Second trimester
17 weeks pregnant
Baby is about the size of a pear.
Week 17 of 40 · in your second trimester · Updated
Your baby this week
Baby is putting on fat for the first time. Skin is translucent and wrinkly.
- Body fat (adipose tissue) starts to develop — important for regulating temperature after birth.
- Sweat glands are forming under the skin.
- Baby's skeleton is changing from rubbery cartilage to bone.
Your body this week
Round-ligament pain (sharp twinges in your sides) is common.
- Your center of gravity is shifting — you may notice changes in balance.
- Heartburn can intensify because the growing uterus puts pressure on your stomach.
- Vivid, sometimes weird dreams are common.
Common symptoms
- Heartburn
- Vivid dreams
- Sweating more
- Stretching skin (itchy)
- Round-ligament pain
Things to do this week
- Sleep on your left side (better circulation to baby)
- Use pillows to support your belly
- Wear comfortable, low-heel shoes
For partners this week
Better sleep setup
- Pick up a body pillow or some extra pillows for side sleeping.
- Keep dinners lighter and earlier if heartburn is flaring.
Typical visits around this week
Based on a typical schedule in Ontario. Your doctor or midwife sets the actual timing.
Routine check-ups (about every 4 weeks)
Weeks 12–28
Check-ups are often about every 4 weeks until around 28 weeks. Your provider usually checks your blood pressure, weight and urine, listens to the baby's heartbeat and measures your growing belly. Some people need more visits.
Questions to ask →Questions to ask ↑
- Is my blood pressure and weight gain on track?
- Is this symptom I've been having normal?
- What should I be doing about exercise, work or travel right now?
- What's coming up before my next visit?
Coming up
Anatomy (detailed) ultrasound
Weeks 18–22
A detailed ultrasound, usually at 18–22 weeks, that looks at the baby's brain, face, heart, spine, organs, arms and legs, and checks growth and where the placenta is.
Questions to ask →Questions to ask ↑
- Can my partner come, and can we have pictures?
- Where is the placenta, and does that matter for us?
- When will my provider go over the results with me?
- If we want to know the sex, can it be shared at this scan?
A flu shot and a COVID-19 vaccine are recommended at any stage of pregnancy. The flu shot is given during flu season, so the timing depends on when you're pregnant.
When to call your doctor or midwife
Bleeding, fluid leaking, a bad headache or vision changes, or baby moving less than usual all need a call. See the warning signs and who to call →
Follow your pregnancy week by week in MyBabyBase.
A due-date countdown, a mood and symptom journal, appointments, and a safe place for your documents — all in one hub.
Jump to a week
Further reading from health authorities
- Pregnancy — Government of Canada (Public Health Agency of Canada)
- Your pregnancy — Pregnancy Info, from the Society of Obstetricians and Gynaecologists of Canada (SOGC)
- Week-by-week guide to pregnancy — NHS (UK)
- Pregnancy — American College of Obstetricians and Gynecologists (ACOG)