Flashcards in Chapter 12 Deck (38):
1. A newly married couple plans to use the natural family planning method of contraception. Understanding how long an ovum can live after ovulation is important to them. The nurse knows that his or her teaching was effective when the couple responds that an ovum is considered fertile for which period of time?
a. 6 to 8 hours
b. 24 hours
c. 2 to 3 days
d. 1 week
Most ova remain fertile for approximately 24 hours after ovulation, much longer than 6 to 8 hours. However, ova do not remain fertile for 2 to 3 days or are viable for 1 week. If unfertilized by a sperm after 24 hours, the ovum degenerates and is reabsorbed.
2. What kind of fetal anomalies are most often associated with oligohydramnios?
An amniotic fluid volume of less than 300 ml (oligohydramnios) is often 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.
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 can’t respond like that.”
b. “The fetus is demonstrating the aural reflex.”
c. “Babies respond to sound starting at approximately 24 weeks of gestation.”
d. “Let me know if it happens again; we need to report that to your midwife.”
Babies respond to external sound starting at approximately 24 weeks of gestation. Acoustic stimulations can evoke a fetal heart rate response. There is no such thing as an aural reflex. The last statement is inappropriate and may cause undue psychologic alarm to the client.
4. At a routine prenatal visit, the nurse explains the development of the fetus to her client. 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. The client is how many weeks of gestation at today’s visit?
These milestones in human development occur at 28 weeks of gestation. These milestones have not occurred by 20 or 24 weeks of gestation but have been reached before 30 weeks of gestation.
5. Which statement regarding the structure and function of the placenta is correct?
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
As one of its early functions, the placenta acts as an endocrine gland, producing four hormones necessary to maintain the pregnancy and to support the embryo or 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.
6. A woman in labor passes some thick meconium as her amniotic fluid ruptures. The client asks the nurse where the baby makes the meconium. What is the correct response by the nurse?
a. Fetal intestines
b. Fetal kidneys
c. Amniotic fluid
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 nor should it be present in the amniotic fluid, which may be an indication of fetal compromise. The placenta does not produce meconium.
7. A woman asks the nurse, “What protects my baby’s umbilical cord from being squashed while the baby’s inside of me?” What is the nurse’s best response?
a. “Your baby’s umbilical cord is surrounded by connective tissue called Wharton’s jelly, which prevents compression of the blood vessels.”
b. “Your baby’s umbilical cord floats around in blood and amniotic fluid.”
c. “You don’t need to be worrying about things like that.”
d. “The umbilical cord is a group of blood vessels that are very well protected by the placenta.”
Explaining the structure and function of the umbilical cord is the most appropriate response. Connective tissue called Wharton’s jelly surrounds the umbilical cord, prevents compression of the blood vessels, and ensures continued nourishment of the embryo or fetus. The umbilical cord does not float around in blood or fluid. Telling the client not to worry negates her need for information and discounts her feelings. The placenta does not protect the umbilical cord.
8. Which structure is responsible for oxygen and carbon dioxide transport to and from the maternal bloodstream?
a. Decidua basalis
c. Germ layer
d. Chorionic villi
Chorionic villi are fingerlike 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 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.
9. A woman who is 8 months pregnant asks the nurse, “Does my baby have any antibodies to fight infection?” What is the most appropriate response by the nurse?
a. “Your baby has all the immunoglobulins necessary: immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA).”
b. “Your baby won’t 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.”
During the third trimester, IgG is the only immunoglobulin that crosses the placenta; it provides passive acquired immunity to specific bacterial toxins. However, the fetus produces IgM by the end of the first trimester. IgA immunoglobulins are not produced by the baby. Therefore, by the third trimester, the fetus has both IgG and IgM. Breastfeeding supplies the newborn infant with IgA.
10. The measurement of lecithin in relation to sphingomyelin (lecithin/sphingomyelin [L/S] ratio) is used to determine fetal lung maturity. Which ratio reflects fetal maturity of the lungs?
The L/S ratio indicates a 2:1 ratio of lecithin to sphingomyelin, which is an indicator of fetal lung maturity and occurs at approximately the middle of the third trimester. L/S ratios of 1.4:1, 1.8:1, and 1:1 each indicate immaturity of the fetal lungs.
11. A client arrives for her initial prenatal examination. This is her first child. She asks the nurse, “How does my baby get air inside my uterus?” What is the correct response by the nurse?
a. “The baby’s 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 baby’s abdomen.”
