17 weeks pregnant

17 weeks pregnant is about 4 months. It falls in the fourth month of pregnancy. You are in week 17 of 40, in the second trimester. Here is what is happening with your baby and your body this week.

Your baby at 17 weeks

Fat stores are starting to build up under the skin. The umbilical cord is growing stronger.

Your baby is starting to lay down fat, which will help with energy and keeping warm after birth. Some of this is a special type called brown fat, which helps newborns produce heat. For now the skin is still thin and see-through, and your baby looks quite lean.

The skeleton continues to change from soft cartilage to bone, and the umbilical cord is becoming thicker and stronger as it carries more blood between the placenta and your baby. Sweat glands are beginning to develop in the skin.

Your baby's joints are moving freely, and they are rolling, kicking, and flexing their arms and legs in the amniotic fluid. Their heart rate is now regulated by the brain rather than beating at a fixed rhythm, an early sign of the nervous system taking control of body functions.

Your body at 17 weeks

Your appetite may increase. You may notice your center of gravity shifting.

As your bump grows, your center of gravity moves forward, which can affect your balance and put strain on your lower back. You may find you're hungrier than before, so planning nutritious snacks can help. Weight gain usually becomes steadier from now on. As your skin stretches over your belly, breasts, and hips, you may notice itching or the first faint stretch marks. Some people also sweat more and have more vivid dreams, both of which are linked to hormone changes and are common in pregnancy.

Your belly at week 17

In month 4 (weeks 14–17) your lower belly starts to round out. In a first pregnancy many people start to show around 16 weeks or a little later. At about 16 weeks the top of the uterus sits roughly halfway between your pubic bone and your belly button.

Belly size and shape vary a lot depending on your build, whether this is your first pregnancy, your baby's position and the amount of amniotic fluid. At checkups your doctor or midwife may measure your fundal height to track your baby's growth, and may arrange an ultrasound if the measurement is quite different from what they expect.

Symptoms at 17 weeks pregnant

• Increased hunger
• Lower back aches
• Itchy skin on the belly
• Early stretch marks
• Sweating more than usual
• Vivid dreams

Common symptoms in the second trimester

The second trimester runs from week 14 to week 27. Nausea often eases, energy returns, your bump starts to show, and you will begin to feel your baby move. Not everyone has every symptom, and it is normal for symptoms to come and go. Common ones include:

• A growing bump and weight gain
• First baby movements, usually felt between weeks 16 and 25
• Round ligament pain (sharp pains low in the belly or groin)
• Heartburn and indigestion
• Back ache
• A blocked nose or nosebleeds
• Leg cramps
• Skin changes such as a dark line on the belly or darker patches on the face

Read the full second trimester guide.

When to call your doctor or midwife

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Frequently asked questions

How big is my baby at 17 weeks pregnant?

At 17 weeks pregnant, your baby is about the size of a pear. That is about 13 cm (5.1 in) from crown to rump, weighing about 140 g (5 oz).

How big is my belly at week 17 of pregnancy?

In month 4 (weeks 14–17) your lower belly starts to round out. In a first pregnancy many people start to show around 16 weeks or a little later. At about 16 weeks the top of the uterus sits roughly halfway between your pubic bone and your belly button. Bump size, shape and when you start to show vary a lot from person to person.

How much weight should I have gained by 17 weeks?

There is no single right number. Recommended total weight gain depends on your weight before pregnancy, and many people gain only a small amount in the first trimester. From the second trimester on, gain tends to become more steady. Your doctor or midwife can tell you what range is healthy for you and keep track of it at your visits.

Is it safe to travel or fly at 17 weeks?

For most people with an uncomplicated pregnancy, the second trimester is often the most comfortable time to travel. Check your airline's rules and your travel insurance, walk around and drink water on long journeys to lower the risk of blood clots, and wear your seatbelt below your bump. Check whether your destination has any infection risks for pregnant travelers, and talk to your provider first if you have complications.

Can I prevent stretch marks?

Stretch marks are very common and depend largely on genetics and how quickly your skin stretches, so no cream has been proven to prevent them. Moisturizing can still ease itching and dryness. Gaining weight gradually, as advised by your provider, may help. Most stretch marks fade to lighter, less noticeable lines in the months after birth.

What trimester is 17 weeks pregnant?

Week 17 is in the second trimester, which covers weeks 14 to 27.

How many months is 17 weeks pregnant?

17 weeks pregnant is about 4 months. It falls in the fourth month of pregnancy. The fourth month covers weeks 14 to 17. Pregnancy is about 40 weeks, or roughly 9 months, counted from the first day of your last period.

This page is general educational information and is not a substitute for advice from your doctor or midwife. Every pregnancy is different, and baby sizes are approximate averages. Last updated 2026-11-07. See our medical disclaimer.