Chapter 3: Genetics, Conception, Fetal Development, and Reproductive Technology by Durham and Chapman, Chapter 15 Physiological and Behavioral Responses of the Neonate, Chapter 16 Discharge Planning and Teaching, Chapter 17 High-Risk Neonatal Nursing...

The postnatal nurse is making a newborn visit to the parents who are from a different country. The nurse finds the newborn swaddled in a heavy blanket and wearing a knitted cap. The newborn has wet hair and is restless with rapid breathing. Which initial comment from the nurse is appropriate?

"Share with me how babies are cared for in your country."

The nurse is collecting information from a new mother who is bottle-feeding her infant. Which comment, if made by the mother, requires the nurse to provide patient teaching?

"Sometimes I will add a little water to the formula if I am running low."

The clinic nurse recognizes that pregnant women who are in particular need of support are those who (select all that apply):

-Are awaiting genetic testing results -Are trying to conceal this pregnancy as long as possible A second pregnancy is not an indication of a woman in need of additional support. A support system may be lacking for women who are trying to conceal a pregnancy or for women who are trying to keep the news of their pregnancy from relatives or friends until results from genetic tests are known. These individuals may need additional support from their nurses and other health-care providers, as they are placed in a powerless situation while awaiting results and face a pregnancy that may be in jeopardy.

A woman seeks care at an infertility clinic. Which of the following tests may this woman undergo to determine what, if any, infertility problem she may have? (Select all that apply.)

-Endometrial biopsy -Hysterosalpingogram -Serum FSH analysis b. Endometrial biopsy is performed about 1 week following ovulation to detect the endometrium's response to progesterone. c. Hysterosalpingogram is used to determine if fallopian tubes are patent. d. Serum FSH levels are used to assess ovarian function.

Which of the following places a couple at higher risk for conceiving a child with a genetic abnormality? (Select all that apply.)

-Maternal age over 35 years -Partner who has a genetic disorder Fertility decreases after 35 years. A partner contributes half of the chromosomal makeup, and genetic disorders can be inherited. Maternal diabetes can have an effect on the fetus/neonate, such as causing complications such as macrosomia and hypoglycemia, but these are not genetic disorders. Paternal heart disease can place the neonate at risk for heart disease later in life, but this is not referred to as a genetic disorder, such as is trisomy 21 and hemophilia.

A couple is undergoing an infertility workup. The semen analysis indicates a decreased number of sperm and immature sperm. Which of the following factors can have a potential effect on sperm maturity? (Select all that apply.)

-The man rides a bike to and from work each day. -The man takes a calcium channel blocker for the treatment of hypertension. The daily riding of a bike can be the cause of prolonged heat exposure to the testicles. Prolonged heat exposure is a gonadotoxin. A number of medications, such as calcium channel blockers, can have an effect on sperm production. Coffee has not been associated with low sperm counts. Prostatitis or other infections within the last 3 months may have an effect on the sperm analysis. This man's episode of prostatitis was 12 months prior.

A clinic nurse explains to the pregnant woman that the amount of amniotic fluid present at 24 weeks' gestation is approximately:

800 mL Amniotic fluid first appears at about 3 weeks. There are approximately 30 mL of amniotic fluid present at 10 weeks' gestation, and this amount increases to approximately 800 mL at 24 weeks' gestation. After that time, the total fluid volume remains fairly stable until it begins to decrease slightly as the pregnancy reaches term.

____________________ is a chronic lung problem that affects neonates who have been treated with mechanical ventilation and oxygen for problems such as RDS.

Bronchopulmonary dysplasia

The nurse is concerned about the number of infants in the community who die from SIDS even with teaching about "back to sleep" being provided. On which additional preventive measures will the nurse focus? Select all that apply.

During pregnancy, women should not smoke, drink alcohol, or use illegal drugs. Infants need to be dressed to prevent infants from overheating during sleep. Mothers need to be informed that breastfeeding reduces the risk for SIDS. Parents should not smoke or allow smoking around their baby. Parents need to avoid products that claim to reduce the risk of SIDS.

The postpartum nurse-manager wants the unit to become active as a supporter of the Baby-Friendly Hospital Initiative. Which nursing actions will be initiated? Select all that apply.

Help mothers initiate breastfeeding within 1 hour of birth. Teach breastfeeding and promote lactation to mothers separated from infants. Refer mothers to support group resources on discharge.

