31st week: The pupils respond to light

Weeks and days
30+0 to 30+6
Month
8
Trimester
3

This week, the fetus gains from about 1,520 to 1,710 grams. Its pupils now begin to respond to light. Time to prepare for maternity protection and maternity benefit.

A whole pale green honeydew melon lies on an open hand
Honeydew melonaround 1.7 kg, the weight of your baby at the end of the week

Week 31 of 40

Calculate your week
1st trimester2nd trimester3rd trimester

How big and how heavy is the fetus?

050100150200250300 mm29th week250 to 25930th week259 to 26731st week267 to 27632nd week276 to 284

267 to 276 mm

By the end of the week, the fetus weighs about as much as a honeydew melon. From head to heel, it measures about 39 centimeters.

Crown-rump length according to the values from Archie et al. 2006, weight according to the WHO growth charts. A honeydew melon weighs 1.5 to 3 kg.

This week

Your baby

  • The pupils begin to respond to light. By the 36th week of pregnancy, all babies can do this.
  • Fat is deposited under the skin all over the body, and the baby becomes more rounded.
  • If you place warm hands on your belly and move them slowly, the baby may follow them.

Your body

  • Climbing stairs is tiring. For most, however, shortness of breath no longer increases after this week.
  • Tingling or numbness in both hands is often due to carpal tunnel syndrome. A splint at night can help.
  • Poor sleep and vivid, sometimes unsettling dreams are common.

What matters now

  • In Germany, maternity protection begins at 34+0. You receive the certificate of your due date for your health insurance fund and employer about seven weeks before the due date.
  • In Austria, maternity protection begins as early as 32+0, that is, next week. Get the medical confirmation for the maternity allowance now.
  • If the other parent is to take parental leave right after the birth, the employer must receive the notice no later than seven weeks before the due date.

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. 30+0

    Head diameter from temple to temple measures on average about 77 mm.

  2. 30+0

    Abdominal circumference measures on average about 260 mm.

  3. 30+0

    Thigh bone (femur) measures on average about 56 mm.

In Germany, the third basic ultrasound is still possible until 31+6, that is, until the end of next week.

Frequently asked questions about the 31st week of pregnancy

Which month is the 31st week of pregnancy?

The 8th month of pregnancy, in the 3rd trimester. Figures such as 30+4 weeks also belong to the 31st week of pregnancy.

Can a baby survive in the 31st week of pregnancy?

Yes, a very good one. In England, 97 out of 100 babies who were born in this week and admitted to a neonatal unit survived to discharge.

How often are practice contractions normal in the 31st week of pregnancy?

Occasional, short, and usually painless contractions are normal. If they come more than three times an hour or around ten times a day and do not ease with rest, call your doctor or midwife.

Is a weight of 1,800 grams normal in the 31st week of pregnancy?

Yes. At the end of the week, 80 out of 100 babies weigh between about 1,470 and 1,960 grams. Whether your baby is growing well is shown by the trend on ultrasound.

Sources

Updated on 30 October 2026 · Fertilio Editorial Team