The optimal period for Down syndrome screening

Down syndrome screening is an important prenatal screening procedure during pregnancy, primarily used to assess the risk of the fetus having Down syndrome, also known as trisomy 21. The optimal periods for Down syndrome screening are mainly divided into two stages:

1. First-trimester screening, performed between weeks 11 and 14 of pregnancy. During this stage, a combination of blood tests and nuchal translucency (NT) ultrasound examinations allows for earlier assessment of the risk of fetal Down syndrome. The accuracy rate of screening during this period is relatively high, reaching approximately 90%.

2. Second-trimester screening: If first-trimester screening is missed, screening can be conducted between weeks 16 and 18 of pregnancy. During this stage, maternal peripheral blood is drawn to analyze serum markers, and factors such as the mother's age, weight, and gestational age are also considered when assessing fetal risk. Although the accuracy rate of screening at this stage is somewhat lower, ranging from 60% to 70%, it is a more convenient procedure.

Both screening methods have their advantages: early screening offers higher accuracy while mid-trimester screening is more convenient. Pregnant women should choose an appropriate time for Down syndrome screening based on their individual circumstances and under the guidance of a physician, to help ensure the health of the fetus.