What are the characteristics of a dizygotic pregnancy?

In a dizygotic pregnancy, which occurs when two separate eggs are fertilized by two different sperm cells, the characteristic feature is the presence of two distinct placentas and two separate amniotic sacs. Each embryo develops independently, leading to this configuration.

Dizygotic twins, also known as fraternal twins, can vary significantly in their genetic makeup, just like any siblings born at different times. The existence of two placentas and two amniotic sacs provides each twin with its own space and circulatory system, which minimizes potential complications that could arise from sharing a placenta or sac.

The other options describe configurations that do not apply to dizygotic pregnancies. For instance, one placenta and one amniotic sac typically characterize monochorionic, monoamniotic twins, which occur in a different type of twin pregnancy where a single fertilized egg divides. Similarly, one placenta with two amniotic sacs refers to a different setup encountered in dizygotic twins who share a placenta but are otherwise genetically distinct. Having three placentas and three amniotic sacs would suggest a scenario of three separate fertilized eggs, which does not pertain to the question on dizygotic pregnancies specifically.