Three screenings, each with its own purpose. When to go and why “we will catch up later” does not work.
During pregnancy a woman has at least three ultrasound screenings. Each one has its own purpose — and “skip it now, catch up later” does not work here: some parameters can only be assessed within a narrow window of weeks.
First screening: weeks 11–14
The most important scan of the pregnancy. The doctor confirms the due date, measures nuchal translucency and the nasal bone — markers of chromosomal abnormalities — and rules out major malformations. Combined with a blood test this gives an individual risk calculation.
Doctor’s tip: come to the first screening with your blood test results (PAPP-A and β-hCG) — then the risk is calculated right away, without a second visit.
Second screening: weeks 18–21
This is the “anatomy” scan: the doctor examines every organ of the fetus in turn — brain, heart, kidneys, spine, limbs. The placenta, the amount of amniotic fluid and the length of the cervix are assessed. At this stage the baby’s sex is usually clearly visible.
Third screening: weeks 30–34
The goal is preparing for birth: the position of the fetus, estimated weight, the state of the placenta and blood flow. If needed, Doppler is added — a study of the umbilical cord and uterine vessels.
“Ultrasound does not replace care by a gynaecologist — it answers the doctor’s specific questions. The ideal scheme: screenings on schedule plus planned check-ups.”
Is an “extra” ultrasound harmful?
Ultrasound is not an X-ray: there is no ionising radiation, and studies have not confirmed any harm to the fetus. But there is also no point in scanning “for a photo” every two weeks — a scan should answer a medical question.
- Bleeding or pain — an unscheduled, urgent scan
- The baby moves less after week 28 — a reason for CTG and ultrasound
- Doubts about the due date — a clarifying scan before week 11, as prescribed
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