Most common cause of abortion in first trimester is-
## **Core Concept**
The most common cause of abortion in the first trimester is related to chromosomal abnormalities. These abnormalities can lead to failed embryonic development or non-viable pregnancies. Understanding the genetic and molecular basis of early pregnancy loss is crucial.
## **Why the Correct Answer is Right**
Chromosomal abnormalities, particularly aneuploidy, are the leading cause of first-trimester abortions. Aneuploidy refers to the presence of an abnormal number of chromosomes in a cell, which is not a multiple of the haploid number. This condition disrupts normal development and often results in miscarriage. The most common chromosomal abnormalities leading to miscarriage include monosomy X (45,X), trisomy 16, and triploidy.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is not specified, but if we consider common causes of abortion, uterine anomalies or hormonal imbalances might be considered. However, they are less common causes compared to chromosomal abnormalities in the context of first-trimester abortions.
- **Option B:** Similarly, this option is unspecified but could potentially include infections or other maternal factors. While these can contribute to pregnancy loss, they are not the most common cause in the first trimester.
- **Option D:** This option is also unspecified but could potentially include other genetic or environmental factors. However, chromosomal abnormalities remain the most prevalent reason.
## **Clinical Pearl / High-Yield Fact**
A significant clinical pearl is that approximately 50-60% of first-trimester miscarriages are due to chromosomal abnormalities. This high prevalence underscores the importance of genetic counseling for recurrent pregnancy loss. A classic exam trap might involve confusing the causes of first-trimester versus second-trimester pregnancy loss, with the former being more commonly associated with chromosomal issues and the latter with cervical insufficiency or uterine anomalies.
## **Correct Answer:** . Chromosomal abnormalities.