The placenta delivers oxygen-rich blood through the umbilical vein, not the artery, to the fetus and excretes carbon dioxide into the maternal bloodstream. The fetal lungs do not function as respiratory gas exchange in utero. The baby does not simply absorb oxygen from a woman’s blood system; rather, blood and gas transport occur through the placenta.
12. What is the most basic information that a nurse should be able to share with a client who asks about the process of conception?
a. Ova are considered fertile 48 to 72 hours after ovulation.
b. Sperm remain viable in the woman’s 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.
After implantation, the endometrium is called the decidua. Ova are considered fertile for approximately 24 hours after ovulation. Sperm remain viable in the woman’s 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.
13. The maternity nurse is cognizant of what important structure and function of the placenta?
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.
The placenta produces four hormones necessary to maintain the pregnancy: hCG, hPL, estrogen, and progesterone. The placenta widens until 20 weeks of gestation 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.
14. Which statement regarding the development of the respiratory system is a high priority for the nurse to understand?
a. The respiratory system does not begin developing until after the embryonic stage.
b. The infant’s lungs are considered mature when the L/S ratio is 1:1, at approximately 32 weeks of gestation.
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 of gestation.
A reduction in placental blood flow stresses the fetus, increases blood levels of corticosteroids, and thus accelerates lung maturity. The development of the respiratory system begins during the embryonic phase and continues into childhood. The infant’s lungs are considered mature when the L/S ratio is 2:1, at approximately 35 weeks of gestation. Lung movements have been visualized on ultrasound scans at 11 weeks of gestation.
15. The various systems and organs of the fetus develop at different stages. Which statement is most accurate?
a. 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 of gestation.
c. Body changes from straight to C-shape occurs at 8 weeks of gestation.
d. Gastrointestinal system is mature at 32 weeks of gestation.
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 of gestation. The gastrointestinal system is complete at 36 weeks of gestation.
16. Which statement concerning neurologic and sensory development in the fetus is correct?
a. Brain waves have been recorded on an electroencephalogram as early as the end of the first trimester (12 weeks of gestation).
b. Fetuses respond to sound by 24 weeks of gestation and can be soothed by the sound of the mother’s voice.
c. Eyes are first receptive to light at 34 to 36 weeks of gestation.
d. At term, the fetal brain is at least one third the size of an adult brain.
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 of gestation. The fetal brain is approximately one fourth the size of an adult brain.
17. A woman’s cousin gave birth to an infant with a congenital heart anomaly. The woman asks the nurse when such anomalies occur during development. Which response by the nurse is most accurate?
a. “We don’t really know when such defects occur.”
b. “It depends on what caused the defect.”
c. “Defects occur between the third and fifth weeks of development.”
d. “They usually occur in the first 2 weeks of development.”
The cardiovascular system is the first organ system to function in the developing human. Blood vessel and blood formation begins in the third week, and the heart is developmentally complete in the fifth week. “We don’t really know when such defects occur” is an inaccurate statement. Regardless of the cause, the heart is vulnerable during its period of development—in the third to fifth weeks; therefore, the statement, “They usually occur in the first 2 weeks of development” is inaccurate.
18. Which information regarding amniotic fluid is important for the nurse to understand?
a. Amniotic fluid serves as a source of oral fluid and a repository for waste from the fetus.
b. Volume of the amniotic fluid remains approximately the same throughout the term of a healthy pregnancy.
c. The study of fetal cells in amniotic fluid yields little information.
d. A volume of more than 2 L of amniotic fluid is associated with fetal renal abnormalities.
Amniotic fluid serves as a source of oral fluid, serves as a repository for waste from the fetus, cushions the fetus, and helps maintain a constant body temperature. The volume of amniotic fluid constantly changes. The study of amniotic fluid yields information regarding the sex of the fetus and the number of chromosomes. Too much amniotic fluid (hydramnios) is associated with gastrointestinal and other abnormalities.
19. An expectant couple attending childbirth classes have questions regarding multiple births since twins “run in the family.” What information regarding multiple births is important for the nurse to share?
a. Twinning and other multiple births are increasing because of the use of fertility drugs and delayed childbearing.
b. Dizygotic twins (two fertilized ova) have the potential to be conjoined twins.
c. Identical twins are more common in Caucasian families.
d. Fraternal twins are the same gender, usually male.
