Which marker is included in a first-trimester screen for genetic disorders?

In the context of a first-trimester screen for genetic disorders, human chorionic gonadotropin (hCG) plays a critical role as one of the biochemical markers assessed. This hormone is produced by the placenta shortly after implantation, and its levels can indicate certain conditions or risks in the developing pregnancy.

The first-trimester screen typically evaluates the levels of hCG along with other markers to assess the risk for chromosomal abnormalities such as Down syndrome (trisomy 21) and trisomy 18. Elevated levels of hCG are often associated with an increased risk of these conditions.

In contrast, estriol is not typically included in the first-trimester screening and is instead measured in the second trimester. Folic acid is a crucial vitamin for prenatal health, but it does not serve as a marker for genetic screening. Similarly, while alpha-fetoprotein (AFP) is significant in second-trimester screenings, it is not part of the first-trimester assessment.

By utilizing hCG as a marker in the first-trimester screen, healthcare providers can gather important information regarding the potential genetic risks, allowing for early intervention or further testing if necessary.