This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy of the female genital tract, Subject name: Gynaecology & Obstetrics
[{'content': 'A 28-year-old G1P0 woman is diagnosed as having a twin gestation at 15 weeks gestation. Careful examination of the membranes reveals that there is a very thin membrane between the two fetuses. Which of the following statement is most accurate \nSelect and explain. \nA. It is likely that this is a monozygotic gestation., B. It is likely that this is a dizygotic gestation., C. It is likely that there are two separate placentas., D. It is likely that one fetus is a male and the other a female.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The ultrasound findings are consistent with monochorionic, diamniotic twins, since there is only a thin membrane between the two gestations. Since a dizygotic gestation always gives rise to a dichorionic diamniotic gestation, this patient must have a monozygotic pregnancy which split at 4 to 8 days after feilization. A monozygotic pregnancy is at greater risk for IUGR, stillbih.', 'role': 'assistant'}]