A patient in the first stage of pregnancy is discussing the options for feeding her infant, and asks the nurse, "Which is the most important reason I should consider breastfeeding my baby?" Which is the most significant reason the nurse presents?

Human milk contains multiple antibodies, enzymes, and immune factors.

The postnatal nurse is providing care for a neonate being treated with phototherapy for hyperbilirubinemia. For which side effects of phototherapy will the nurse contact the neonatal care provider? Select all that apply.

Hyperthermia Hypocalcemia Thrombocytopenia

A diagnostic test commonly used to assess problems of the fallopian tubes is:

Hysterosalpingogram Correct. Hysterosalpingogram provides information on the endocervical canal, uterine cavity, and fallopian tubes.

The nurse is teaching newborn care to an adolescent mother. When the nurse attempts to teach how to swaddle the newborn, the mother states, "What's the big deal about how to wrap up a baby?" The nurse needs to convey which reason as being most important for proper swaddling?

Improper swaddling can cause hip dysplasia.

The nurse is preparing for the discharge of a premature neonate to home with the parents. The nurse explains the neonate must be able to pass the infant car seat challenge before discharge. For which reason would the neonate be considered unsafe in a car seat?

Inability to maintain adequate oxygenation, heart rate, and respiratory rate during trial

A woman at 40 weeks' gestation has a diagnosis of oligohydramnios. Which of the following statements related to oligohydramnios is correct?

It indicates that there is a 50% reduction of amniotic fluid. Correct. Oligohydramnios refers to a decreased amount of amniotic fluid of less than 500 mL at term or 50% reduction of normal amounts.

A neonate is born after 37 weeks gestation, and the nurse is concerned about avoiding cold stress after discharge. Which suggestions does the nurse give the mother to keep the baby safe? Select all that apply.

Keep the baby wrapped in a warm blanket. Position the baby away from vents and drafts. Place a stocking cap on the neonate's head. Change wet clothing immediately.

The nurse is providing care for a neonate born to a mother with preexisting diabetes mellitus. Which neonatal assessment findings do the nurse expect? Select all that apply.

Macrosomia Hypocalcemia Jaundice Dyspnea

The nurse is providing care for a premature neonate in the NICU nursery. The neonate is diagnosed with bronchopulmonary dysplasia (BPD) and patent ductus arteriosus (PDA). Which specific intervention does the nurse expect for this neonate?

Maintain fluid restrictions.

The nurse is providing support to a mother whose newborn is diagnosed with a life-threatening defect. The mother states, "I just want to go home and never come back." Which reaction by the mother does the nurse recognize?

Maternal emotional distancing

The labor and delivery nurse understands that some neonates spontaneously take a breath once the head and chest is delivered. Which understanding does the nurse have for the neonate that requires chemical stimuli to breathe?

Mild hypoxia and decreased pH stimulates the brain.

A new mother expresses severe frustration with an infant that is exhibiting symptoms of colic. Which suggestions from the nurse are aimed at infant safety? Select all that apply.

Place the baby in a safe place and allow the baby to cry for 10 to 15 minutes. Do simple household chores, such as vacuuming or washing the dishes.

A nurse is teaching a woman about her menstrual cycle. The nurse states that __________ is the most important change that happens during the secretory phase of the menstrual cycle.

Proliferation of the endometrium The proliferation of the endometrium occurs during the secretory phase of the menstrual cycle.

The parents of a newborn male are concerned about providing care for the baby's new circumcision performed with a Plastibell. Which information will the nurse include in the teaching plan for the parents?

Report if penis is red, warm, and swollen and/or there is surgical site drainage.

The nurse is preparing for the discharge of a neonate diagnosed with a congenital breathing disorder. Which health team members does the nurse include in discharge planning? Select all that apply.

Respiratory therapist Social worker Home health agency nurse Case manager

The clinic nurse knows that the part of the endometrial cycle occurring from ovulation to just prior to menses is known as the:

Secretory phase The secretory phases occurs from the time of ovulation to the period just prior to menses, or approximately days 15 to 26. (SEX PRIOR TO MENSES)

The nurse takes the history of a client, G2 P1, at her first prenatal visit. The client is referred to a genetic counselor, due to her previous child having a diagnosis of __________.

