What the blood test actually looks for
Cell-free DNA screening covers a handful of chromosome problems. It is not a scan of the whole baby.
The blood test taken from your arm in early pregnancy is usually called cell-free DNA screening, or NIPT. It looks at fragments of DNA from the placenta that are circulating in your blood.
Current guidance comes from a 2025 society document that ACOG endorsed in November 2025, together with an ACOG Practice Advisory of January 2026. Together these replaced ACOG's earlier Practice Bulletin 226, which is no longer current guidance. If you are handed an information sheet citing Practice Bulletin 226, it is out of date.
What the guidance recommends, in its own words:
We recommend that cfDNA screening for common aneuploidies (trisomies 21, 18, and 13) be made routinely available to all obstetrical patients (GRADE 1B).
We recommend that screening for sex chromosome aneuploidies be made available to obstetrical patients as an 'opt-in' consideration with appropriate pretest counseling (GRADE 1C).
We do not recommend routine general population screening for any microdeletion condition.
We do not recommend the routine use of cfDNA testing for large genome-wide copy number deletions or duplications (GRADE 1C).
Conventional combined serum or first-trimester ultrasound screening or both can lead to a range of findings that cfDNA may not detect, including fetal structural abnormalities, unanticipated genetic diagnoses, or risk for adverse perinatal outcomes.And:
An anatomic survey is recommended for all patients to detect structural abnormalities regardless of aneuploidy screening method.
In plain language: the blood test does not look at your baby's body. It counts chromosomes. A heart, a spine, a kidney, a limb, a face: none of those is what this test is for.
Commercial panels differ from laboratory to laboratory, so nobody can tell you from a distance what your particular panel does and does not include. Ask for the list.
A negative result means that your fetus is at lower risk of having the disorder compared with the general population. It does not rule out the possibility that your fetus has the disorder.
That is the most honest sentence any professional body has written about this test, and it is on a public web page. It is also the sentence least often said out loud in a clinic.
"Am I opting in to anything beyond trisomy 21, 18 and 13?"
"Is any part of this panel one that ACOG does not recommend routinely?"