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12 Weeks Pregnant: The End of Your First Trimester & Your Baby the Size of a Lime

Medically reviewed by

Verena Brehm, Midwife Jul 29, 2026

Line illustration of a lime: at 12 weeks pregnant your baby is about the size of a lime, roughly 6cm

Line drawing of a 12-week foetus with a rounded head, separated fingers and toes and tiny forming fingernails

Line drawing of a woman's torso at 12 weeks pregnant, showing the uterus risen just above the pubic bone

Your baby is the size of a

Lime

~14 g (~½ ounce)

~6 cm / ~2.4 in

Key Takeaways

At 12 weeks pregnant, your baby measures about 6 cm (61 mm) from crown to rump and weighs around 14 g — roughly half an ounce. Fingernails are forming and the face has taken on a more developed profile.

This is the last week of the first trimester. For many women, the worst of the nausea starts to lift: Pregnancy Info, from the Society of Obstetricians and Gynaecologists of Canada, notes that morning sickness usually "eases up by the 12th week."

This is the Canadian window for a first-trimester "dating" ultrasound and for prenatal genetic screening. The Society of Obstetricians and Gynaecologists of Canada recommends a dating ultrasound at 11–14 weeks.

Your Baby at 12 Weeks: Development & Growth

At 12 weeks pregnant, your baby is about 6 cm (61 mm) long from crown to rump and weighs around 14 g — about half an ounce — according to Mayo Clinic. Fingernails are forming and the face has a more developed profile.

Your baby measures about 6 cm this week. Mayo Clinic puts it at "about 2 1/2 inches (61 millimeters) long from crown to rump" and weighing "about 1/2 ounce (14 grams)." That measurement is crown to rump — head to bottom — because the legs are still curled up too tightly to count.

The details this week are tiny but real. According to Mayo Clinic, your baby is "sprouting fingernails," the face "has taken on a more developed profile," and the intestines are now settling into the abdomen.

There is a milestone in the name itself. Mayo Clinic explains that at the 11th week "your baby now is called a fetus" — no longer an embryo. By 12 weeks, the organs formed in the first trimester are in place and will spend the coming months growing and maturing.

The neural tube closed weeks ago, which is why the folic acid you have been taking did its most important work early. The Public Health Agency of Canada explains that "the benefits of taking folic acid to reduce neural tube defects are highest in the very early weeks of pregnancy" — and recommends continuing it "throughout your pregnancy and while breastfeeding." If you're planning to become pregnant and not taking folic acid, start taking it as soon as possible. It should be ideally started at least 3 months before pregnancy.

Your Body at 12 Weeks: Symptoms & Changes

At 12 weeks pregnant, many women notice nausea beginning to ease — Pregnancy Info, from the Society of Obstetricians and Gynaecologists of Canada, says morning sickness "eases up by the 12th week," though for some it lasts longer. Fatigue, tender breasts, frequent urination and mood swings are still common, all listed by Pregnancy Info among the usual symptoms of pregnancy.

The most welcome change this week is often the fading of nausea. Pregnancy Info, from the Society of Obstetricians and Gynaecologists of Canada, notes that mild nausea and vomiting "usually starts around the sixth week of pregnancy and eases up by the 12th week." For some women it persists longer — that is normal too.

Not every symptom clears at once. Pregnancy Info lists fatigue, tender or swollen breasts, frequent urination, mood swings, constipation and headaches among the common symptoms of pregnancy. Some ease as the first trimester ends; others linger into the second.

No two pregnancies feel the same. Pregnancy Info puts it plainly: "Every pregnant woman is different. Some will sail through pregnancy with very few symptoms, and others will be dogged with multiple discomforts." If you still feel rough at 12 weeks, you are not behind — you are simply you.

One symptom is never routine. Pregnancy Info advises taking any vaginal bleeding seriously and to "contact your health care provider as soon as you notice any bleeding." It notes that about one-third of pregnancies have some bleeding before the 20th week, and about half of these continue without further issues — but every episode deserves a call.

