are considered fertile for much longer than 6 to 8 hours. Most remain fertile for 24 hours.

Ova do not remain fertile for 2 to 3 days. If unfertilized by a sperm, the ovum degenerates and is reabsorbed.

Ova do not remain viable for 1 week. After 24 hours the ovum degenerates and is reabsorbed.

Question 2

2. The volume of amniotic fluid is an important factor in assessing fetal well-being. Oligohydramnios (an amniotic fluid volume of less than 300 ml) is associated with what kind of fetal anomalies?
   a. Renal
   b. Cardiac
   c. Gastrointestinal
   d. Neurologic

Answer 2

ANS: A
An amniotic fluid volume of less than 300 ml (oligohydramnios) is associated with fetal renal anomalies.

The amniotic fluid volume has no bearing on the fetal cardiovascular system.

Gastrointestinal anomalies are associated with hydramnios, or an amniotic fluid volume greater than 2 L.

The amniotic fluid volume has no bearing on the fetal neurologic system.

Question 3

3. A pregnant woman at 25 weeks of gestation tells the nurse that she dropped a pan last week and her baby jumped at the noise. Which response by the nurse is most accurate?
   a. That must have been a coincidence; babies cant respond like that.
   b. The fetus is demonstrating the aural reflex.
   c. Babies respond to sound starting at about 24 weeks of gestation.
   d. Let me know if it happens again; we need to report that to your midwife.

Answer 3

ANS: C

Babies respond to sound starting at about 24 weeks of gestation.

Fetuses can respond to sound by 24 weeks or so. Acoustic stimulations can evoke a fetal heart rate response.

There is no such thing as an aural reflex.

Stating that a report needs to be made if the fetus moves again at a noise gives the impression that something is wrong.

Question 4

4. At approximately _____ weeks of gestation, lecithin is forming on the alveolar surfaces, the eyelids open, and the fetus measures approximately 27 cm crown to rump and weighs approximately 1110 g.
   a. 20
   b. 24
   c. 28
   d. 30

Answer 4

ANS: C

These milestones occur at 28 weeks.

These milestones are not completed by 20 weeks of gestation.

These milestones in human development are not completed at 24 weeks of gestation.

These specific milestones are reached as early as 28, not 30, weeks of gestation.

Question 5

5. It is important for the nurse to understand that the placenta:
   a. Produces nutrients for fetal nutrition
   b. Secretes both estrogen and progesterone
   c. Forms a protective, impenetrable barrier to microorganisms such as bacteria and viruses
   d. Excretes prolactin and insulin

Answer 5

ANS: B

As one of its early functions, the placenta acts as an endocrine gland, producing four hormones necessary to maintain the pregnancy and support the embryo and fetus: human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogen, and progesterone.

The placenta does not produce nutrients. It functions as a means of metabolic exchange between the maternal and fetal blood supplies.

Many bacteria and viruses can cross the placental membrane.

One of the early functions of the placenta is as an endocrine gland that produces four hormones (hCG, hPL, estrogen, and progesterone) necessary to maintain the pregnancy and support the embryo and fetus.

Question 6

6. A nurse caring for a laboring woman should know that meconium is produced by:

a. Fetal intestines
b. Fetal kidneys
c. Amniotic fluid
d. The placenta

Answer 6

ANS: A

As the fetus nears term, fetal waste products accumulate in the intestines as dark green to black, tarry meconium.

Meconium is not produced by the fetal kidneys.

Meconium should not be present in amniotic fluid. This may be an indication of fetal compromise.

The placenta does not produce meconium.

Question 7

7. A woman asks the nurse, What protects my babys umbilical cord from being squashed while the babys inside of me? The nurses best response is:
   a. Your babys umbilical cord is surrounded by connective tissue called Wharton jelly, which prevents compression of the blood vessels and ensures continued nourishment of your baby.

bYour babys umbilical floats around in blood anyway.

c.You dont need to be worrying about things like that.

dThe umbilical cord is a group of blood vessels that are very well protected by the placenta.

Answer 7

ANS: A

Explaining the structure and function of the umbilical cord is the most appropriate response.

The umbilical cord does not float around in blood.

Telling the client not to worry negates her need for teaching and discounts her feelings.

The placenta does not protect the umbilical cord. The cord is protected by the surrounding Wharton jelly.

