What is the typical percentage of spontaneous abortions that occur in the first 12 weeks of pregnancy?

The correct percentage of spontaneous abortions that typically occur in the first 12 weeks of pregnancy is 80%. This high percentage can be attributed to several factors. Early pregnancy losses are often linked to chromosomal abnormalities, which account for a significant portion of first-trimester miscarriages. Additionally, the risk of miscarriage decreases as the pregnancy progresses past this initial stage, where many embryos that are not viable are lost.

It's important to understand that while estimates can vary depending on the population studied and specific circumstances, the consensus in obstetric and reproductive health literature generally identifies that a substantial number of spontaneous abortions occur within the first trimester. The first 12 weeks of gestation is a critical period for embryonic development, and factors such as hormonal support, uterine environment, and maternal health all play essential roles in the viability of the pregnancy during this time.

In contrast, percentages lower than this do not accurately reflect the broader evidence in medical literature regarding the incidence of early pregnancy loss.