If the parents-to-be are older and have taken fertility drugs, then they would be very interested to know about twinning and other multiple births. Conjoined twins are monozygotic; that is, they are from a single fertilized ovum in which division occurred very late. Identical twins show no racial or ethnic preference, and fraternal twins are more common among African-American women. Fraternal twins can be different genders or the same gender, and identical twins are the same gender.
20. The nurse caring for a pregnant client is evaluating his or her health teaching regarding fetal circulation. Which statement from the client reassures the nurse that his or her teaching has been effective?
a. “Optimal fetal circulation is achieved when I am in the side-lying position.”
b. “Optimal fetal circulation is achieved when I am on my back with a pillow under my knees.”
c. “Optimal fetal circulation is achieved when the head of the bed is elevated.”
d. “Optimal fetal circulation is achieved when I am on my abdomen.”
Optimal circulation is achieved when the woman is lying at rest on her side. Decreased uterine circulation may lead to intrauterine growth restriction. Previously, it was believed that the left lateral position promoted maternal cardiac output, enhancing blood flow to the fetus. However, it is now known that the side-lying position enhances uteroplacental blood flow. If a woman lies on her back with the pressure of the uterus compressing the vena cava, then blood return to the right atrium is diminished. Although having the head of the bed elevated is recommended and ideal for later in pregnancy, the woman still must maintain a lateral tilt to the pelvis to avoid compressing the vena cava. Many women find lying on their abdomen uncomfortable as pregnancy advances. Side-lying is the ideal position to promote blood flow to the fetus.
21. Some of the embryo’s intestines remain within the umbilical cord during the embryonic period. What is the rationale for this development of the gastrointestinal system?
a. Umbilical cord is much larger at this time than it will be at the end of pregnancy.
b. Intestines begin their development within the umbilical cord.
c. Nutrient content of the blood is higher in this location.
d. Abdomen is too small to contain all the organs while they are developing.
The abdominal contents grow more rapidly than the abdominal cavity; therefore, part of their development takes place in the umbilical cord. By 10 weeks of gestation, the abdomen is large enough to contain them. Intestines begin their development within the umbilical cord but only because the liver and kidneys occupy most of the abdominal cavity. Blood supply is adequate in all areas.
22. A woman is 15 weeks pregnant with her first baby. She asks how long it will be before she feels the baby move. What is the nurse’s best answer?
a. “You should have felt the baby move by now.”
b. “Within the next month, you should start to feel fluttering sensations.”
c. “The baby is moving; however, you can’t feel it yet.”
d. “Some babies are quiet, and you don’t feel them move.”
Maternal perception of fetal movement usually begins 16 to 20 weeks after conception. Because this is her first pregnancy, movement is felt toward the later part of the 16- to 20-week time period. Stating, “you should have felt the baby move by now” is incorrect and may be an alarming statement to the client. Fetal movement should be felt by 16 to 20 weeks. If movement is not felt by the end of that time, then further assessment is necessary.
23. A new mother asks the nurse about the “white substance” covering her infant. How should the nurse explain the purpose of vernix caseosa?
a. Vernix caseosa protects the fetal skin from the amniotic fluid.
b. Vernix caseosa promotes the normal development of the peripheral nervous system.
c. Vernix caseosa allows the transport of oxygen and nutrients across the amnion.
d. Vernix caseosa regulates fetal temperature.
Prolonged exposure to the amniotic fluid during the fetal period could result in the breakdown of the skin without the protection of the vernix caseosa. Normal development of the peripheral nervous system was dependent on nutritional intake of the mother. The amnion was the inner membrane that surrounded the fetus and was not involved in the oxygen and nutrient exchange. The amniotic fluid helped maintain fetal temperature.
24. A woman who is 16 weeks pregnant asks the nurse, “Is it possible to tell by ultrasound if the baby is a boy or girl yet?” What is the best answer?
a. “A baby’s sex is determined as soon as conception occurs.”
b. “The baby has developed enough to enable us to determine the sex by examining the genitals through an ultrasound scan.”
c. “Boys and girls look alike until approximately 20 weeks after conception, and then they begin to look different.”
d. “It might be possible to determine your baby’s sex, but the external organs look very similar right now.”
Although gender is determined at conception, the external genitalia of males and females look similar through the ninth week. By the twelfth week, the external genitalia are distinguishable as male or female.
