17 weeks pregnant: baby, body and what to expect

Trimester 2 of 3About 4 months23 weeks to go

Week 17 of pregnancy: baby is about the size of a turnip

Week 17 at a glance

At 17 weeks, the fetus is often about 13–14 cm (5.1–5.5 in) long, roughly the size of a turnip. The skeleton begins to harden as cartilage gradually turns into bone, making the body sturdier.

17 weeks pregnant is about 4 months. You are in month 4 of pregnancy and the second trimester.

Your baby at 17 weeks

Your Baby's Skeleton Begins to Harden

At 17 weeks, an important change is underway: the skeleton begins to harden.

What that means

The fetus is often about 13–14 cm (5.1–5.5 in) long. Cartilage structures are becoming firmer, and bone tissue is gaining strength, helping the body hold its shape and support movement.

Bones become denser, especially in the arms, legs and spine.
Movements may be more frequent, although they may still not always be felt.
Fat tissue is still building slowly, and muscles continue to strengthen.

At this stage, ultrasound may already show limb movements quite well. If they are not seen during one scan, that does not necessarily mean there is a problem. The baby may simply be in a position that is harder to see.

How this week may feel

In the second trimester, many people feel less nausea, breathe more comfortably and have more energy. Heartburn, stretched ligaments and a sense of heaviness in the abdomen may still continue for some.

Contact your OB-GYN or midwife right away if you have bleeding, severe pain, fever, marked weakness, or a sudden worsening in how you feel.

3D

See week 17 in 3DNova shows how your baby grows each week and keeps a symptom log for your doctor. Try Nova

Your body at 17 weeks

Your Changing Center of Gravity and Walk

Your body is adapting

By week 17, your baby is growing quickly, and your uterus is expanding. This shifts your body's center of gravity, or the point where your weight is balanced.

To help you stay balanced, your lower back may curve more than usual, and your shoulders may shift slightly back. These adjustments can change the way you walk, which is common during pregnancy.

These changes are a normal part of pregnancy. Your body is adjusting to support your growing baby.

Tips for comfort

Choose supportive shoes with low, stable heels.
Pay attention to your posture when you sit and stand.
Try gentle stretching and low-impact activity. Ask your provider which activities are safe for you.

Call your healthcare provider if you have severe lower back pain, sharp pain when you walk, or new swelling in your face, hands, or legs, especially if it is only on one side or comes with calf pain or warmth. Seek care right away for vaginal bleeding, fluid leaking from the vagina, chest pain, or trouble breathing.

Common symptoms at 17 weeks

Lower back ache

As your belly grows, your back may feel tired or sore, especially after standing a long time. Gentle stretching, a supportive chair, and a pillow between your knees when you rest can help.

Feeling unsteady

Your balance may feel off, and you might bump into things more than usual. Taking your time on stairs and wearing shoes with good grip often makes walking feel steadier.

Round ligament pain

You may feel a sharp or pulling pain in your lower belly or groin when you stand up, cough, or change position. Moving slowly and bending at the knees can ease it, and it usually passes.

Leg cramps

Sudden cramps in your calves, often at night, are common in pregnancy. Stretching your calf before bed and staying hydrated may help, and your care team can talk with you if they keep happening.

Stuffy nose

Extra blood flow can cause a stuffy or runny nose that comes and goes. A saline spray or a humidifier at night may make breathing more comfortable.

Skin darkening

A dark line may appear down the center of your belly, and patches of skin on your face or other areas may darken. These changes often fade after pregnancy, and sunscreen can help protect your skin.

Your week 17 checklist

Choose shoes with good arch support and a low, steady heel. Stand tall with your shoulders relaxed and your weight balanced over both feet. Take short walks or gentle stretches to ease back and leg tightness. Keep a water bottle nearby and sip through the day. Write down any new pain, dizziness, or swelling to share at your next visit. Ask your care team about any questions on your mind, big or small.

Tests and appointments

Anatomy ultrasound. This detailed ultrasound is usually offered between 18 and 22 weeks, so it may be scheduled soon to check the baby's growth and organs.

For your partner: You can offer to carry heavier items, handle errands that require a lot of standing, or join short evening walks together. Checking in about how their back and balance feel each day can also help them feel supported.

Questions about week 17

How many months is 17 weeks pregnant?

17 weeks pregnant is about 4 months. You are in month 4 of pregnancy and the second trimester.

What trimester is 17 weeks?

Week 17 is in the second trimester. The first trimester runs through week 13, the second from week 14 to 27 and the third from week 28 until birth.

What is happening with the baby at 17 weeks?

At 17 weeks, the fetus is often about 13–14 cm (5.1–5.5 in) long, roughly the size of a turnip. The skeleton begins to harden as cartilage gradually turns into bone, making the body sturdier.

Why do I feel off balance at 17 weeks?

Your growing uterus shifts your center of gravity, so your body adjusts how it holds you up. Slower movements, supportive shoes, and good posture often help you feel steadier.

Is back pain normal this early?

Yes, many people notice back aches during pregnancy as their belly grows and their posture changes. Let your care team know if the pain is severe, constant, or comes with other symptoms.

What kind of shoes are best during pregnancy?

Shoes with good arch support, a low heel, and a non-slip sole are often a comfortable choice. Avoid shoes that feel tight or make you wobble.