20th week: Halfway there

Weeks and days
19+0 to 19+6
Month
5
Trimester
2

By the end of the 20th week of pregnancy, half of the 40 weeks is behind you. This week, the fetus grows from about 153 to 166 millimeters and weighs around 330 grams by the end. In Germany, this week falls right in the middle of the time window for the second ultrasound paid for by health insurance.

A single large sweet potato lies in an open palm on beige linen
Sweet potato180 to 220 mm, the size of your baby at the end of the week

Week 20 of 40

Calculate your week
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How big is the fetus?

050100150200250 mm18th week130 to 14219th week142 to 15320th week153 to 16621st week166 to 179Sweet potato at the same scale

153 to 166 mm

By the end of the week, the fetus is about the size of a sweet potato. From head to heel, it measures about 25 centimeters, and its skin is now covered with vernix.

Crown-rump length at the transition from the UNSW Embryology table to the values from Archie et al. 2006, weight according to the WHO growth charts. A large sweet potato is 180 to 220 mm long.

This week

Your baby

  • Hearing develops from low to high: the baby perceives low-pitched sounds first and high-pitched ones only weeks later.
  • There are rest periods between movements. In one study, they lasted 4 minutes on average at 20 weeks.
  • In girls, the uterus is now formed.

Your body

  • The distance from the pubic bone to the top of the uterus is on average 20 cm by the end of the week. From now on, this distance in centimeters roughly matches the number of completed weeks.
  • Your belly sometimes becomes hard for 30 to 60 seconds. Many notice these practice contractions (Braxton Hicks contractions) from about now; they are usually painless.
  • If the placenta is at the front, first-time mothers in one study felt the first movements on average only at 19+0. It often takes until the 22nd or 23rd week.

What matters now

  • In Germany, the second basic ultrasound is scheduled between 18+0 and 21+6, and you are right in the middle of the time window.
  • If the pregnancy ends in a miscarriage from now on, in Germany you are entitled to 8 weeks of maternity protection, unless you expressly want to work.
  • In Austria, the time window for the first midwife consultation and the health consultation in the Parent-Child Pass (Eltern-Kind-Pass) closes with this week.

Get checked right away: heavy bleeding, severe or persistent abdominal pain, fever, pain when urinating, or vomiting where you cannot keep anything down.

Gestational sacPlacentaFetus with heartbeat

On ultrasound

  1. 19+0

    Second screening: The head, abdomen, and thigh bone are measured, along with the position of the placenta and the amount of amniotic fluid.

  2. 19+0

    Head circumference is on average about 161 mm.

  3. 19+0

    Thigh bone (femur) measures on average about 29 mm.

In Austria, the second ultrasound between the 18th and 22nd week of pregnancy also measures the length of the cervix. In Switzerland, the second ultrasound takes place between the 20th and 23rd week.

Frequently asked questions about the 20th week of pregnancy

Which month is the 20th week of pregnancy?

The last week of the 5th month of pregnancy, in the 2nd trimester. By calculation, half of the 40 weeks is reached at 20+0.

Where is the baby in the belly in the 20th week of pregnancy?

The top of the uterus is roughly at the level of the navel; according to the German textbook rule, it is still three finger widths below it. At every prenatal checkup, its height is checked.

Why does the belly get hard in the 20th week of pregnancy?

Usually, these are practice contractions. The uterus tightens briefly, usually without pain and irregularly. If the contractions become regular or painful, get them checked.

Can a baby survive in the 20th week of pregnancy?

Not outside the womb. The German guideline sees no realistic chance before 22+0.

Sources

Updated on 30 October 2026 · Fertilio Editorial Team