Question 8

8. The _____ is/are responsible for oxygen and carbon dioxide transport to and from the maternal bloodstream.
   a.Decidua basalis
   b Blastocyst
   c.Germ layer
   d.Chorionic villi

Answer 8

ANS: D
Chorionic villi are finger-like projections that develop out of the trophoblast and extend into the blood-filled spaces of the endometrium. The villi obtain oxygen and nutrients from the maternal bloodstream and dispose of carbon dioxide and waste products into the maternal blood.
The decidua basalis is the portion of the decidua (endometrium) under the blastocyst where the villi attach.
The blastocyst is the embryonic development stage after the morula. Implantation occurs at this stage.
The germ layer is a layer of the blastocyst.

Question 9

9. A woman who is 8 months pregnant asks the nurse, Does my baby have any antibodies to fight infection? The most appropriate response by the nurse is:
   a. Your baby has all the immunoglobulins necessary: IgG, IgM, and IgA.
   b. Your baby wont receive any antibodies until he is born and you breastfeed him.
   c. Your baby does not have any antibodies to fight infection.
   d. Your baby has IgG and IgM immunoglobulins.

Answer 9

ANS: D

During the third trimester the only immunoglobulin that crosses the placenta, IgG, provides passive acquired immunity to specific bacterial toxins. The fetus produces IgM by the end of the first trimester.

During the third trimester the only immunoglobulin that crosses the placenta, IgG, provides passive acquired immunity to specific bacterial toxins. The fetus produces IgM by the end of the first trimester. IgA immunoglobulins are not produced by the baby.

By the third trimester the fetus has IgG and IgM. Breastfeeding supplies the baby with IgA immunoglobulins.

By the third trimester, the fetus has IgG and IgM immunoglobulins to fight infection.

Question 10

10. The measurement of lecithin in relation to sphingomyelin (L/S ratio) is used to determine fetal lung maturity. Which ratio reflects maturity of the lungs?
    a. 1.4:1
    b. 1.8:1
    c. 2:1
    d. 1:1

Answer 10

ANS: C

This ratio indicates a 2:1 ratio of lecithin to sphingomyelin, an indicator of lung maturity.

1. 4:1 ratio indicates immaturity of the fetal lungs.
2. 8:1 ratio indicates immaturity of the fetal lungs.
   1: 1 ratio indicates immaturity of the fetal lungs.

Question 11

11. Sally comes in for her first prenatal examination. This is her first child. She asks you (the nurse), How does my baby get air inside my uterus? The correct response is:

a. The babys lungs work in utero to exchange oxygen and carbon dioxide.
b. The baby absorbs oxygen from your blood system.
c. The placenta provides oxygen to the baby and excretes carbon dioxide into your bloodstream.
d. The placenta delivers oxygen-rich blood through the umbilical artery to the babys abdomen.

Answer 11

ANS: C

The placenta functions by supplying oxygen and excreting carbon dioxide into the maternal bloodstream.

The fetal lungs do not function for respiratory gas exchange in utero.

The baby does not simply absorb oxygen from a womans blood system. Blood and gas transport occur through the placenta.

The placenta delivers oxygen-rich blood through the umbilical vein, not artery.

Question 12

12. The most basic information a maternity nurse should have concerning conception is:
    a. Ova are considered fertile 48 to 72 hours after ovulation
    b. Sperm remain viable in the womans reproductive system for an average of 12 to 24 hours
    c. Conception is achieved when a sperm successfully penetrates the membrane surrounding the ovum
    d. Implantation in the endometrium occurs 6 to 10 days after conception

Answer 12

ANS: D

After implantation, the endometrium is called the decidua.

Ova are considered fertile for about 24 hours after ovulation.

Sperm remain viable in the womans reproductive system for an average of 2 to 3 days.

Penetration of the ovum by the sperm is called fertilization. Conception occurs when the zygote, the first cell of the new individual, is formed.

Question 13

13. With regard to the structure and function of the placenta, the maternity nurse should be aware that:

a. As the placenta widens, it gradually thins to allow easier passage of air and nutrients
b. As one of its early functions, the placenta acts as an endocrine gland
c. The placenta is able to keep out most potentially toxic substances, such as cigarette smoke, to which the mother is exposed
d. Optimal blood circulation is achieved through the placenta when the woman is lying on her back or standing

Answer 13

ANS: B

The placenta produces four hormones necessary to maintain the pregnancy.

The placenta widens until week 20 and continues to grow thicker.

Toxic substances such as nicotine and carbon monoxide readily cross the placenta into the fetus.

