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Pregnancy Guide·Second Trimester

Week 17: Fat Stores Begin

Pomegranate (~12cm)·Last reviewed: 17 July 2026
Quick answer

At 17 weeks pregnant you are around four months along and settled into the second trimester. Your baby is about 12cm long from head to bottom, roughly the size of a pomegranate, and weighs about 150g. Brown fat is starting to form under the skin to help control body temperature after birth, and the skeleton is hardening from soft cartilage into bone.

Baby development at week 17

Brown fat is beginning to form under the skin, which will help your baby regulate their body temperature after they are born. The skeleton is gradually hardening from soft cartilage into bone, and the umbilical cord is growing thicker and stronger. Sweat glands are developing, and a waxy protective layer called vernix is starting to form over the skin. Your baby can now yawn, hiccup and make sucking movements, and the tiny bones of the inner ear are taking shape. The placenta is now roughly the same size as your baby and is working hard to deliver oxygen and nutrients.

Your body this week

Your bump is becoming more noticeable as your uterus grows upward, with the top of it now sitting a few centimetres below your navel. Your centre of gravity is shifting, so you may feel a little less steady than usual. Mild aches along the sides of your abdomen, known as round ligament pain, are common as the uterus stretches. Your appetite may increase, which is completely normal. Some people notice skin changes such as darker patches or more visible veins. If this is not your first pregnancy, you might feel the first flutters of movement around now, though many people do not feel them until a few weeks later.

Things to do this week

1
Book your 20-week anomaly scan if you haven't already
2
Consider a maternity support belt if you are experiencing ligament or back pain
3
Start thinking about whether you want to find out the baby's sex at the scan

Frequently asked questions

How many months is 17 weeks pregnant?

At 17 weeks you are about four months pregnant, near the start of your fifth month. Pregnancy is counted in weeks rather than calendar months, so the two do not line up exactly. You are in the second trimester, which many people find the most comfortable stage.

How big is my baby at 17 weeks?

Your baby is around 12cm long from head to bottom and weighs about 150g, roughly the size of a pomegranate. They are growing quickly and starting to lay down fat stores under the skin.

Can I feel my baby move at 17 weeks?

Some people feel the first flutters, known as quickening, around 17 weeks, especially if this is not their first pregnancy. Many do not feel movement until 18 to 24 weeks, and both are completely normal. Early movements often feel like bubbles or gentle taps.

Where is my uterus at 17 weeks?

The top of your uterus is rising toward your navel and now sits a few centimetres below it. As it grows, it gently eases your other organs aside, which is why your bump is becoming more visible.

What are good signs at 17 weeks pregnant?

A growing bump, a healthy appetite and steady energy are all encouraging signs in the second trimester. Symptoms vary from person to person, so having few noticeable symptoms is also perfectly normal. Your midwife is always there if you have questions.

What happens at 17 weeks pregnant?

Your baby is developing fat stores and their skeleton is hardening from cartilage to bone. They are about 12cm long from head to bottom. You may feel the first movements around now if this is not your first pregnancy.

Related reading

Baby Development
When Do You Feel Your Baby Move for the First Time?

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