A pregnant woman at 25 weeks' 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?

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) 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.

Correct Answer: A

Rationale: The correct answer is A) Contact between maternal blood and fetal capillaries within the chorionic villi. The placenta acts as a barrier between the maternal and fetal circulations while allowing for the exchange of oxygen, nutrients, and waste products. Within the chorionic villi, small finger-like projections of the placenta, maternal blood comes into close contact with fetal capillaries, facilitating the transfer of these essential substances. Option B) Interaction of maternal and fetal pH levels within the endometrial vessels is incorrect because pH levels do not directly facilitate the exchange of substances between the mother and fetus. Option C) A mixture of maternal and fetal blood within the intervillous spaces is incorrect as maternal and fetal blood do not mix in the placenta due to the presence of the placental barrier. Option D) Passive diffusion of maternal carbon dioxide and oxygen into the fetal capillaries is incorrect because while passive diffusion does occur, it is the contact between maternal blood and fetal capillaries within the chorionic villi that allows for this exchange to take place efficiently. Understanding the intricacies of placental function is crucial in comprehending the physiological processes that support fetal development. By grasping how the placenta facilitates the exchange of substances between the mother and fetus, healthcare professionals can better address issues that may arise during pregnancy and ensure optimal maternal and fetal health.