25. Which development related to the integumentary system is correct?
a. Very fine hairs called lanugo appear at 12 weeks of gestation.
b. Eyelashes, eyebrows, and scalp hair appear at 28 weeks of gestation.
c. Fingernails and toenails develop at 28 weeks of gestation.
d. By 32 weeks, scalp hair becomes apparent.
Very fine hairs, called lanugo appear first at 12 weeks of gestational age on the fetus’ eyebrows and upper lip. By 20 weeks of gestation, lanugo covers the entire body. By 20 weeks of gestation the eyelashes, eyebrows, and scalp hair also begin to grow. By 28 weeks of gestation, the scalp hair is longer than these fine hairs, which is thin and may disappear by term. Fingernails and toenails develop from thickened epidermis, beginning during the 10th week. Fingernails reach the fingertips at 32 weeks of gestation, and the toenails reach the toe tips at 36 weeks of gestation.
26. The pancreas forms in the foregut during the 5th to 8th week of gestation. A client with poorly controlled gestational diabetes asks the nurse what the effects of her condition will be on the fetus. What is the best response by the nurse? Poorly controlled maternal gestational diabetes will:
a. produce fetal hypoglycemia.
b. result in a macrocosmic fetus.
c. result in a microcosmic fetus.
d. enhance lung maturation.
Insulin is produced by week 20 of gestation. In the fetus of a mother with uncontrolled diabetes, maternal hypoglycemia produces fetal hypoglycemia and macrocosmia results. Hyperinsulinemia blocks lung maturation, placing the neonate at risk for respiratory distress.
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 substances might be considered a teratogen? (Select all that apply.)
a. Cytomegalovirus (CMV)
b. Ionizing radiation
ANS: A, B, 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, 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 medications (e.g., carbamazepine) and some antibiotics, as well as chemicals including lead, mercury, tobacco, and alcohol, may also result in structural and functional abnormalities.
2. Relating to the fetal circulatory system, which special characteristics allow the fetus to obtain sufficient oxygen from the maternal blood? (Select all that apply.)
a. Fetal hemoglobin (Hb) carries 20% to 30% more oxygen than maternal Hb.
b. Fetal Hb carries 40% to 50% more oxygen than maternal Hb.
c. Hb concentration is 50% higher than that of the mother.
d. Fetal heart rate is 110 to 160 beats per minute.
e. Fetal heart rate is 160 to 200 beats per minute.
ANS: A, C, D
The following three special characteristics enable the fetus to obtain sufficient oxygen from maternal blood: (1) the fetal Hb carries 20% to 30% more oxygen; (2) the concentration is 50% higher than that of the mother; and (3) the fetal heart rate is 110 to 160 beats per minute, a cardiac output that is higher than that of an adult.
A woman’s cousin gave birth to an infant with a congenital heart anomaly. The woman asks the nurse when such anomalies occur during development. Which response by the nurse is most accurate?
a. “We don’t really know when such defects occur.”
b. “It depends on what caused the defect.”
c. “They occur between the third and fifth weeks of development.”
d. “They usually occur in the first 2 weeks of development.”
The nurse would be aware of when such defects occur. Regardless of the cause, the heart is vulnerable during its period of development, the third to fifth weeks. The cardiovascular system is the first organ system to function in the developing human. Blood vessel and blood formation begins in the third week, and the heart is developmentally complete in the fifth week.
A woman is 8 months pregnant. She tells the nurse that she knows her baby listens to her, but her husband thinks she is imagining things. Which response by the nurse is most appropriate?
a. “Many women imagine what their baby is like.”
b. “A baby in utero does respond to the mother’s voice.”
c. “You’ll need to ask the doctor if the baby can hear yet.”
d. “Thinking that your baby hears will help you bond with the baby.”
Fetuses respond to sound by 24 weeks. The fetus can be soothed by the sound of the mother’s voice, and the nurse should instruct the mother so. Although statement A is accurate, it is not the most appropriate response. Statement D is not appropriate because it gives the mother impression that her baby cannot hear her and belittles her interpretation of her fetus’s behaviors.
A maternity nurse should be aware of which fact about the amniotic fluid?
a. It serves as a source of oral fluid and as a repository for waste from the fetus.
b. The volume remains about the same throughout the term of a healthy pregnancy.
c. A volume of less than 300 ml is associated with gastrointestinal malformations.
d. A volume of more than 2 L is associated with fetal renal abnormalities.