Optimal circulation occurs when the woman is lying on her side.

Question 14

14. With regard to the development of the respiratory system, maternity nurses should be aware that:

a. The respiratory system does not begin developing until after the embryonic stage
b. The infants lungs are considered mature when the L/S ratio is 1:1, at about 32 weeks
c. Maternal hypertension can reduce maternal-placental blood flow, accelerating lung maturity
d. Fetal respiratory movements are not visible on ultrasound scans until at least 16 weeks

Answer 14

ANS: C

A reduction in placental blood flow stresses the fetus, increases blood levels of corticosteroids, and thus accelerates lung maturity.

Development of the respiratory system begins during the embryonic phase and continues into childhood.

The infants lungs are mature when the L/S ratio is 2:1, at about 35 weeks.

Lung movements have been seen on ultrasound scans at 11 weeks.

Question 15

15. The various systems and organs develop at different stages. Which statement is accurate?

a. The cardiovascular system is the first organ system to function in the developing human.
b. Hematopoiesis originating in the yolk sac begins in the liver at 10 weeks.
c. The body changes from straight to C-shaped at 8 weeks.
d. The gastrointestinal system is mature at 32 weeks.

Answer 15

ANS: A

The heart is developmentally complete by the end of the embryonic stage.

Hematopoiesis begins in the liver during the sixth week.

The body becomes C-shaped at 21 weeks.

The gastrointestinal system is complete at 36 weeks.

Question 16

16. Which statement concerning neurologic and sensory development is accurate?
    a. Brain waves have been recorded on an electroencephalogram as early as the end of the first trimester (12 weeks).
    b. Fetuses respond to sound by 24 weeks and can be soothed by the sound of the mothers voice.
    c. Eyes are first receptive to light at 34 to 36 weeks.
    d. At term, the fetal brain is at least one third the size of an adult brain.

Answer 16

ANS: B

Hearing develops early and is fully developed at birth.

Brain waves have been recorded at week 8.

Eyes are receptive to light at 28 weeks.

The fetal brain is about one fourth the size of an adult brain.

Question 17

1. Congenital disorders refer to those conditions that are present at birth. These disorders may be inherited and caused by environmental factors or maternal malnutrition. Toxic exposures have the greatest effect on development between 15 and 60 days of gestation. For the nurse to be able to conduct a complete assessment of the newly pregnant client, he or she should be knowledgeable regarding known human teratogens, which include:
   a. Infections
   b. Radiation
   c. Maternal conditions
   d. Drugs
   e. Chemicals

Answer 17

ANS: A, B, C, D, E

Exposure to radiation and a number of infections may result in profound congenital deformities. These include but are not limited to varicella, rubella, syphilis, parvovirus, cytomegalovirus (CMV), and toxoplasmosis. Certain maternal conditions such as diabetes and phenylketonuria (PKU) may also affect organs and other parts of the embryo during this developmental period. Drugs such as antiseizure medication and some antibiotics as well as chemicals including lead, mercury, tobacco, and alcohol also may result in structural and functional abnormalities.

Question 18

. ____________________ twins is another term for fraternal twins. These twins may be the same or different sexes and genetically are no more alike than siblings born at different times.

Answer 18

ANS:

Dizygotic

Monozygotic twins are those that develop from one fertilized ovum which then divides. These are also known as identical twins.

Question 19

. The ability of the fetus to survive outside the uterus is called ____________________.

Answer 19

ANS:

Viability

In the past the earliest age at which fetal survival could be expected was 28 weeks after conception. With modern technology and advancements in maternal and neonatal care, viability is now possible at 20 weeks after conception (22 weeks after last menstrual period [LMP], fetal weight of 500 g or more).

Question 20

3. Very fine hairs, called ____________________, appear first at 12 weeks of gestational age on the fetuss eyebrows and upper lip. By 20 weeks they cover the entire body. By 28 weeks, the scalp hair is longer than these fine hairs, which thin and may disappear by term gestation.

A

Answer 20

NS:

Lanugo

By 20 weeks of gestation the eyelashes, eyebrows, and scalp hair also begin to grow.

Question 21

True or false?
The fetal concentration of glucose is lower than the glucose level in the maternal blood because of its rapid metabolism by the fetus. Is this statement true or false?

Answer 21

ANS: T

This fetal requirement demands larger concentrations of glucose than simple diffusion can provide. Therefore, maternal glucose moves into the fetal circulation by active transport.