Down Syndrome Screening
What is Down Syndrome? Down Syndrome is caused by the abnormality of the 21st chromosomes, which has one additional chromosome. Children with Down syndrome will have low IQ (25-50) and particular facial features such as small round head, larger tongue, pointy eyes, flattened nose, as well as other physical symptoms such as myasthenia gravis, congenital heart disease, etc.
Why do we need screening? Down syndrome is found in 1 out of 800 to 1,000 babies. There is a misunderstanding that babies with Down syndrome can occur when the mother is older than 35 years old. In fact, however, the symptom is more frequently found in a child with a younger mother.Statistically, in 100 children with Down syndrome, about 25-30 came from motherswho wereyounger than 35 years and 70-75 came from younger mothers.
Screening of Down Syndrome VS. Diagnosis of Down Syndrome
Screening of Down syndrome is done by measuring chemical substances in the mother’s blood, alongside ultrasound test and calculation of the result to define the risk of Down syndrome. The screening does not increase the risk of miscarriage and is less expensive than diagnosis. The screening is not a diagnosis and can only tell whether the baby has a “higher” or “lower” risk of having Down syndrome
Diagnosis of Down syndrome is done by examination of a baby’s chromosomes to determine whether the baby “has” or “does not have” Down syndrome. This method of examination is precise but can increase the risk of miscarriage as it requires biopsy, amniocentesis or blood test. The method is also expensive.
How is the screening performed? During the first three months of pregnancy (11-13 weeks ofpregnancy), the method is done by blood sampling of mother to examine PAPP-A + hCG level, combined with information of the baby’s neck size obtained via ultrasound. The screening can detect 87% of the cases of Down syndrome.
During three to six months of pregnancy (15-20 weeks of pregnancy), the method is done by blood sampling of mother to check MSAFP + hCG + uE3 + inh A level. The screening can detect 81% of the cases of Down syndrome.
Result Reading The results will come out in aratio such as 1 : 2,000 which informs “higher” or “lower” risk of Downsyndrome in the baby. In case there is a high risk of Down syndrome, the doctor will recommend mother to have further examinations to confirm whether the baby will have Down syndrome. In the case of lower risk, the doctor will not recommend any further examinations.
From this information, pregnant mothers who can still receive screening are recommended to ask their gynecologist about the screening,in order to reassure that their child will not have “Down Syndrome”.