Pregnancy is a miraculous journey where mothers nurture new life. Yet we face many uncertainties: Could maternal factors affect the baby's growth? Is the baby developing normally in all aspects? This article introduces knowledge about fetal anomaly screening during pregnancy, hoping to assist expectant mothers.
Screening Tests
During early pregnancy, your doctor may recommend screening tests for Down syndrome caused by chromosomal abnormalities and spina bifida resulting from brain or spinal cord defects. These include various tests such as blood tests, specialized ultrasound scans, or a combination of both.Test results indicate the likelihood of carrying a fetus with abnormalities. If results show a high risk, further diagnostic tests are needed to confirm whether the fetus is affected. If results indicate a low risk, additional testing may not be necessary, though this does not guarantee a healthy fetus. Diagnostic tests only predict the probability of abnormalities.
Blood Tests
Maternal Serum Alpha-Fetoprotein (AFP) Test: This blood test screens for fetal conditions such as anencephaly (absence of the brain), skull defects, and spina bifida. Ideally performed around the 16th week of pregnancy, it may require a blood draw. If your pregnancy duration is uncertain, a dating ultrasound is recommended to determine the optimal testing window.
Maternal Serum Screening Test: A blood test performed between 14 and 21 weeks of pregnancy can screen for Down syndrome. This test is typically conducted on the same blood sample used for AFP testing, usually around week 16. The probability of Down syndrome is calculated based on the mother's age, AFP levels, and other blood components.
Ultrasound Screening
Nuchal translucency (NT) scanning is a specialized ultrasound performed between 11 and 13 weeks. It measures fluid thickness at the back of the baby's neck. A computer then calculates the risk of Down syndrome based on the baby's size, gestational age, and NT measurement.
Results
After testing, your doctor will inform you when results will be available. If the initial screening is normal, your doctor may recommend further testing such as high-resolution ultrasound, chorionic villus sampling (CVS, typically between 11 and 14 weeks), or amniocentesis (available from 16 weeks onward).Not everyone needs these tests, as they depend on the baby's risk level. You may choose to let the baby develop naturally.
If you have any questions about the results, consult your doctor immediately.