Compared with singleton pregnancies, multifetal gestations have a higher risk of all EXCEPT which of the following complications?
Compared with singleton pregnancies, multifetal gestations have an infant mortality rate that is how many times greater?
Which of the following mechanisms may prevent monozygotic twins from being truly “identical”?
b. Unequal division of the protoplasmic material
c. Variable expression of the same genetic disease
A patient delivers a twin gestation in which one infant has blood type A and one has type O. The patient and her husband are both type O. A particular phenomenon is proposed as the etiology of the discordant blood types. How would you explain this to the mother?
a. The proposed phenomenon does not spontaneously occur in humans.
b. It involves fertilization of one ovum that splits into two during the same menstrual cycle.
c. It involves fertilization of two ova within the same menstrual cycle, but not at the same coitus.
d. It involves fertilization of two ova separated in time by an interval as long as or longer than a menstrual cycle.
When trying to establish chorionicity of the pregnancy shown in the image here, which of the following statements is true?
Reproduced with permission from Cunningham FG, Leveno KJ, Bloom SL, et al (eds): Multifetal pregnancy. In Williams Obstetrics, 24th ed. New York, McGraw-Hill, 2014, Figure 45-7B.
a. There are two placentas.
b. The twins must be monozygotic.
c. The twins share the same amnion.