Sickle cell anemia Sickle cell anemia is an autosomal recessive illness. This client needs to be seen by a genetic counselor.

A client is to take Clomiphene Citrate for infertility. Which of the following is the expected action of this medication?

Stimulate release of FSH and LH Clomiphene Citrate stimulates release of FSH and LH.

A major fetal development characteristic at 16 weeks' gestation is:

Teeth begin to form

The nurse is explaining to a mother that her newborn's blood test indicates a high level of unconjugated bilirubin, which causes jaundice. Which information does the nurse present to the mother? Select all that apply.

The blood test does not indicate a pathological disease. The newborn's liver converts bilirubin to a water-soluble substance. An abundance of RBCs and RBC short life span contributes to the condition. Elevated bilirubin can be excreted in the urine and stool.

A nurse working with an infertile couple has made the following nursing diagnosis: Sexual dysfunction related to decreased libido. Which of the following assessments is the likely reason for this diagnosis?

The couple has established a set schedule for their sexual encounters. Couples who "schedule" intercourse often complain that their sexual relationship is unsatisfying.

A mother of a premature neonate in NICU asks the nurse when her baby will begin getting oral feedings. The nurse is aware that multiple conditions are desired. Which condition is most essential?

The neonate exhibits cardiorespiratory regulation.

The postpartum nurse notices that a new mother has her neonate unwrapped and undressed "to check out the baby." For which reason does the nurse conclude the neonate is at risk for cold stress?

The neonate is moving extremities about.

The nurse works in a postnatal nursery and is required by hospital policy to perform a gestational age assessment on specified neonates. On which neonate is the nurse most likely to perform this assessment?

The neonate with a birth weight of 4,100 g

The lactation nurse visits the room of a patient who is postpartum and being prepared for discharge. The nurse plans to provide breastfeeding information aimed at assisting the patient to continue breastfeeding her newborn. Which observation by the nurse indicates a possible disruption to the planned teaching?

The patient is excited about taking her baby home.

A couple who has sought infertility counseling has been told that the man's sperm count is very low. The nurse advises the couple that spermatogenesis is impaired when which of the following occur?

The testes are overheated. Spermatogenesis occurs in the testes. High temperatures harm the development of the sperm.

Which information is important for the nurse to provide to mothers of infants of 3 months of age regardless of the method of infant feeding?

When growth spurts and dietary increases are expected

The nurse is teaching new parents about the Period of PURPLE Crying Program aimed at the prevention of shaken baby syndrome. At the end of the program, the nurse evaluates the program successful if parents select which fact? Select all that apply.

Your baby may not stop crying no matter what you do. Your baby may cry more in the late afternoon and evening. A crying baby may look to be in pain, even when he or she is not.

The nurse is assessing a newborn's reflexes. Which response will cause the nurse concern?

Asymmetrical Moro reflex

The nurse is teaching the mother of a neonate the benefits of kangaroo care. Which action is explained to the mother regarding the procedure?

A bare-chested neonate is held against a bare-chested parent.

Postnatal nurses expressed concern about neonatal pain management during painful interventions. Using evidence-based practice from research performed by Thakkar, Arora, Das, Javadekar, and Panigrahi (2016), which method of pain control will be used for heel sticks?

A combination of stimulated sucking and receiving sucrose orally.

An ultrasound of a fetus' heart shows that "normal fetal circulation is occurring." Which of the following statements is consistent with the finding?

A right to left shunt is seen between the atria. This is correct. The foramen ovale is a duct between the atria. In fetal circulation, there is a right to left shunt through the duct.

The nurse is assisting a newborn's primary care provider with the performance of a circumcision. Which intervention is used to manage the neonate's pain?

A sucrose-dipped pacifier is offered during the nerve block.

The nurse is preparing a talk with new parents about immunity and their newborns. Which factual information will the nurse present? Select all that apply.

A vaccination is an example of acquired immunity. Placental transfer is how newborns get natural passive immunity. Natural passive immunity protects the baby for a few months after birth.

The nurses in a postnatal unit are aware of the fears of new parents with regard to infant abduction. Which interventions by the nurse will alleviate the concerns of the parents? Select all that apply.

Allow only visitors with identification to enter the unit. Use the hospital abduction alarm systems. Require unit personnel to wear specific name tags. Footprints and a photo of the neonate are taken for identification purposes. Encourage parents to accompany persons transporting the newborn.

