September 10, 2026

Pregnancy week 17: symptoms, baby size and tips

Pregnancy week 17 keeps you right in the second trimester, that stage when many women finally feel more energy and their bump is more and more present. Your baby is now about 13 centimetres, roughly the size of a pear, and this week they’re doing something really important: they start to store fat, practise breathing and their skeleton keeps getting stronger. Let me walk you through it, as always.

If you’re coming from pregnancy week 16, you’re on a great track. And to have the whole path at hand, check out our pregnancy week by week guide.

What is pregnancy week 17?

As always, pregnancy weeks are counted from the first day of your last period (LMP), not from conception. In week 17 you’re about 15 weeks from fertilisation, in your fourth month (weeks 14–17) and still in the second trimester, which runs from week 13 to week 28.

By now the placenta is fully established: it produces the hormones that keep your pregnancy going and feeds your baby through the umbilical cord, which is already thicker and stronger. Your uterus keeps rising up, so your bump is clearly visible and you usually have less pressure on your bladder than in the early months.

What can you see on a week 17 scan?

This still isn’t a routine scan week for everyone, but if you have one, it’s a lovely moment because your baby doesn’t stay still for a second:

Their skeleton keeps hardening: the cartilage is turning into bone, especially in the limbs, and their back is getting stronger.
They practise breathing: their diaphragm moves and makes breathing movements, although they’re not breathing real air yet (oxygen comes from the placenta and umbilical cord).
They start to store fat: brown fat forms, which after birth will help them keep warm. Their skin is slowly becoming less see-through.
They swallow amniotic fluid: they swallow it and their kidneys make urine, which goes back into the amniotic fluid. Meconium also starts to form in their gut.
They hear you brilliantly: the tiny ear bones are becoming firmer and their hearing keeps sharpening. They pick up your voice, your heartbeat and the sounds of your digestion.
They pull faces and suck their thumb: the mouth muscles let them suck their thumb, a reflex that gets them ready to breastfeed after birth.

If you haven’t taken a test yet, don’t worry: your hCG is still high and any test is very reliable. You can take our free online pregnancy test for guidance with your symptoms, and if you fancy a distraction, try our finger pregnancy test game: it’s just a game, not a real test.

What symptoms are normal in week 17?

Every pregnancy is different, but in week 17 most women are still in a fairly easy place:

Your bump keeps growing: your waistline is disappearing and you may need comfier clothes. Your uterus is clearly noticeable above your pubic bone.
You may start to feel movement: if you’ve been pregnant before, you might already notice some fluttering. If it’s your first pregnancy, the first movements usually come between weeks 18 and 22.
Heartburn or indigestion: progesterone still relaxes the stomach valve and acid can come up. Eating little and often helps.
Twinges or cramps in your lower belly: the round ligament stretches as your uterus grows. That’s normal, but if the pain is strong or persistent, talk to your doctor.
Lower-back pain: with your bump out front, your lower back works harder. Walking, swimming and good posture help.
Nasal congestion and light nosebleeds: pregnancy rhinitis is still common. If the bleeding is heavy or ongoing, talk to your doctor.
Skin changes: the linea alba, dark spots and darker areolas can keep appearing. All of it is normal.

Hardly any symptoms? Also completely normal. Every woman experiences each week in her own way.

How big is the baby in week 17?

Week 17 baby, the size of a pear

The baby in week 17 measures about 13 centimetres (from head to toe) and weighs around 100 to 140 grams, roughly the size of a pear. And even though they’re still small, they’re full of activity this week:

Their skeleton keeps calcifying: the bones of the limbs and spine are slowly hardening.
Their muscles get stronger: they control their movements better, stretch their arms and legs and unfold.
They start to store brown fat, which will help them stay warm after birth. Their skin becomes less transparent.
They practise breathing: their diaphragm moves up and down, getting ready for that first cry a few months from now.
They swallow amniotic fluid and their digestive system starts to make meconium.
Their hearing improves: the inner ear is already well developed and they pick up your voice better every day.
They suck their thumb and pull faces with their mouth, getting ready for breastfeeding.

Fun fact: even though they move a lot, it’s very likely you still can’t feel their movements, especially if it’s your first pregnancy. First-time mums usually feel the first movements between weeks 18 and 22. Don’t worry if you notice nothing yet: it’s completely normal.

Tips for week 17

Don’t expect to feel movements yet: if you notice nothing, it doesn’t mean something’s wrong. First-time mums usually feel movement around weeks 18–22.
Take care of your back: as your bump grows, try to sit and walk with a straight back and avoid lifting heavy things. Gentle stretching helps with lower-back discomfort.
Sleep on your side, preferably the left: it improves circulation to the uterus and helps with heartburn. Put a pillow between your knees for extra comfort.
Keep taking folic acid: although the neural tube has closed, it’s still important. I explain everything in folic acid in pregnancy.
Take care of your diet: add calories in a healthy way with fruit, vegetables, protein and hydration. Keep avoiding alcohol, smoking and raw foods.
Exercise gently and calmly: walking, swimming or prenatal yoga are great for your mood and prepare your body for birth.
Don’t self-medicate: always ask your doctor before taking anything.
Work out your due date with the gestogram and track your week with how many weeks pregnant am I.

FAQ

What month am I in during week 17?

You’re in your fourth month of pregnancy (weeks 14–17), within the second trimester. You’re about 15 weeks from fertilisation.

How big is the baby in week 17?

About 13 centimetres from head to toe and between 100 and 140 grams: roughly the size of a pear. Their skeleton is getting stronger, they practise breathing and they start to store fat.

Why can’t I feel the baby moving yet?

Because they’re still very small and are often in a position where you can’t perceive them. First-time mums usually feel the first movements between weeks 18 and 22. It’s completely normal.

Can the baby hear me in week 17?

Yes, better and better. The tiny ear bones are becoming firmer and their hearing keeps maturing: they pick up mainly your voice and your heartbeat.

Is heartburn normal in week 17?

Yes, it’s very common: progesterone relaxes the stomach valve and acid can come up. Eating little and often, and not lying down right after eating, usually helps.

What are those twinges in my lower belly?

Usually it’s the round ligament, which stretches as your uterus grows. It’s normal and harmless. If the pain is strong, persistent or comes with other symptoms, talk to your doctor.

Sources

Remember this article is for information only. If you have questions about your health or think something might be off, talk to your doctor. They can advise on the right tests and support you through this special time ❤️.