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23 Weeks Pregnant: Fingerprints Form & the Lungs Begin to Prepare

Medically reviewed by

Sarah Riffle, RN Jul 30, 2026

Line illustration of a halved papaya with its seeds: at 23 weeks pregnant your baby is about the size of a papaya, roughly 19 to 21cm crown to rump

Line drawing of a 23-week foetus with an open palm, the ridges that become fingerprints now forming

Line drawing of a woman's torso at 23 weeks pregnant, showing the enlarged uterus and a full rounded bump

Your baby is the size of a

Papaya

Between ~460g (week 22) and 630g (week 24)

~19–21 cm / ~7.5–8.3 in

Key Takeaways

At 23 weeks pregnant, your baby's fingerprints and footprints are beginning. Mayo Clinic says ridges form in the palms and soles that will create the foundation for fingerprints and footprints, and your baby starts to have rapid eye movements.

The lungs begin an important preparation. Mayo Clinic explains they start making surfactant, which lets the air sacs inflate and keeps the lungs from collapsing, and notes some babies born this far along may be able to survive outside the uterus.

This is a good week to learn the signs of preterm labour. SOGC says to contact your provider right away for regular contractions under 10 minutes apart, cramping, pelvic pressure, leaking fluid, backache that comes and goes, or bleeding.

Your Baby at 23 Weeks: Development & Growth

At 23 weeks pregnant, your baby's fingerprint and footprint ridges are forming, rapid eye movements are beginning, and the lungs are starting to make surfactant, according to Mayo Clinic. Mayo Clinic gives no exact size this week — it places the baby at about 190 millimetres and 460 grams at week 22, and about 210 millimetres and 630 grams at week 24.

The signature detail this week is, quite literally, a signature. Mayo Clinic explains that at 23 weeks "ridges also form in the palms of the hands and soles of the feet that will create the foundation for fingerprints and footprints." A pattern no one else will ever have.

The eyes are busy too. Mayo Clinic notes that this week "your baby starts to have rapid eye movements" — the flickering, closed-eye motion linked to sleep. Small rhythms are settling in.

The lungs begin a job that matters enormously later. Mayo Clinic explains that "the lungs are starting to make a substance called surfactant," which "allows the air sacs in the lungs to inflate and keeps the lungs from collapsing and sticking together when they deflate." It is early groundwork for a first breath.

On size, an honest note. Mayo Clinic does not give a measurement at week 23. It puts the baby at "about 7 1/2 inches (190 millimeters) long from crown to rump" and "about 1 pound (460 grams)" at week 22, and "about 8 1/4 inches (210 millimeters)" and "more than 1 1/3 pounds (630 grams)" at week 24 — so your baby this week sits somewhere between those two. Length is still crown to rump, because the legs stay curled.

Your Body at 23 Weeks: Symptoms & Changes

At 23 weeks pregnant, many mothers are in a settled stretch of the second trimester, though the common discomforts can still come and go. SOGC lists breast changes, constipation, backaches, headaches, mood swings and leg cramps among them. Movement is usually well established by now, and this is a good week to notice your baby's pattern. Every pregnancy is different.

Movement tends to feel real and regular by now. SOGC notes that "by 24 weeks, almost all women will feel their baby's movements in a predictable way," and that "your perception of your baby's movements is one of the strongest indicators of your baby's wellbeing." A pattern is something you can start to know.

That pattern is worth paying attention to. SOGC advises that "if you ever have concerns regarding your baby's movement pattern, you should have the baby assessed as soon as possible," and that mothers "should always trust their intuition." You know your baby better than anyone.

Symptoms haven't necessarily left. SOGC lists tender or swollen breasts, "constipation, gas or bloating," "backaches and headaches," mood swings and cramping among the common discomforts of pregnancy. Any of these can still be part of your week.

One symptom worth flagging is mood. SOGC notes that mood swings "are not usually severe," but adds that "depression or disruptive mood swings are not normal and it is important to seek help for these more serious concerns." That is a conversation worth having, not carrying alone.

And a reminder that steadies almost everything else: SOGC opens its symptoms guidance with the plain truth that "every pregnant woman is different." Some sail through; some don't. Both are normal.

What to Do at 23 Weeks Pregnant

NUTRITION AT 23 WEEKS PREGNANT

Keep the second-trimester increase modest. SOGC states: "In the second trimester you need about 340 extra calories per day," noting this "generally equates to 2 or 3 additionally servings from any of Canada’s Food Guide’s food groups" — for example a piece of toast and a cup of milk. Quality over quantity.
Stay on top of iron. SOGC advises increasing "your daily iron intake to 27mg daily during the final six+ months of pregnancy to support an increase in red blood cells and fetal tissues" — and notes that, "like most women, you may need a good supplement to meet this need."
Mind your fibre. SOGC advises you’ll "need 2-3g more of fibre in your diet daily for a total of 28g," noting this "helps reduce constipation and may help to reduce the risk of developing high blood pressure." A practical answer to a common week-23 complaint.

