A man's wife is pregnant for the third time. One child was born with cystic fibrosis, and the other child is healthy. The man wonders what the chance is that this child will have cystic fibrosis. This type of testing is known as:

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Recurrence risk. Recurrence risk refers to the probability of a certain trait or condition occurring again in a family based on previous occurrences. In this case, since one child was born with cystic fibrosis, the man is concerned about the likelihood of the same condition affecting the third child. This type of risk assessment is crucial in genetic counseling to help individuals understand the chances of passing on certain genetic conditions to their offspring. Option A) Occurrence risk is incorrect because it typically refers to the probability of a certain condition occurring in any individual in the general population, not specifically within a family context. Option C) Predictive testing is not applicable in this situation as it usually involves testing an individual for a specific genetic mutation to predict their risk of developing a condition in the future, rather than assessing the likelihood of passing it on to offspring. Option D) Predisposition testing is also not the appropriate term here, as it generally involves identifying genetic markers that may increase an individual's likelihood of developing a particular condition, rather than assessing the risk of passing it on to their children. Understanding recurrence risk is essential for individuals with a family history of genetic conditions to make informed decisions about family planning and healthcare. It helps in providing accurate genetic counseling and guidance on potential risks associated with having children.

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.

Correct Answer: A

Rationale: The correct answer is A) Twinning and other multiple births are increasing because of the use of fertility drugs and delayed childbearing. This is the correct answer because advancements in fertility treatments have indeed led to an increase in multiple births. Fertility drugs and assisted reproductive technologies can stimulate the release of multiple eggs, increasing the chance of conceiving twins or more. Option B is incorrect because dizygotic twins (fraternal twins) arise from two separate eggs and cannot be conjoined. Conjoined twins result from the incomplete separation of a fertilized egg. Option C is incorrect because fraternal twins can be of the same or different genders. Fraternal twins occur when two separate eggs are fertilized by two different sperm. Option D is incorrect because the occurrence of identical twins is not influenced by race or ethnicity. Identical twins result from a single fertilized egg splitting into two embryos, which can happen in any ethnic group. Educationally, understanding the factors contributing to multiple births is crucial for maternity nurses to provide accurate information and support to expectant parents. This knowledge helps nurses address concerns, provide appropriate care, and offer guidance on managing the complexities that may arise with multiple pregnancies.