The nurse is present in the delivery room when a mother is told her neonate was stillborn. The mother begins to wail loudly and pull at her hair. Which action does the nurse take?

Allow the mother to express grief in her own way.

The nurse in the neonate nursery notices a neonate, born 45 minutes ago, is unresponsive to external stimuli, and has a respiratory and heart rate below normal range. Which action does the nurse take?

Allows the neonate to naturally continue deep sleep.

The nurse in NICU is assessing a neonate delivered at 32 weeks gestation. Which pathophysiological manifestation is the nurse's greatest concern?

Apnea 20 seconds or longer

The nurse is interviewing a gravid woman during the first prenatal visit. The woman confides to the nurse that she lives with a number of pets. The nurse should advise the woman to be especially careful to refrain from coming in contact with the stool of which of the pets?

Cat The patient should refrain from coming in direct contact with cat feces. Cats often harbor toxoplasmosis, a teratogenic illness.

Information provided by the nurse that addresses the function of the amniotic fluid is that the amniotic fluid helps the fetus to maintain a normal body temperature and also:

Cushions the fetus from mechanical injury Amniotic fluid cushions the fetus from mechanical injury.

The postpartum nurse is preparing to present infant care information to a couple who expresses concern about when to bathe their newborn. Which behaviors will the nurse present as general guidelines? Select all that apply.

Daily bathing with soap is not necessary for the newborn. Use a mild preservative-free soap with a neutral pH. Avoid the use of soap on the face of the newborn. Genital and rectal areas should be cleaned at each diaper change.

The nurse is preparing to teach a class on the benefits of breastfeeding for infants. Which benefits will the nurse include in the presentation? Select all that apply.

Decreased incidence of SIDS Fewer cases of necrotizing enterocolitis Decreased risk for developing otitis media

During the fourth stage of labor, which actions by the nurse will promote parent-newborn attachment? Select all that apply.

Delay administration of eye ointment until parents have held newborn. Initiate skin-to-skin contact with a warm blanket over the neonate and parent. Explain expected neonatal characteristics such as molding, milia, and lanugo.

The nurse is providing support for the parents of a neonate born with anencephaly. The parents repeatedly state, "I don't believe this is happening to us. We were so careful during pregnancy." The nurse associates the parents' comments with which stage of grief?

Disbelief

The nurse is providing care for a neonate during the fourth stage of labor. Which action does the nurse take during this stage?

Dry the neonate immediately.

3. The fetal circulatory structure that connects the pulmonary artery with the descending aorta is known as which of the following?

Ductus arteriosus

A mother who is breastfeeding expresses concern about whether her infant is getting enough milk. Which concrete indicator does the nurse provide to the mother?

There are at least eight wet diapers and several stools per day.

A patient in the second trimester of pregnancy is discussing breastfeeding and other options with the nurse. Which question is most important for the nurses to ask?

"How does your partner feel about you breastfeeding?"

The nurse is collecting information from a parent whose infant has frequent diaper dermatitis. Which comment by the parent indicates a possible cause of the condition? Select all that apply.

"I buy an antibiotic ointment specified for skin rashes."

The nurse is providing information to a postpartum mother about circumcision of her neonate. The neonate's father states, "We have never done that to any baby boy in my family." Which statement is best for the nurse to make?

"I understand that family culture and beliefs form our way of life."

Which of the following statements by a pregnant woman indicates she needs additional teaching on ways to reduce risks to her unborn child from the potential effects of exposure to toxoplasmosis?

"I will wear a mask when cleaning my cat's litter box." Correct. Pregnant women and women who are attempting pregnancy should avoid contact with cat feces. Exposure occurs when the protozoan parasite found in cat feces and uncooked or rare beef and lamb is ingested. Wearing a mask will not decrease the risk through ingestion of the parasite.

A new mother states, "I don't want anyone around my baby. I need to protect him from getting sick." Which statement by the nurse will help the mother to understand neonatal immunity? Select all that apply.

"The baby has natural passive immunity from you for a few months." "We will give the baby gamma globin for short-term immediate protection."

A couple who has been attempting to become pregnant for 5 years is seeking assistance from an infertility clinic. The nurse assesses the clients' emotional responses to their infertility. Which of the following responses would the nurse expect to find? (Select all that apply.)

