Spontaneous aboion in 1st trimester is caused by:
**Core Concept**
In the first trimester, spontaneous abortion, also known as miscarriage, is a common complication of early pregnancy. It occurs due to various factors that disrupt the delicate balance of the endometrial environment, leading to embryonic or fetal demise.
**Why the Correct Answer is Right**
The correct answer is related to the role of progesterone in maintaining pregnancy. Progesterone is essential for the implantation and maintenance of the embryo in the endometrium. A deficiency in progesterone can lead to decidual necrosis, endometrial shedding, and ultimately, spontaneous abortion. This is often due to a luteal phase defect, where the corpus luteum fails to produce sufficient progesterone.
**Why Each Wrong Option is Incorrect**
* **Option A:** While genetic abnormalities can contribute to miscarriage, they are not the primary cause in the first trimester.
* **Option B:** Hormonal imbalance, particularly an excess of human chorionic gonadotropin (hCG), can contribute to complications in early pregnancy, but it is not the primary cause of spontaneous abortion.
* **Option C:** Infections and autoimmune disorders can cause miscarriage, but they are less common causes in the first trimester.
**Clinical Pearl / High-Yield Fact**
A patient with a history of recurrent first-trimester miscarriages should be evaluated for luteal phase defect, which can be diagnosed with a progesterone level check on the 21st day of a 28-day menstrual cycle.
**Correct Answer:** D. Progesterone deficiency.