17 weeks pregnant: symptoms and baby development
Fat is forming under the skin.
Second trimesterMonth 45 min read
By Solesia, from public clinical guidanceUpdated
Until now your baby has been all frame and skin, a small person drawn in outline. This week a soft layer begins to gather underneath it, the first of the padding that will keep a newborn warm and give them the round cheeks you are picturing. Something similar is happening to you. The uterus is rising up and out of the pelvis, and the waist you had two weeks ago is quietly going; clothes that closed last week do not close this week. That is the bump arriving, and it is expected. Sleep, worry and the odd stretch mark round out the week.
How big is your baby at 17 weeks
About the size of a pear
4.7 in long·6.4 oz
Baby development at 17 weeks
At 17 weeks your baby measures about 4.7 inches from crown to rump and weighs around 6.4 ounces, roughly a pear. The weight is climbing faster than the length now, because the fat that is beginning to form under the skin adds ounces without adding inches.
That fat matters more than it sounds. Newborns lose heat fast, and this layer, built up week by week from now until birth, is what will keep them warm on the outside. It also feeds the brain and the body in the first days, while feeding is still being worked out. Brown fat, a special kind that burns to make heat, comes a little later.
The eyes are moving under sealed lids, and a loud noise nearby makes them startle. Fingernails have started growing, and the mouth opens and closes as they practice swallowing. The umbilical cord is thicker and stronger, and the placenta, now about as big as the baby, is growing to keep pace with them.
Your body at 17 weeks
The disappearing waist is expected. The uterus has left the shelter of the pelvis and sits below your belly button, and everything around it shifts to make room. Clothes with a soft waistband, or a band that lets you keep your usual pants unbuttoned, get you through the next few weeks without a wardrobe you will need for only a month.
Stretch marks can appear from about now, on the belly first and later the breasts and thighs. They start pink, red or purple and fade to silver after birth. Skin that is stretching at speed is expected to mark, and about eight in ten people get some; creams and oils feel nice and keep the itch down, but no product has been shown to prevent them. Genetics and how fast the bump grows decide it.
Sleep can get harder around now: the bump is in the way, the bladder wakes you, and the mind is busy. About one in five people feel anxious in pregnancy, and hormones can make a small worry loom large at three in the morning. This is expected, and it is also worth saying out loud. Your provider hears it every week and can help, whether with a sleep plan, a referral or a conversation.
Common pregnancy symptoms at 17 weeks
- Trouble sleeping. A bladder that wakes you and a bump in the way. A pillow under the bump and another between your knees.
- Stretch marks. Skin stretching faster than it can adapt. They fade to silver after birth; moisturizer eases the itch.
- Feeling hot. More blood and a faster metabolism. Light layers, and a bottle of water where you sit.
- Indigestion. Hormones slow the stomach and relax its valve. Eat smaller amounts more often; stay upright after.
- Anxiety. Hormones and a lot to think about. Talk to your provider; it is common and it is treatable.
- Round ligament pain. The uterus leaving the pelvis pulls on the cords that hold it. Move slowly, and it passes.
- Nosebleeds. The nose lining is thicker and fuller of blood. Pinch the soft part for ten minutes; a humidifier at night.
When to call your provider at 17 weeks
Two things are worth a same-day call at any point in pregnancy: bleeding that is more than spotting, and pain that is severe or does not ease. From the second trimester, add fluid leaking and any change in your baby’s usual pattern of movement. You do not need to be sure something is wrong to call; that is what the number is for.
What to do at 17 weeks
- Where to give birth. A hospital, a birth center or home with a licensed midwifery practice. Your provider delivers at particular places, so the choice often starts with them; this is a good time to ask.
- Anatomy ultrasound on the calendar. It happens between 18 and 22 weeks, so it is next week at the earliest. If you do not have a date, call this week.
- Sleep set-up. Start getting used to your side now, with a pillow under the bump and one between the knees. By 28 weeks it will be the advice, and by then it will already be a habit.
- A word about how you feel. If worry, low mood or sleeplessness is taking over the week, bring it to your next visit or call sooner. Mental health is part of prenatal care, not an extra.
Common questions at 17 weeks
Is it normal to not feel movement at 17 weeks?
Yes. In a first pregnancy the first flutters usually come between 18 and 20 weeks, and 22 is still within the expected range. People who have been pregnant before often feel them earlier because they know what they are feeling for. A placenta on the front wall of the uterus can cushion the kicks and delay them too.
What do the first movements feel like?
Bubbles, a flutter, a fish turning over, a soft tap from the inside. Easy to mistake for gas at first. They are often clearest when you are lying still after a meal or in a quiet moment in bed. Once you recognize them, they get more frequent and more obvious over the following weeks.
Can I prevent stretch marks?
Not reliably. They come from how fast the skin stretches and from your genes, and no cream, oil or butter has been shown to stop them. Moisturizing does keep the skin comfortable and the itch down, which is reason enough. They fade from red or purple to pale silver in the months after birth.
Why do I feel anxious in the second trimester?
Hormones, broken sleep and the size of what is coming. Anxiety in pregnancy is expected and about one in five people have enough of it to want help. Tell your provider: they can suggest talking therapy, safe medicines where needed, and practical fixes for sleep, and none of it is unusual to ask for.
Written from public clinical guidance, including NHS: Week 17, ACOG: How your baby grows, ACOG: Changes in your body, ACOG: Skin conditions during pregnancy, NHS: Tiredness and NHS: Your baby’s movements. This page is general information, not medical advice, and does not replace your provider.