-Anger at others who have babies. -Feelings of failure because they cannot make a baby. -Guilt on the part of one partner because he or she is unable to give the other a baby. a. Infertile couples often feel anger toward couples who have babies. b. Infertile couples often express feelings of personal failure. d. Guilt is often expressed by the couple.

The ovarian cycle includes which of the following phases? (Select all that apply.)

-Follicular phase -Ovulatory phase -Luteal phase Follicular phase, ovulatory phase, and luteal phase are part of the ovarian cycle. Secretory and menstrual phases are part of the endometrial cycle.

During preconception counseling, the clinic nurse explains that the time period when the fetus is most vulnerable to the effects of teratogens occurs from:

2 to 8 weeks The period of organogenesis lasts from approximately the second until the eighth week of gestation during which time the embryo undergoes rapid growth and differentiation. During organogenesis, the embryo is extremely vulnerable to teratogens such as medications, alcohol, tobacco, caffeine, illegal drugs, radiation, heavy metals, and maternal (TORCH) infections. Structural fetal defects are most likely to occur during this period because exposure to teratogens either before or during a critical period of development of an organ can cause a malformation.

The nurse notices that a neonate being treated for hyperbilirubinemia with phototherapy has had a daily increase of total bilirubin serum levels greater than 5 mg/dL for the past 2 days. The neonatal care provider prescribes an exchange transfusion. Which knowledge does the nurse apply to the procedure?

Approximately 85% of the neonate's RBCs are replaced.

The nurse is providing support to parents of a premature neonate in NICU. Which actions by the nurse will best provide psychosocial support to the parents? Select all that apply.

Ask the parents how they are coping with the experience. Encourage parents to take photos to share with family and friends. Praise parents for their involvement in the care of their neonate.

A breastfeeding mother is planning to return to work 3 months after her baby is born. The mother is planning to use an electric breast pump and freeze some breast milk for use later. Which information does the nurse need to provide?

Breast milk can be kept in a deep freezer for 6 to 12 months.

The NICU nurse encourages the mother of a premature neonate to bring breast milk to the unit for enteral feedings to her baby. For which reason does the nurse make this suggestion?

Breast milk helps prevent necrotizing enterocolitis.

. __________ __________ __________ is when sperm and oocytes are mixed outside the woman's body and then placed into the fallopian tube via laparoscopy.

Gamete intrafallopian transfer Gamete intrafallopian transfer, also referred to as GIFT, is used when there is a history of failed infertility treatment for anovulation, or unexplained infertility, or low sperm count.

The nurse is explaining to the new breastfeeding mother the types of neonatal stools the mother can expect. Which examples does the nurse provide? Select all that apply.

Golden yellow, a pasty consistency, and sour odor is expected. Neonate's first stool is passed within the first 24 to 48 hours.

The nurse is assessing a term neonate delivered to a mother with a history of drug and alcohol abuse. Which finding does the nurse relate to the mother's history?

Head circumference is below the 10th percentile of normal for gestational age.

A mother who is 2 weeks postpartum asks the nurse lactation specialist how she knows if her baby is hungry. Which hunger indicator does the nurse discuss?

Opening the mouth in response to tactile stimulation

The nurses in a NICU are concerned about the appropriate levels of oxygen therapy during the care of premature neonates. The nurses referenced an article by Newman (2014) titled, "Oxygen Saturation Limits and Evidence supporting the Targets." On which evidence-based conclusion will the nurses develop guidelines?

Oxygen saturation limits need to be between 87% to 94%.

The nurse is providing care for a premature neonate born at 28 weeks gestation who is experiencing respiratory distress syndrome (RDS). Which assessment finding indicates to the nurse that the neonate's respiratory status is deteriorating?

Pao2 is 48 and Paco2 is 55 mm Hg on 90% oxygen.

The color of a person's hair is an example of which of the following?

Phenotype Correct. Phenotype refers to how genes are outwardly expressed, such as eye color, hair color, and height.

The labor and delivery nurse is present for the delivery of a premature neonate. Which action by the nurse is most important?

Provide a neutral temperature environment.

A patient who is at 41 weeks gestation is concerned when the primary care provider decides to induce labor. Which reason does the nurse explain as the most important need for this procedure?

Risk for placental dysfunction

The nurse is presenting information to new parents regarding screening of their newborn. Which information does the nurse identify as being most important to the parents?