WHAT SUPPLEMENTS TO TAKE AT 23 WEEKS PREGNANT

Keep taking 400mcg of folic acid daily. The Public Health Agency of Canada states that "a daily multivitamin with 400 mcg (0.4 mg) of folic acid is recommended for anyone who could become pregnant," and advises: "Continue taking folic acid throughout your pregnancy and while breastfeeding."
Don’t raise your folic acid dose on your own. The Public Health Agency of Canada advises: "You should not increase your dose of folic acid beyond 1 mg per day without talking to your health care provider." A higher dose is a conversation, not a decision for the supplement aisle.
Check your prenatal for choline. SOGC notes that "choline intake above 450mg a day is linked to improved fetal stress responses and a reduced risk of neural tube defects," and adds that "this vitamin may not be found in your prenatal daily vitamin" — so it is worth reading the label.

LIFESTYLE TIPS AT 23 WEEKS PREGNANT

Keep moving — aim for at least 150 minutes a week. SOGC advises that "pregnant women should accumulate at least 150 minutes of moderate intensity physical activity each week," spread across "at least 3 days a week, and up to 7 days a week." Walking, swimming and stationary cycling are all good options.
Build in pelvic floor exercises. SOGC notes that "pelvic floor muscle training (e.g., Kegel exercises) can be performed every day to reduce the risk of urinary incontinence." Easy to fold into a daily routine.
Keep caffeine to 300mg a day. Health Canada recommends a maximum daily caffeine intake of 300 mg for people who are pregnant. For reference, Health Canada puts one 8oz (237ml) cup of brewed coffee at about 135mg — so roughly two cups is the ceiling, and that total includes tea, cola and chocolate.
Learn the signs of preterm labour. You are not expecting them, and most tightenings are harmless — but SOGC says knowing what to watch for matters because "there are some important interventions to help prevent some of the consequences associated with preterm birth, but they have to be done early to be most effective." See the section below.

When to Contact Your Doctor or Midwife

Most of week 23 is milestones, not alarms. But a few symptoms should always be checked. Contact your doctor, midwife or other health care provider if you experience:

Any sign of preterm labour. SOGC advises contacting your health care provider right away if you have any of the following: backache that comes and goes; regular contractions less than 10 minutes apart; cramping in your lower abdomen; fluid leaking from your vagina; pressure in your pelvis or vagina; or vaginal bleeding. SOGC defines preterm labour as regular contractions that lead to changes in the cervix before term (37 weeks).
Regular contractions that don't ease. SOGC is direct: it is very important to go to the hospital if you have regular contractions at any time before 37 weeks that don't go away when you change your activity. It adds a warning worth taking to heart — staying home thinking this couldn't possibly be labour because it is too early is dangerous.
Any vaginal bleeding. SOGC advises: "It's important for you to take any vaginal bleeding seriously. Contact your health care provider as soon as you notice any bleeding." If you have signs of infection like fever or heavy bleeding, SOGC says you should see your care provider right away. If bleeding is heavy or you feel very unwell, seek emergency medical care immediately.
Any concern about your baby's movements. SOGC advises that "if you ever have concerns regarding your baby's movement pattern, you should have the baby assessed as soon as possible," and that mothers should always trust their intuition. A change from your baby's usual pattern is worth acting on.
Persistent low mood or disruptive mood swings. SOGC advises that "depression or disruptive mood swings are not normal and it is important to seek help for these more serious concerns."

أسئلة مكررة

How big is my baby at 23 weeks pregnant?

Mayo Clinic does not give an exact size at week 23. It places the baby at "about 7 1/2 inches (190 millimeters) long from crown to rump" and "about 1 pound (460 grams)" at week 22, and "about 8 1/4 inches (210 millimeters)" and "more than 1 1/3 pounds (630 grams)" at week 24 — so at 23 weeks your baby sits somewhere between those figures, roughly 190 to 210 millimetres crown to rump and about 460 to 630 grams.

Can a baby survive if born at 23 weeks?

Some can. Mayo Clinic states plainly that "if born preterm, some babies this far along in pregnancy may be able to survive outside the uterus." This is a genuine turning point in pregnancy. It is also, for the vast majority of mothers, information you will never need — the aim of knowing the signs of preterm labour is simply so you can act early if they ever appear.

What are the signs of preterm labour?

The Society of Obstetricians and Gynaecologists of Canada (SOGC) says to "contact your health care provider right away if you are having any of the following: Backache that comes and goes; Regular contractions less than 10 minutes apart; Cramping in your lower abdomen; Fluid leaking from your vagina; Pressure in your pelvis or vagina; Vaginal bleeding." SOGC also advises that "it is very important to go to the hospital if you have regular contractions at any time before 37 weeks that don’t go away when you change your activity," and warns that "staying home thinking that this couldn’t possibly be labour because it is too early is dangerous."

What is surfactant, and why does it matter at 23 weeks?

Surfactant is a substance the lungs make that lets them work. Mayo Clinic explains that at 23 weeks "the lungs are starting to make a substance called surfactant," which "allows the air sacs in the lungs to inflate and keeps the lungs from collapsing and sticking together when they deflate." It is one of the reasons the lungs are still maturing well past this point.

How much caffeine is safe at 23 weeks pregnant?

Health Canada recommends a maximum daily caffeine intake of 300 mg for people who are pregnant. Health Canada puts one 8oz (237ml) cup of brewed coffee at about 135mg, so roughly two cups a day is the ceiling — and that total should include tea, cola and chocolate, which also contain caffeine.

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