Pregnancy ultrasound scans explained

Ultrasound during pregnancy

For many people, pregnancy is the first time they see an ultrasound in action. These scans are a gentle and safe way to follow your baby's growth, check that everything is developing well, and answer important questions along the way. Seeing your baby on the screen can also be a moving and reassuring moment.

Ultrasound uses sound waves, not radiation, which is why it has been trusted in pregnancy care for decades. It is one of the most studied and safest tests in medicine.

The main scans you may be offered

The number and timing of scans can vary depending on your care and any specific needs. The most common scans follow a familiar pattern through the pregnancy.

The early or dating scan

Usually carried out in the first trimester, often between eight and fourteen weeks, the dating scan confirms the pregnancy, checks the baby's heartbeat and measures the baby to estimate the due date. It can also show whether you are expecting more than one baby. Early measurements are very accurate for working out how many weeks along you are.

The anomaly or detailed scan

Around the middle of pregnancy, often near twenty weeks, a detailed scan examines the baby's development closely. The sonographer checks the brain, the heart, the spine, the face, the kidneys, the stomach and the limbs, and looks at the position of the placenta. This scan offers reassurance and, if anything needs closer attention, allows time to plan care.

Growth and wellbeing scans

Later in pregnancy, some people are offered scans to check the baby's growth, the amount of fluid around the baby and the blood flow through the placenta and cord. These are more common if there is a particular reason to monitor closely.

What happens during the scan

Most pregnancy scans are done over the abdomen. You lie back, gel is applied to your belly, and the sonographer moves the probe to find the best views. In very early pregnancy, a small internal probe is sometimes used because it gives a clearer picture when the baby is still tiny. This is safe and your sonographer will explain it first.

A full bladder early on

For early abdominal scans you may be asked to drink water and keep a full bladder, which lifts the uterus into a better position. Later in pregnancy this is usually not needed.

You may be asked to wait or shift position if the baby is lying in a way that hides part of the view. Babies move a great deal, and sometimes a short break helps them turn.

Is ultrasound safe for my baby

This is one of the most common and understandable questions, and the answer is reassuring. Ultrasound has been used in pregnancy for many years and is considered very safe when carried out by trained professionals for medical reasons. It does not use radiation. Scans are kept to the time needed to gather the necessary information.

For this reason, health authorities advise against keepsake scans done purely for souvenir images outside of medical care, simply because there is no medical need to add extra exposure, however small.

Finding out the sex

Many parents wonder whether a scan will reveal the baby's sex. This is sometimes possible during the detailed scan, but it depends on the baby's position and on local practice. It is never the main purpose of the scan, which is always your baby's health and development.

After the scan

The sonographer may share some findings with you, but a full report goes to the doctor or midwife looking after you. If a scan raises a question, try not to panic, as many findings turn out to be minor or resolve on their own. Your care team will explain the next steps clearly.

If you have worries before, during or after a scan, talk to your midwife or doctor. They can explain what each scan is checking and offer the support and reassurance you need through your pregnancy.