Correct Answer: D

Rationale: After childbirth, a boggy uterus indicates poor uterine tone, which can lead to the formation of clots. Massaging the fundus helps the uterus contract and expel clots, reducing the risk of postpartum hemorrhage. Choices A, B, and C are incorrect because the main concern with a boggy uterus is the risk of clot formation and postpartum hemorrhage, not solely preventing intrauterine infection, massaging the lower uterine segment, or preventing the endometrial lining from sloughing.

Correct Answer: D

Rationale: According to the study, the chances of a woman bearing twins increase if she is a twin herself, if her mother was a twin, or if she has previously borne twins. Therefore, the correct answer is D. Choice A is incorrect because the study does not specify that she will bear only monozygotic twins. Choice B is incorrect as the study does not mention any decrease in the chances of becoming pregnant. Choice C is incorrect because the study does not provide information about the woman's health status, focusing instead on the likelihood of bearing twins.

Correct Answer: B

Rationale: Rh incompatibility occurs when an Rh-negative woman is carrying an Rh-positive fetus, not the other way around. Therefore, the statement that an Rh-positive woman is carrying an Rh-negative fetus is incorrect. Rh incompatibility can lead to hemolytic disease of the newborn, where maternal antibodies attack the fetal red blood cells. Choice A is incorrect because the statement is false. Choice C is incorrect as Rh incompatibility has a clear cause and effect relationship. Choice D is incorrect as Rh incompatibility can occur, but it depends on the Rh status of the mother and fetus.

Correct Answer: A

Rationale: A contraction duration of 100 seconds is too long and can indicate uterine hyperstimulation, which can lead to fetal distress and other complications. This prolonged contraction duration suggests that the uterus is not relaxing adequately between contractions, potentially compromising fetal oxygenation. Choice B, 'Four contractions in 10 minutes,' is a sign of tachysystole, which is concerning but not as immediately critical as the prolonged contraction duration. Choice C, 'Uterus is soft,' is not a reason to discontinue oxytocin; in fact, it is a normal finding. Choice D, 'Early deceleration of fetal heart rate,' while indicating fetal distress, is not a direct result of the oxytocin and may require intervention but not immediate discontinuation of the medication.

Correct Answer: B

Rationale: Folic acid deficiency during pregnancy is strongly associated with neural tube defects like spina bifida occulta. Adequate folic acid intake before and during early pregnancy significantly reduces the risk of such complications. Tobacco use (Choice A) is linked to other adverse outcomes but not specifically spina bifida occulta. Short intervals between pregnancies (Choice C) can increase the risk of preterm birth and low birth weight but are not directly linked to spina bifida occulta. Preeclampsia (Choice D) is a hypertensive disorder that poses risks to both the mother and baby but is not the primary factor contributing to spina bifida occulta development.