Pregnancy week 17: the first layer of baby fat
Until now the baby was skinny by design — from this week the first fat layer goes on. The chubby cheeks of the birth photos start here.
The foundation of chubby cheeks
The newborn picture in every head — full cheeks, round arms — is made of fat, and its first layer starts now. Not for looks: that layer is the newborn's main heating system.
Right now fat is a trace of the baby's weight; by birth it will be a solid share. The filling of the wrinkled suit has begun.
Your own frame is under renovation too — the hormone relaxin is loosening joints so the pelvis can open for birth. Its side effect: new complaints from the back, hips and sometimes knees. This week is about their management.
Your baby this week
The baby is pear-sized — thirteen centimetres, about a hundred and forty grams — and now outweighs its own placenta for the first time.
The umbilical cord is thickening and toughening — two arteries, one vein; the lifeline of this whole story. Sweat glands are starting.
The skeleton continues its cartilage-to-bone conversion, and as the hearing bones set, the baby is entering the world of sound — your heartbeat, your stomach's gurgles, the whoosh of your blood.
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Changes in your body
The weight gain is showing now, and with it the walk changes — the centre of gravity shifts forward, and the body leans back to compensate. That lean is where the backache lives.
The fix is posture: stand tall, sit with back support, lift with the knees not the waist, and give high heels a few months off.
Side-sleeping should become the habit now, with the knee pillow as its best friend. Waking up on your back happens — don't panic; roll to the side and carry on. The body itself won't tolerate long flat-lying much longer.
What to do this week
The anomaly scan date is fixed, yes? The window opens next week. It's a long scan (30-40 minutes) — go unhurried, and take your husband; this one is worth watching together.
Add ten minutes of daily back care — cat-cow stretches, wall squats, pelvic tilts. Better than any video: one physiotherapy session to learn the form; it pays for nine months.
The plate now guards three things at once: iron (greens, gud, IFA), calcium (dairy, tablet at its own hour), protein (dal/curd/eggs at every meal). This trio rides to the end now.
Piles prevention starts today: water all day, fibre on the plate, and no phone-scrolling on the toilet — time on the seat is pressure on the veins.
Week 17 at a glance
The week's essentials in one place. Your doctor may adjust these for your situation.
| Item | In week 17 |
|---|---|
| Main event | First fat layer — the heating system begins |
| Baby's size | Pear — 13 cm, 140 g |
| Forming | Tougher cord, sweat glands, hearing bones |
| Possible symptoms | Backache's arrival, loosening joints, changed gait |
| Next week | The anomaly scan window opens |
| Daily trio | Iron + calcium + protein — to the finish |
| New habit | Ten minutes of back exercises; knee pillow |
When to see a doctor at once
The standing list — bleeding, persistent pain, high fever, urinary burning, sudden watery discharge, one-sided calf swelling: same-day.
Dizziness has a new cause now — lying flat lets the uterus press the big vein and blood pressure dips. If it happens, roll left and it settles. But repeated standing dizziness or fainting can also be anaemia talking — mention it before the next visit.
This article is general information only and no substitute for personal medical advice. The person who can advise you knowing your health, your medicines and your previous pregnancies is your obstetrician, or the doctor at your nearest health centre.
Work out your due date
Enter the first day of your last period and your cycle length — your estimated due date, this week's count and the anomaly scan window all appear right here.
It is only an estimate — most babies aren't born on the exact date. A first-trimester scan dates a pregnancy more accurately; in the end, your doctor's date is the one that counts.
Frequently asked questions
How much weight should I have gained by now?
Depends on the starting build, but roughly: one-two kilos in the first trimester (or none, with nausea), then about half a kilo a week from here. Your own target is the doctor's call — not the neighbourhood's comparison.
I miss sleeping on my stomach
harmful? — Soon the bump makes it impossible anyway, and until then the baby is fully cushioned. Try the halfway tilt — half side, half front, pillow-propped.
My heart beats faster these days
okay? — Pregnancy circulates more blood; ten-fifteen extra beats a minute is normal. A racing heart at rest, breathlessness or chest pain is a different story — report that.
Night leg cramps
what helps? — The classic pregnancy cramp. Pull the toes up toward you with the leg straight — it releases. Prevention: daytime water, evening calf stretches, and a word with the doctor about calcium-magnesium.
Sources
Every clinical figure on this page is taken from the guidelines below. Where our numbers and your doctor's differ, ask which guideline they follow.
- WHO. WHO recommendations on antenatal care for a positive pregnancy experienceBacks the article's guidance on iron and folic acid (IFA) supplementation during pregnancy, routine anomaly scanning, and gestational weight gain as components of standard antenatal care.
- NICE. Antenatal care (NG201)Supports the recommendation to sleep on the side from mid-pregnancy, the description of the anomaly scan window (typically offered around 18–20+6 weeks), and the advice to report sudden watery discharge, one-sided calf swelling, persistent pain, or bleeding on the same day.
- NHS. Back pain in pregnancyBacks the posture advice (standing tall, back-supported sitting, lifting with the knees), the recommendation to avoid high heels, and the suggestion of exercises such as pelvic tilts and physiotherapy referral for pregnancy-related back pain.
- UNICEF. Nutrition during pregnancySupports the broader dietary guidance on protein, iron, and calcium intake during pregnancy for maternal and fetal development in the Indian context.
- ACOG. ACOG Committee Opinion No. 804: Physical Activity and Exercise During Pregnancy and the Postpartum PeriodSupports the page's advice on back-care exercises (pelvic tilts, cat-cow stretches), posture correction, and physiotherapy referral to manage pregnancy-related back and hip pain.
- ACOG. Sleeping Positions During Pregnancy (FAQ)Supports the page's advice to adopt left-side sleeping from mid-pregnancy and that waking on one's back is not an emergency — rolling to the side is sufficient — and that supine position can cause the uterus to compress the inferior vena cava, causing dizziness.
Reviewed by
- Nakul Phatak — CEO, theAsianparent India & IndonesiaHead of theAsianparent India; father of one
- Roshni Chugani — Head of Marketing, theAsianparent India & Singapore12 years in the mother-and-baby space; mother of two
Published by: theAsianparent editorial team
