1st Trimester Test

Overview

Prenatal screening tests are available to identify pregnancies at increased risk

of chromosomal anomalies such as trisomy 21, trisomy 18 and some structural

anomalies such as neural tube defects. Ultrasound and maternal serum

screening tests identify fetuses with an increased likelihood of having one of

these conditions. Sometimes these conditions are associated with long-term

and serious morbidity, and some require neonatal investigation or treatment.

Screening tests like first trimester screening lead to an offer of a diagnostic test

(ultrasound, chorionic villus sampling or amniocentesis) to women with

pregnancies identified at increased risk of fetal anomaly. In the event of the

diagnose of an anomaly, the parents have enough time to be mentally prepared

choose to terminate or continue with the pregnancy.

What is First Trimester Screening?

This is a prenatal test that combines a maternal blood screening test with an

ultrasound evaluation of the fetus and maternal age-related risk to identify risk

for specific chromosomal abnormalities, including Down Syndrome and

Edwards syndrome. By using this approach, various investigators have

reported detection rates for Down Syndrome of 85 to 90 percent at a 5 percent

false-positive rate. 1,2

Who should consider First Trimester Screening?

It is recommended for pregnant women of any age who would like to know their

early information about the health of a pregnancy without invasive testing.

Serious chromosomal abnormalities are more commonly associate with

pregnancies in women age 35 and older, but they can occur at any age.

When should First Trimester Screening to be tested?

Typically, it can be done between the 11th week and 14th week of pregnancy.