The Playbook

18 Weeks Pregnant: Getting Ready for the Anatomy Scan

By the Guide to Fatherhood editorial team. Last reviewed . 2 min read.

Checked against guidance from organizations like the AAP, CDC, ACOG and NHS (linked below). This is general information, not medical advice. Read our medical disclaimer.

Trimester2
Sizea bell pepper
Length / weightabout 5.6 in (14.2 cm), about 6.7 oz (190 g)

The baby's ears are in place and the baby may be starting to hear sounds. Nerves are being coated in myelin, which speeds up signals.

Your to-do list this week

  • Book the day off for the anatomy scan (usually between 18 and 22 weeks). This is the appointment to be at.
  • Decide together whether you want to know the baby's sex, and tell the sonographer at the start.
  • Read what the scan checks so you're not surprised by the long silences while they measure.
  • Start talking to the baby. Hearing is developing, and your voice is one it can learn.
A conversation to have this week

"Do we want to find out the sex, and who do we tell?" If one of you wants to know and the other doesn't, the sonographer can write it in a sealed envelope.

The baby this week

About the size of a bell pepper, the baby has ears in their final position and may be starting to hear sounds (NHS). Nerves are getting a protective coating called myelin, which helps signals travel faster (Mayo Clinic). If it’s a girl, the uterus and fallopian tubes are formed; if it’s a boy, the genitals may be visible on ultrasound.

How she may be feeling

The bump is obvious now. Backaches are common as her posture shifts, and some people get dizzy when standing up quickly because blood vessels are relaxed. Getting up slowly and staying hydrated helps.

Get ready for the anatomy scan

The anatomy (or “20-week”) scan usually happens between 18 and 22 weeks. According to ACOG, this detailed ultrasound checks the baby’s size and anatomy, the placenta’s position, and the amount of amniotic fluid.

What dads should know going in:

  • It’s long. Often 30 to 60 minutes. The sonographer may be quiet while measuring; that silence is normal, not a sign of bad news.
  • Sometimes the baby won’t cooperate. If a view isn’t clear, she may be asked to move, or you may need to come back. That’s common.
  • Results may come from her provider later, not the sonographer, who often can’t interpret findings in the room.
  • Some findings need follow-up, like a low-lying placenta, which often resolves by itself. Ask what happens next before you leave.

The sex question

If you want to know, tell the sonographer at the start. If you want a surprise, tell them that too, and avoid looking at the screen during certain views. If one of you wants to know and the other doesn’t, ask for a sealed envelope. And whatever you hear, the right first response is delight.

Then start talking to the bump. It feels silly for about a day.

Frequently asked questions

What does the anatomy scan check?

A detailed ultrasound, usually between 18 and 22 weeks, that checks the baby's growth and anatomy (brain, heart, spine, kidneys, limbs, and more), plus the placenta's location and the amount of amniotic fluid.

Can the baby hear us?

The structures of the ear are developing during the second trimester, and many babies begin responding to sound in the second half of pregnancy. Talking, reading and singing to the bump are good habits.

Sources

  1. Ultrasound Exams, American College of Obstetricians and Gynecologists
  2. Fetal development: The 2nd trimester, Mayo Clinic
  3. Week 18: Your baby and your body, NHS

We link to the original source for every medical and safety claim. Guidance changes; if a source has been updated since our last review, the source wins. How we research.