Correct Answer: D

Rationale: The correct answer is D: All of the above. Multiple gestations are at higher risk for complications such as premature labor, where contractions start before 37 weeks, leading to preterm birth. Twin-to-twin transfusion syndrome can occur in identical twins sharing a placenta, causing unequal blood flow. Preeclampsia, characterized by high blood pressure and organ damage, is more common in multiple pregnancies. Therefore, all choices A, B, and C are correct as they are common complications associated with multiple gestations.

Correct Answer: A

Rationale: The correct answer is A: Rhesus D incompatibility. Icterus gravis (severe jaundice) and hydrops fetalis (abnormal accumulation of fluid) are both conditions commonly associated with Rhesus D incompatibility between a mother and her fetus. This occurs when the mother is Rh-negative and the fetus is Rh-positive, leading to maternal antibodies attacking the fetal red blood cells, resulting in severe hemolytic anemia and subsequent complications. Explanation for why other choices are incorrect: B: ABO incompatibility typically leads to less severe jaundice and hemolytic disease compared to Rhesus D incompatibility. C: Physiological jaundice is a common and benign condition in newborns caused by the immaturity of the liver, not by blood type incompatibility. D: Instant perinatal death is not specifically associated with these conditions, but rather with other serious complications during childbirth.

Correct Answer: A

Rationale: The correct answer is A because secondary postpartum hemorrhage typically occurs between the 8th-14th day postpartum and can extend up to 6 weeks after delivery. This timeframe aligns with the physiological changes and healing process after childbirth. Choice B is incorrect because it contradicts the established timeframe for secondary postpartum hemorrhage. Choice C is incorrect as secondary postpartum hemorrhage is not rare but rather a recognized complication that can occur after childbirth. Choice D is incorrect as secondary postpartum hemorrhage does not happen sporadically, but rather follows a defined timeframe based on postpartum physiological changes.

Correct Answer: B

Rationale: The correct answer is B: Oligohydramnios. Oligohydramnios leads to reduced volume of amniotic fluid, which can result in poor fetal movements and inadequate cushioning for the fetus. This can increase the likelihood of abnormal fetal positions like shoulder presentation. Other choices are incorrect because: A: A sub-septate uterus is a structural uterine abnormality and not directly related to shoulder presentation. C: Prematurity may lead to preterm labor but is not specifically associated with shoulder presentation. D: Multiple pregnancy can increase the risk of malpresentation but is not a direct maternal cause of shoulder presentation.

Correct Answer: B

Rationale: The correct answer is B because pressure applied on the cervix by the presenting part in obstructed labor leads to edema of the vulva. This pressure causes obstruction of blood and lymphatic flow in the area, resulting in swelling and edema. Prolonged effort by the mother (choice A) would not directly cause vulvar edema. An ill-fitting presenting part (choice C) may contribute to obstruction but does not explain the mechanism of edema. Large presenting diameters (choice D) stretching the vulva would not directly cause edema without pressure on the cervix.