Which statement is true regarding placentation in twin pregnancies?

Which statement is true regarding placentation in twin pregnancies?

• A. Monozygotic twins always result in dichorionic placentation
• B. Dizygotic twins always develop from one egg
• C. Monozygotic twins can develop from one egg and one sperm
• D. Dizygotic twins can develop from one egg only

Answer: (C)

In twin pregnancies, the characteristics of placentation can vary significantly based on whether the twins are monozygotic (identical) or dizygotic (fraternal). The statement that monozygotic twins can develop from one egg and one sperm is accurate because monozygotic twins originate from a single fertilized egg that divides into two embryos. This process can lead to different placental structures depending on when the division occurs, which is a critical aspect of understanding placentation in these twin types. For monozygotic twins, if division occurs early (within the first 3 days), each twin will have its own chorion and amnion, resulting in dichorionic-diamniotic placentation; if the division occurs later, the twins might share a chorion, and depending on the timing, they could be monochorionic-diamniotic or even monochorionic-monoamniotic. This contrasts with dizygotic twins (which arise from two separate eggs fertilized by two sperm), who will always have separate placentas and amniotic sacs, leading to dichorionic-diamniotic placentation in virtually all cases. Therefore, understanding that monozygotic twins originate from one egg

In twin pregnancies, the characteristics of placentation can vary significantly based on whether the twins are monozygotic (identical) or dizygotic (fraternal). The statement that monozygotic twins can develop from one egg and one sperm is accurate because monozygotic twins originate from a single fertilized egg that divides into two embryos. This process can lead to different placental structures depending on when the division occurs, which is a critical aspect of understanding placentation in these twin types.

For monozygotic twins, if division occurs early (within the first 3 days), each twin will have its own chorion and amnion, resulting in dichorionic-diamniotic placentation; if the division occurs later, the twins might share a chorion, and depending on the timing, they could be monochorionic-diamniotic or even monochorionic-monoamniotic.

This contrasts with dizygotic twins (which arise from two separate eggs fertilized by two sperm), who will always have separate placentas and amniotic sacs, leading to dichorionic-diamniotic placentation in virtually all cases.

Therefore, understanding that monozygotic twins originate from one egg