The most common cause of early abortion is:

RUHS, Jaipur, PB B.Sc Nursing Entrance-2020

Obstetrics & Gynaecology

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2020

Explanation

Chromosomal abnormalities are the most frequent cause of early pregnancy loss (miscarriage), responsible for approximately 50% of all cases in the first trimester.
These are typically random, non-hereditary genetic errors that occur during the formation of the egg or sperm or at the time of fertilization, making the resulting embryo non-viable.
The most common types of chromosomal abnormalities found in miscarriages are autosomal trisomies (e.g., Trisomy 16), Monosomy X (Turner syndrome), and triploidy (an extra set of chromosomes).

Option A: While certain maternal infections (e.g., TORCH - Toxoplasmosis, Other, Rubella, Cytomegalovirus, Herpes) can lead to pregnancy loss, they are an uncommon cause of early miscarriages, accounting for less than 5% of cases.
Option B: Endocrine disorders, such as poorly controlled diabetes mellitus, thyroid disease, or a luteal phase defect, can cause miscarriage. However, they are responsible for only about 10-15% of early losses, making them less common than genetic causes.
Option D: Advanced parental age, particularly maternal age over 35, is a major risk factor, but it is not the direct cause. It significantly increases the probability of chromosomal abnormalities occurring in the egg, which is the actual cause of the miscarriage.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of Early Spontaneous Abortion as background academic context rather than a clinical decision trigger.
It is crucial for nurses to counsel patients that the majority of early miscarriages are due to random, non-preventable genetic events. This understanding can help alleviate the profound feelings of guilt, failure, and self-blame that many women and couples experience after a pregnancy loss.
Patient education should focus on the fact that a single miscarriage does not typically indicate an underlying problem with fertility or the ability to have a healthy future pregnancy.
What if? If a patient experiences recurrent pregnancy loss (defined as two or three consecutive miscarriages), the clinical approach changes. Investigation for underlying causes, such as parental chromosomal analysis (karyotyping), screening for antiphospholipid syndrome, and assessment of uterine anatomy, becomes necessary, as the likelihood of a persistent, non-random cause increases.

How to Approach the Question

First, identify the keywords in the question: 'most common cause' and 'early abortion' (which typically refers to the first trimester).
Recall the main categories of causes for miscarriage: fetal (genetic), maternal (anatomic, endocrine, infectious, immunologic), and environmental/paternal.
Compare the relative frequencies of these causes. Remember that fetal genetic issues are overwhelmingly the most frequent reason for early pregnancy failure.
Analyze the options. Differentiate between a direct cause and a risk factor. 'Advanced parental age' is a risk factor that leads to an increased incidence of the direct cause, 'chromosomal abnormality'.
Select the option that represents the most frequent direct cause of the event, which is 'Chromosomal abnormality'.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 89-95

E6 Gynecology Williams p. 142-173