Amniotic fluid also cushions the fetus and helps maintain a constant body temperature. Its volume changes constantly; too little fluid (oligohydramnios) is associated with renal abnormalities, and too much fluid (polyhydramnios) is associated with gastrointestinal and other abnormalities.
Many parents-to-be have questions about multiple births. Maternity nurses should be able to tell them that:
a. Rates of twinning and other multiple births are increasing because of the use of fertility drugs and delayed childbearing.
b. Dizygotic twins (two fertilized ova) have the potential to be conjoined twins.
c. Identical twins are more common in Caucasian families.
d. Fraternal twins are same gender, usually male.
If the parents-to-be are older and have taken fertility drugs, they would be very interested in this information. Conjoined twins are monozygotic; they are from a single fertilized ovum in which division occurred very late. Identical twins show no racial or ethnic preference; fraternal twins are more common among African-American women. Fraternal twins can be different genders or the same gender. Identical twins are the same gender.
The nurse caring for a pregnant woman knows that her health teaching regarding fetal circulation has been effective when the woman reports that she has been sleeping:
a. In a side-lying position.
b.On her back with a pillow under her knees.
c. With the head of the bed elevated.
d. On her abdomen.
Optimal circulation is achieved when the woman is lying at rest on her side. Decreased uterine circulation may lead to intrauterine growth restriction. Previously it was believed that the left lateral position promoted maternal cardiac output, thereby enhancing blood flow to the fetus. However, it is now known that either side-lying position enhances uteroplacental blood flow. If a woman lies on her back with the pressure of the uterus compressing the vena cava, blood return to the right atrium will be diminished. Although having a pillow under the knees is recommended and ideal for later in pregnancy, the woman must still maintain a lateral tilt to the pelvis to avoid compression of the vena cava. Many women will find lying on the abdomen uncomfortable as pregnancy advances.
A woman at 35 weeks of gestation has had an amniocentesis. The results reveal that surface-active phospholipids are present in the amniotic fluid. The nurse is aware that this finding indicates that:
a. The fetus is at risk for Down syndrome.
b. The woman is at high risk for developing preterm labor.
c. The lungs are mature.
d. Meconium is present in the amniotic fluid.
The detection of the presence of pulmonary surfactants, surface-active phospholipids, in amniotic fluid has been used to determine fetal lung maturity, or the ability of the lungs to function after birth. This occurs at approximately 35 weeks of gestation. This result is unrelated to Down syndrome and in no way indicates risk for preterm labor. Meconium should not be present in the amniotic fluid.
Which time span delineates the appropriate length for a normal pregnancy?
a. 9 lunar months, 8.5 calendar months, 39 weeks, 272 days
b. 10 lunar months, 9 calendar months, 40 weeks, 280 days
c. 9 calendar months, 10 lunar months, 42 weeks, 294 days
d. 9 calendar months, 38 weeks, 266 days
Pregnancy lasts approximately 10 lunar months, 9 calendar months, 40 weeks, 280 days. Length of pregnancy is computed from the first day of the last menstrual period (LMP) until the day of birth. Nine lunar months is just short of a term pregnancy, and 294 days is longer than the average length of a pregnancy and would be considered postterm. Because conception occurs approximately 2 weeks after the first day of the LMP, the length described in D represents the postconception age of 266 days or 38 weeks. Postconception age is used in the discussion of fetal development.
A pregnant woman has been diagnosed with oligohydramnios. Which presentation would the nurse suspect to find on physical examination?
a. Fetus is in a breech position
b. FHR baseline is within normal range
c. Fetus with possible renal problems
d. Increased fundal height
Oligohydramnios reflects a decrease in the amount of amniotic fluid and is associated with renal abnormalities in the fetus and compromised fetal well-being. The position of the fetus is due to gestational age and the maternal uterine environment. FHR may be within normal range because it is affected by gestational age and fetal well-being. An increase in fundal height would be associated with polyhydramnios and/or gestational age assessment.
Which developmental finding is accurate with regard to fetal growth?
a. Heart starts beating at 12 weeks.
b. Lungs take shape by 8 weeks.
c. Brain configuration is complete by 8 weeks.
d. Main blood vessels form by 8 weeks.
The heart starts beating by 4 weeks, the lungs take shape by 12 weeks, and brain configuration is complete by 12 weeks.