A father and mother are carriers of phenylketonuria (PKU). Their 2-year-old daughter has PKU. The couple tells the nurse that they are planning to have a second baby. Because their daughter has PKU, they are sure that their next baby won't be affected. What response by the nurse is most accurate?

Correct Answer: C

Rationale: The correct answer is C) You are both carriers, so each baby has a 25% chance of being affected. This response is accurate because phenylketonuria (PKU) is an autosomal recessive genetic disorder, meaning that both parents must carry the gene for their child to have the condition. With each pregnancy, there is a 25% chance that the child will inherit two copies of the gene and have PKU. Option A is incorrect because it misleads the couple into thinking that having a second child will not be affected by PKU, which is not true. Option B is not as direct as option C in explaining the genetic probability of the condition. Option D is incorrect as it provides irrelevant information about the baby's gender, which does not impact the inheritance of PKU. Educationally, understanding the principles of genetic inheritance is crucial for healthcare providers, especially when counseling families about the risks of passing on genetic conditions to their children. It is essential to communicate this information clearly and accurately to empower families to make informed decisions about their reproductive choices.

Correct Answer: D

Rationale: The correct answer, D, states that the risk factor for genetic disorders remains the same no matter how many affected children are already in the family. This is because the probability of inheriting a genetic disorder does not change based on the number of affected children in the family. Each child has an independent chance of inheriting the disorder, and the presence of affected siblings does not increase or decrease the risk for subsequent children. Option A is incorrect because the likelihood of a second child having a dominant disorder is not always 100%. Dominant disorders have a 50% chance of being passed on to each child, regardless of the presence of a previous affected child. Option B is incorrect as well because an autosomal recessive disease typically carries a one in four risk for each child, not one in eight. This is based on the probability of inheriting two recessive alleles, one from each parent. Option C is incorrect as it oversimplifies the recurrence risk for disorders involving maternal drug ingestion. The risk can vary depending on the specific drug, timing of exposure, and individual genetic factors. Understanding the principles of genetic inheritance and recurrence risks is crucial for nurses caring for families with genetic disorders. By knowing the correct probabilities and factors influencing recurrence, nurses can provide accurate information and support to families dealing with genetic conditions.

Correct Answer: C

Rationale: The correct answer is option C) "Babies respond to sound starting at about 24 weeks of gestation." This response is accurate because by 24 weeks of gestation, the fetus's auditory system is developed enough to perceive sound stimuli. Research indicates that fetuses can start responding to sound around this time, so the mother feeling the baby jump in response to a loud noise is plausible. Option A) "That must have been a coincidence; babies can't respond like that," is incorrect because fetal response to sound is a well-documented phenomenon supported by scientific evidence. Option B) "The fetus is demonstrating the aural reflex," is incorrect because there is no specific "aural reflex" recognized in fetal development. Option D) "Let me know if it happens again; we need to report that to your midwife," is incorrect as it does not address the developmental aspect of fetal response to sound. Educationally, understanding fetal development and behaviors is crucial for healthcare professionals working with pregnant women. Knowing the timeline of when fetuses begin to respond to sound helps in providing anticipatory guidance to expectant mothers and assessing fetal well-being during prenatal care.

Correct Answer: D

Rationale: The correct answer is D) Chorionic villi. Chorionic villi are finger-like projections that develop from the chorion, which is a membrane surrounding the embryo. These villi contain fetal blood vessels that are in close contact with the maternal blood in the uterus. This close proximity allows for the exchange of oxygen and carbon dioxide between the mother's bloodstream and the developing fetus. This process is crucial for the fetus to receive oxygen for survival and to eliminate carbon dioxide, which is a waste product of cellular respiration. Decidua basalis (option A) is the part of the endometrium where the chorionic villi implant and interact with maternal tissues, but it is not directly involved in oxygen and carbon dioxide transport. The blastocyst (option B) is an early stage of embryonic development and does not play a role in oxygen and carbon dioxide transport. The germ layer (option C) refers to the three primary layers of cells in the developing embryo but is not specifically responsible for oxygen and carbon dioxide transport. Understanding the role of chorionic villi in oxygen and carbon dioxide transport is essential in understanding the process of fetal development and the importance of the placenta in maintaining a healthy environment for the growing fetus. This knowledge is fundamental for healthcare professionals working in obstetrics and maternal-fetal medicine to ensure the well-being of both mother and baby during pregnancy.

Correct Answer: D

Rationale: The correct answer is D) Implantation in the endometrium occurs 6 to 10 days after conception. This is the most basic information a maternity nurse should know about conception because it highlights the timeline of events following fertilization. After conception, the fertilized egg undergoes several divisions as it travels down the fallopian tube towards the uterus. Implantation occurs when this developing embryo attaches to the thickened lining of the uterus, known as the endometrium. Option A is incorrect because ova are typically fertile for about 12-24 hours after ovulation, not 48 to 72 hours. Option B is also incorrect as sperm can remain viable in the female reproductive tract for up to 5 days, not just 12 to 24 hours. Option C is incorrect as conception actually occurs when the genetic material of the sperm combines with the genetic material of the ovum, forming a zygote, rather than when the sperm penetrates the ovum's membrane. Understanding the timing of events during conception and early pregnancy is crucial for maternity nurses to provide accurate information and support to expectant mothers. This knowledge helps in assessing and monitoring the progression of pregnancy, identifying any potential issues, and offering appropriate care and guidance to pregnant women.