Pregnancy

Pregnancy Ultrasound Schedule: What Each Scan Can Show

Ultrasound uses sound waves to create images of your baby, placenta and pregnancy. The exact pregnancy ultrasound schedule depends on where you receive care, your medical history and how the pregnancy is progressing. In England, routine care usually includes scans at 11 to 14 weeks and 18 to 21 weeks; ACOG says at least one standard scan is generally performed, usually at 18 to 22 weeks. Extra scans are not automatically a sign that something is wrong.

Pregnant patient viewing an ultrasound image with a healthcare professional

Written by HelloMommy editorial teamUpdated August 28, 20263 min read

Early and dating scans

A first-trimester scan may confirm that the pregnancy is in the uterus, estimate gestational age, count babies and check cardiac activity. In England, the dating scan is offered at 11 to 14 weeks and may include nuchal translucency measurement if you choose combined screening. An earlier scan may be recommended for pain, bleeding, uncertain dates, fertility treatment or another clinical reason. Ultrasound this early cannot assess all organs in detail.

The mid-pregnancy anatomy scan

The detailed scan is commonly performed around 18 to 22 weeks; the NHS window is usually 18 to 21 weeks. It examines major body structures, growth, the placenta and amniotic fluid. It can identify many physical conditions, but no scan can find every condition or guarantee that a baby has no health problem. Sometimes the baby's position makes a clear view difficult and a repeat appointment is offered.

Growth and third-trimester scans

Routine third-trimester ultrasound is not offered to everyone. Your care team may recommend one or a series of scans to monitor growth, fluid, placental location, blood flow or baby position. Reasons can include a measurement concern, twins, high blood pressure, diabetes, a low-lying placenta or a previous pregnancy complication. The timing and frequency should answer a specific clinical question.

What happens at an ultrasound

For an abdominal scan, gel is placed on your abdomen and a sonographer moves a transducer over the skin. Some early scans use a transvaginal transducer to obtain clearer images. Follow the clinic's instructions about whether to arrive with a full bladder. Medical ultrasound has no known harmful effects in pregnancy, but professional bodies advise using it for medical purposes and having it performed by qualified staff.

Understanding results and follow-up

The sonographer may explain findings during or after the appointment. A result that needs another look is not a diagnosis: you may be offered a repeat scan, specialist ultrasound or diagnostic testing. Screening is optional, and your clinician should explain what a test can and cannot tell you before you decide. Ask when results will arrive, what happens next and who to contact with questions.

Frequently asked questions

How many ultrasounds do you need during pregnancy?

There is no universal number. England routinely offers two, while ACOG describes at least one standard scan, usually at 18 to 22 weeks. Your country, health and pregnancy findings determine your schedule.

Can an ultrasound detect every condition?

No. Ultrasound can screen for many structural conditions and assess growth, but it cannot detect every condition and some views may be limited by gestation or baby position.

Are extra scans safe?

Diagnostic ultrasound has no known harmful effects when used appropriately. It should be performed for a medical reason by qualified professionals, with the lowest exposure needed to obtain useful information.

Sources

This article is for general information only and is not medical advice. Always talk to your doctor or midwife about your own pregnancy.