Katie wonders when she will first be able to hear her fetus's heartbeat through a stethoscope. You tell her that this should happen by the __________.

Correct Answer: B

Rationale: The correct answer is the third month of pregnancy (choice B). During the third month of pregnancy, which is around 9-12 weeks, a fetal heartbeat can typically be heard using a stethoscope. This is an exciting milestone for expectant parents as it provides reassurance about the baby's well-being. Choices A, C, and D are incorrect because by the fourth week of pregnancy, the fetal heartbeat is not usually detectable with a stethoscope. The end of the second trimester and the beginning of the third trimester are too late in the pregnancy timeline for this milestone.

Correct Answer: D

Rationale: The harm done by teratogens depends on the age at the time of exposure. This means that the effects may vary depending on the developmental stage of the fetus when exposed to the teratogen. Teratogens can have different impacts at different stages of pregnancy, leading to a range of potential outcomes in terms of physical and/or cognitive development. Choices A, B, and C are incorrect because the harm caused by teratogens is not straightforward, may not be apparent at birth, and can go beyond physical damage, affecting cognitive development as well.

Correct Answer: B

Rationale: Mateo, being born prematurely to a cocaine-addicted mother, is at risk for several health issues. One common effect of prenatal drug exposure is a higher likelihood of sensory and regulatory problems, such as having abnormally shrill and piercing cries. This is a potential outcome that Mateo's caregivers can expect due to his circumstances. Choice A is incorrect as there is no direct correlation between being born prematurely to a cocaine-addicted mother and being very attentive to the environment. Choice C is incorrect as overcoming harmful effects of drug exposure by age 3 is overly optimistic and may not be the case for all children exposed to drugs prenatally. Choice D is incorrect as rapid motor development is not typically associated with prenatal drug exposure.

Correct Answer: B

Rationale: Passive smoking, also known as secondhand smoke, can have harmful effects on pregnancies. Research has shown that exposure to smoke-filled environments during pregnancy is linked to low birth weight, infant death, and childhood respiratory illnesses. Pregnant women should avoid exposure to secondhand smoke to protect the health of their unborn babies. Choice A is incorrect because passive smoking affects both the mother and the unborn child, not just children born to heavy smokers. Choice C is incorrect as it underestimates the risks of smoke-filled environments on unborn children. Choice D is incorrect as research has already established the harmful effects of passive smoking on pregnancies.

Correct Answer: B

Rationale: Low-level radiation, whether from industrial leakage or medical X-rays, can increase the risk of childhood cancer by potentially damaging the developing fetus's cells. Even though the risk is relatively low, it is still a significant concern that should be acknowledged and monitored closely, especially during prenatal development. Choice A is incorrect as low-level radiation can still be harmful on its own without the need to be combined with other teratogens. Choice C is incorrect because low-level radiation exposure can indeed cause lasting damage, especially in the context of childhood cancer risk. Choice D is incorrect because low-level radiation exposure, even during the last trimester, can pose risks to the developing fetus and is not considered entirely safe.