At which stage of pregnancy is the combined screening test typically performed?

The combined screening test is typically performed during the first trimester of pregnancy, specifically between 11 to 14 weeks gestation. This test is utilized to assess the risk of certain chromosomal conditions, such as Down syndrome, through a combination of maternal blood tests and an ultrasound examination. The ultrasound measures the nuchal translucency, which is the fluid at the back of the baby's neck. Early detection and risk assessment during this crucial period allow for informed decision-making regarding further testing or interventions, if needed. This timing is advantageous because it coincides with the most effective window for evaluating these risks and considering options for the management of the pregnancy.

In contrast, tests conducted in the second or third trimester, or at the time of delivery, pertain to different assessments and are not aimed specifically at early genetic screening. Therefore, the combined screening test's early scheduling plays a vital role in prenatal care.