**Question:** Cause of repeated 2nd trimester foetal loss:

A. Thalassaemia
B. Rh incompatibility
C. Maternal diabetes mellitus
D. Immune thrombocytopenic purpura (ITP)

**Core Concept:** Repeated fetal loss, particularly in the 2nd trimester, can be attributed to various underlying causes, including genetic disorders, maternal medical conditions, and maternal immune factors.

**Why the Correct Answer is Right:**

The correct answer is Maternal Diabetes Mellitus (Option C). Repeated second trimester fetal losses can be due to maternal medical conditions. Diabetes Mellitus, if poorly controlled or poorly diagnosed, can lead to increased fetal loss. The high blood sugar levels in diabetic mothers can cross the placenta and harm the developing fetus, leading to preterm labor, low birth weight, and increased risk of congenital anomalies.

**Why Each Wrong Option is Incorrect:**

A. Thalassaemia (Option A) is a genetic disorder affecting the red blood cells, typically inherited as a co-dominant trait. It is unlikely to be the primary cause of repeated second trimester fetal loss without other complicating factors.

B. Rh incompatibility (Option B) is a blood group incompatibility issue that may lead to hemolytic disease of the fetus and newborn, but is usually associated with late-stage pregnancy complications rather than second trimester losses.

D. Immune thrombocytopenic purpura (Option D) is a maternal autoimmune disorder where the mother's immune system attacks her own platelets, leading to thrombocytopenia. This condition is more commonly associated with late-stage pregnancy or neonatal complications rather than second trimester fetal losses.

**Clinical Pearl:**

Understanding the potential causes of repeated second trimester fetal loss is essential for accurate diagnosis and appropriate management. In addition to addressing the specific causes mentioned in the options, it is crucial to investigate and manage other potential causes, such as chromosomal abnormalities, infections, or maternal medical conditions like hypertension, thyroid disorders, or other autoimmune disorders. Consulting a geneticist or obstetrician is often necessary in cases of unexplained recurrent miscarriages. Early identification and management of underlying causes can significantly improve pregnancy outcomes.