Correct Answer: B

Rationale: Betamethasone is a corticosteroid given to stimulate fetal lung maturity and reduce the risk of respiratory distress syndrome in preterm infants. Ampicillin (Choice A) is an antibiotic and does not prevent respiratory distress syndrome. Terbutaline (Choice C) is a tocolytic used to inhibit contractions and does not directly prevent respiratory distress syndrome. Butorphanol tartrate (Choice D) is an opioid analgesic and does not have a role in preventing respiratory distress syndrome in preterm infants.

Correct Answer: A

Rationale: The correct answer is A. Positioning the car seat at a 45-degree angle is crucial to prevent the baby's head from falling forward, which can obstruct the airway. Choice B is incorrect because the recommendation is to keep the car seat rear-facing until the baby reaches the height or weight limit set by the car seat manufacturer, typically beyond 12 months. Choice C is incorrect as the harness should be snugly placed at or below the baby's shoulders, not above. Choice D is incorrect as the retainer clip should be positioned at armpit level to secure the harness straps properly.

Correct Answer: C

Rationale: Progestin is the synthetic hormone used to prevent miscarriages. While it is beneficial in maintaining pregnancy, in some cases, it can lead to masculinization of the fetus. Testosterone (Choice A) and estrogen (Choice B) are not typically used to prevent miscarriages and do not cause masculinization of the fetus in this context. Oxytocin (Choice D) is a hormone involved in labor and breastfeeding, but it is not used to prevent miscarriages nor does it cause masculinization of the fetus.

Correct Answer: A

Rationale: At 14 weeks of gestation, the uterus is still relatively low in the abdomen. Placing the Doppler midline 2 to 3 cm above the symphysis pubis is appropriate for assessing the fetal heart rate. This location allows for better detection of the fetal heart tones as the uterus is at a lower position during this stage of pregnancy. Placing the Doppler on the left upper abdomen would not be ideal at 14 weeks gestation as the uterus is not yet at that level. Placing it two fingerbreadths above the umbilicus or lateral at the xiphoid process would also not be accurate for locating the fetal heart rate at this stage of gestation.

Correct Answer: D

Rationale: The correct answer is D: Absent patellar reflexes. Absent patellar reflexes can indicate magnesium toxicity, a serious condition that requires immediate intervention to prevent respiratory depression or cardiac arrest. Dizziness while standing (choice A) is common in pregnancy but does not specifically indicate magnesium toxicity. Sinus tachycardia (choice B) can be a normal response to magnesium sulfate but does not indicate toxicity. Lower back pain (choice C) is common in pregnancy and not specifically associated with magnesium toxicity.