Normal range for second-trimester Down syndrome screening results

Mid-trimester screening, also known as mid-pregnancy screening, refers to the initial assessment of the likelihood that a fetus may have congenital or hereditary disorders during the second trimester of pregnancy. So what is the normal range for mid-trimester Down syndrome screening results?

Normal Range for Mid-Trimester Down Syndrome Screening Results

The normal value for mid-trimester Down syndrome screening in pregnant women should be 1:308. Minor deviations in the data are common, and pregnant women are advised not to worry excessively. Down syndrome screening is primarily conducted between weeks 16 and 20 of pregnancy to assess the risk of fetal trisomy 21, trisomy 18, and open neural tube defects. Prior to undergoing Down syndrome screening, a recent ultrasound report should be available to confirm gestational age. If appropriate, blood samples can be collected in the morning after an overnight fast.

Pregnant women over the age of 35 or those carrying twins are generally not recommended for standard Down syndrome screening. Advanced maternal age pregnancies may proceed directly to amniocentesis. If the Down syndrome screening indicates high or borderline risk, it is recommended to consult a genetic counseling clinic at a higher-level hospital, and amniocentesis may be necessary when indicated.

The purpose of Down syndrome screening is to evaluate the risk level of fetal Down syndrome. The test is performed between 15 and 20+6 weeks of gestation by drawing venous blood from the pregnant woman to measure levels of human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and alpha-fetoprotein (AFP), which are then used to calculate the risk of fetal Down syndrome. Children with Down syndrome typically have intellectual disabilities, distinctive facial features, frequent multi-organ malformations, and reduced ability to live independently, with no effective cure currently available in clinical practice. We hope this information has been helpful. Wishing you good health and happiness!