Screenings are for infections, genetic diseases, and inherited disorders.

Karen, a 26-year-old woman, has come for preconception counseling and asks about caring for her cat as she has heard that she "should not touch the cat during pregnancy." The clinic nurse's best response is:

Toxoplasmosis is a concern during pregnancy, so it is important to have someone else change the cat's litter pan and also to avoid consuming uncooked meat. Women need to be aware that Toxoplasma gondii, a single-celled parasite, is responsible for the infection toxoplasmosis. The majority of individuals who become infected with toxoplasmosis are asymptomatic, although when present, symptoms are described as "flu like" and include glandular pain and enlargement and myalgia. Severe toxoplasmosis infection may cause damage to the fetal brain, eyes, or other organs. Toxoplasmosis is usually acquired by consuming raw or poorly cooked meat that has been contaminated with T. gondii. Toxoplasmosis may also be acquired through close contact with feces from an infected animal (usually cats) or soil that has been contaminated with T. gondii.

True/False: The perinatal nurse explains to the student nurse that in the fetal circulation, the lowest level of oxygen concentration is found in the umbilical arteries.

True The highest oxygen concentration (PO2 = 30-35 mm Hg) is found in the blood returning from the placenta via the umbilical vein; the lowest oxygen concentration occurs in blood shunted to the placenta where reoxygenation takes place. The blood with the highest oxygen content is delivered to the fetal heart, head, neck, and upper limbs, and the blood with the lowest oxygen content is shunted toward the placenta.

The premature neonate is more susceptible to skin breakdown than a term neonate. Which skin care interventions will the nurse implement for the premature neonate? Select all that apply.

Use a neutral pH cleanser and sterile water for bathing. Gently apply emollients to avoid unnecessary friction. Use water, air, or gel mattresses.

A patient delivers a term neonate and expresses concern about the reason for giving the neonate an injection. Which information from the nurse is accurate?

Vitamin K is needed to activate clotting factors.

During prenatal class, the childbirth educator describes the two membranes that envelop the fetus. The __________ contains the amniotic fluid, and the __________ is the thick, outer membrane.

amnion; chorion The embryonic membranes (chorion and amnion) are early protective structures that begin to form at the time of implantation. The thick chorion, or outer membrane, forms first. It develops from the trophoblast and encloses the amnion, embryo, and yolk sac. The amnion arises from the ectoderm during early embryonic development. The amnion is a thin, protective structure that contains the amniotic fluid. With embryonic growth, the amnion expands and comes into contact with the chorion. The two fetal membranes are slightly adherent and form the amniotic sac.

The perinatal nurse is teaching nursing students about fetal circulation and explains that fetal blood flows through the superior vena cava into the right __________ via the __________.

atrium; foramen ovale Blood flows through the vein from the placenta to the fetus. Most of the blood bypasses the liver and then enters the inferior vena cava by way of the ductus venosus, a vascular channel that connects the umbilical vein to the inferior vena cava. The blood then empties into the right atrium, passes through the foramen ovale (an opening in the septum between the right and left atrium) into the left atrium, and then moves into the right ventricle and on into the aorta. From the aorta, blood travels to the head, upper extremities, and lower extremities.

The perinatal nurse explains to the student nurse that the growing embryo is called a __________ beginning at 8 weeks of gestational age.

fetus Major organs are being formed (organogenesis) during the first weeks following fertilization. During this time, the developing organism is called an embryo. By the end of 8 weeks, the embryo has sufficiently developed to be called a fetus.

After birth, the perinatal nurse explains to the new mother that __________ is the hormone responsible for stimulating milk production.

prolactin Following birth and delivery of the placenta, there is an abrupt decrease in estrogen. This event triggers an increased secretion of prolactin (the hormone that stimulates milk production) by the anterior pituitary gland. The posterior pituitary and hypothalamus play a role in the production and secretion of oxytocin, a hormone that causes release of milk from the alveoli.

During an initial assessment of the neonate's skin the nurse notices the presence of red marks called ____________________ on the neonate's eyelid and upper lip.

stork bites

The perinatal nurse defines a __________ as any substance that adversely affects the growth and development of the embryo/fetus.

teratogen Teratogens (drugs, radiation, and infectious agents that can cause development of abnormal structures in an embryo) and a variety of internal and external developmental events may cause structural and functional defects.