Which of the following is a common cause of early pregnancy loss before 20 weeks of gestation?

• A. Chromosomal abnormalities
• B. Bacterial vaginosis
• C. Ovarian cysts
• D. Cervical incompetence

Answer: (A)

Chromosomal abnormalities in the developing embryo are the most common reason a pregnancy ends before 20 weeks. Most miscarriages in the first trimester arise from fetal aneuploidy or other chromosomal defects that make the embryo nonviable, so implantation occurs but the pregnancy cannot continue. This explains why these losses are so frequent early on, and the risk rises with maternal age because meiotic errors become more common.

In contrast, bacterial vaginosis can be associated with adverse pregnancy outcomes, but it is not the typical driver of early spontaneous abortion. Ovarian cysts generally do not cause early pregnancy loss; they may relate to ovarian function or pain but aren’t a common cause of miscarriage itself. Cervical incompetence tends to cause losses later in pregnancy, often in the second trimester, due to painless cervical dilation, rather than in the early weeks of gestation.