23rd week: Sleep and wakefulness alternate

Weeks and days
22+0 to 22+6
Month
6
Trimester
2

This week, the fetus grows from about 191 to 204 millimeters and weighs around 570 grams by the end. From about the end of the week, sleep and wake phases visibly alternate. At 22+0, the threshold begins from which a baby born very early can survive in individual cases.

A whole green coconut in its husk lies in an open palm on beige linen
Coconut200 to 300 mm, the size of your baby at the end of the week

Week 23 of 40

Calculate your week
1st trimester2nd trimester3rd trimester

How big is the fetus?

050100150200250300 mm21st week166 to 17922nd week179 to 19123rd week191 to 20424th week204 to 213Coconut at the same scale

191 to 204 mm

By the end of the week, the fetus is about the size of a coconut in its green husk. From head to heel, it measures about 29 centimeters.

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 coconut in its husk is 200 to 300 mm long.

This week

Your baby

  • The skin is wrinkled because the fat tissue underneath is still missing.
  • Hiccups occur, at 10 to 21 hiccups per minute. You may feel them as a rhythmic tapping.
  • The skull bones have not yet fused and can shift against each other.

Your body

  • The top of the uterus reaches about to the navel. The distance to the pubic bone is on average 23 cm by the end of the week.
  • Over the next few weeks, pain at the ribs, shortness of breath, and the first drops of colostrum may appear.
  • With a normal weight before pregnancy, a gain of about 4.1 to 5.6 kilograms by the end of the week is usual.

What matters now

  • In Germany, there is no appointment scheduled this week. From next week, another antibody screening test follows, and from 24+0 the glucose test.
  • In Switzerland, it is the last week for the second routine ultrasound.
  • If amniotic fluid leaks or regular, painful contractions start, go to the hospital immediately.

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. 22+0

    Head circumference is on average about 198 mm.

  2. 22+0

    Abdominal circumference measures on average about 173 mm.

  3. 22+0

    Thigh bone (femur) measures on average about 38 mm.

In Germany, no ultrasound paid for by health insurance is scheduled until the third screening from 28+0, unless there is a reason for one.

Frequently asked questions about the 23rd week of pregnancy

Which month is the 23rd week of pregnancy?

The 6th month of pregnancy, in the 2nd trimester. Figures such as 22+3 weeks also belong to the 23rd week of pregnancy.

Can a baby survive in the 23rd week of pregnancy?

A small one. From 22+0, life-sustaining treatment is given in Germany only at the express wish of the parents. In an analysis of international studies cited by the German guideline, about 24 out of 100 babies born in this week survived. In Switzerland, babies born before 23+0 usually receive only palliative care.

How long does the baby sleep in the 23rd week of pregnancy?

There is no reliable number of hours. From about the end of this week, sleep and wake phases can be recognized; clearly defined sleep states only appear toward the end of pregnancy.

Is it normal for baby movements to vary in the 23rd week of pregnancy?

Yes. Activity varies over the course of the day, and breaks of several minutes are normal. If the movements become noticeably fewer than usual, call your midwife or the hospital.

Sources

Updated on 30 October 2026 · Fertilio Editorial Team