**Question:** Feilisation of two ova which have been discharged from the ovary at the same period by two seperate acts of coitus at sho intervals can be termed as

A. Multiple pregnancy
B. Dual pregnancy
C. Dichorionic diamniotic twin pregnancy
D. Monochorionic diamniotic twin pregnancy

**Correct Answer:** **D. Monochorionic diamniotic twin pregnancy**

**Core Concept:** Twin pregnancies can result from the fertilization of two ova by two separate acts of coitus, with each fertilized ovum developing into a separate embryo. These twin pregnancies can be classified based on the number of amniotic sacs and chorionic membranes.

**Why the Correct Answer is Right:** In the scenario described, both fertilized ova develop into separate embryos, leading to a situation where both fetuses share the same amniotic sac (diamniotic) and share a single layer of chorionic membrane (monochorionic). This type of twin pregnancy is called **Monochorionic diamniotic twin pregnancy**.

**Why Each Wrong Option is Incorrect:**

A. Multiple pregnancy (Multiple fetuses in a single uterine cavity): The question specifies that two fertilized ova develop into separate embryos, ruling out multiple pregnancy.
B. Dual pregnancy (Two fetuses in a single uterine cavity): Similar to multiple pregnancy, this option is incorrect as the scenario describes two separate embryos.
C. Dichorionic diamniotic twin pregnancy (Two fetuses in separate amniotic sacs and two layers of chorionic membranes): This option is incorrect because it describes twin pregnancies with separate amniotic sacs, which is not consistent with the provided scenario.

**Clinical Pearl:** Understanding the classification of twin pregnancies is crucial for obstetricians, as the management and monitoring of these pregnancies differ depending on their chorionic and amniotic membrane status. Monochorionic diamniotic twin pregnancies are particularly challenging and require close monitoring due to the increased risk of complications like twin-to-twin transfusion syndrome and placental abruption.