What to Do at 12 Weeks Pregnant

NUTRITION AT 12 WEEKS PREGNANT

Keep caffeine below Health Canada’s limit. Health Canada’s Your Guide to a Healthy Pregnancy advises: "Try to keep your caffeine intake below 300 mg a day, which is about two 8-oz (237 mL) cups of coffee." It adds that your daily total should include all sources — coffee, tea, cola and chocolate.
Eat a variety of folate-rich foods. The Public Health Agency of Canada lists corn, oranges, beans and lentils, and dark green vegetables like peas, spinach, broccoli and brussels sprouts as good sources of folate. Foods fortified with folic acid can also be sources of folate, including pasta, cornmeal, and wheat flour. Note that folate-rich foods don’t replace supplements.
Skip the alcohol. Health Canada’s Your Guide to a Healthy Pregnancy states that "there is no known safe amount of alcohol to drink in pregnancy," so the clearest choice is none.
If nausea is still with you, eat little and often. Pregnancy Info suggests eating small meals or snacks often "so your stomach doesn’t get empty," not skipping meals, and sipping fluids to avoid dehydration.

WHAT SUPPLEMENTS TO TAKE AT 12 WEEKS PREGNANT

Keep taking 400 mcg of folic acid daily. The Public Health Agency of Canada recommends "a daily multivitamin with 400 mcg (0.4 mg) of folic acid" for anyone who could become pregnant, continued "throughout your pregnancy and while breastfeeding."
Do not exceed 1 mg of folic acid without advice. The Public Health Agency of Canada is explicit: "You should not increase your dose of folic acid beyond 1 mg per day without talking to your health care provider."
Remember supplements do not replace food. The Public Health Agency of Canada notes that taking a vitamin supplement "does not reduce or replace the importance of a healthy diet," and that dietary folate alone is not enough to protect against neural tube defects.

LIFESTYLE TIPS AT 12 WEEKS PREGNANT

Book or confirm your first-trimester dating ultrasound. Pregnancy Info notes the Society of Obstetricians and Gynaecologists of Canada recommends a "dating" ultrasound at 11–14 weeks — the most accurate way to date a pregnancy, predicting your due date within about 5 days.
Ask your provider about prenatal genetic screening. Pregnancy Info states that "all women should be offered prenatal genetic screening," and that whether you have it is up to you.
Keep moving. Pregnancy Info advises that "pregnant women should accumulate at least 150 minutes of moderate intensity physical activity each week" — walking, swimming and low-impact activity are all good options. Reduce your activity in the event of physical discomfort.
Check any medication with your provider first. Pregnancy Info advises: "Ideally, you should not take any medication during pregnancy unless you and your health care provider determine that it is necessary" — and that goes for natural and herbal products too.

When to Contact Your Doctor or Midwife

Contact your doctor, midwife or other health care provider if you experience any of the following:

Any vaginal bleeding — Pregnancy Info, from the Society of Obstetricians and Gynaecologists of Canada, advises taking it seriously and contacting your health care provider as soon as you notice it, even if it is light.
Bleeding with the passage of clots or tissue, or cramping and pain low in the pelvis or back — Pregnancy Info lists these among the signs of a pregnancy loss and advises speaking to your health care provider.
Signs of infection such as fever — Pregnancy Info says to see your care provider right away.
Nausea or vomiting so severe that you are missing meals, struggling with normal activities, or losing weight — Pregnancy Info says this "is not normal" and your provider can offer other treatments that help.
Severe or one-sided abdominal pain, or pain at the tip of your shoulder with dizziness or faintness — these need urgent assessment; seek emergency medical care immediately.
Any concern that is worrying you — your health care provider is there for exactly this.

Frequently Asked Questions

How big is my baby at 12 weeks pregnant?

At 12 weeks pregnant, your baby is about 6 cm (61 mm) long from crown to rump and weighs around 14 g — about half an ounce — according to Mayo Clinic, roughly the size of a lime. The measurement is crown to rump because the legs are still curled. Fingernails are forming and the face has a more developed profile.

Does morning sickness go away at 12 weeks?

Often it starts to. Pregnancy Info, from the Society of Obstetricians and Gynaecologists of Canada, says mild nausea and vomiting "usually starts around the sixth week of pregnancy and eases up by the 12th week." For some women it lasts longer, and that is still normal. Nausea so severe that you are missing meals or losing weight is not normal — Pregnancy Info advises seeing your health care provider, as other treatments can help.

What is the dating ultrasound at 12 weeks?

It is an early scan used to date your pregnancy. Pregnancy Info notes the Society of Obstetricians and Gynaecologists of Canada recommends a "dating" ultrasound at 11–14 weeks, calculated by measuring your baby’s crown-rump length. It is the most accurate way to date a pregnancy and predicts your due date within about 5 days.

What is prenatal genetic screening in Canada?

It is optional testing offered to estimate the chance of certain conditions, such as Down syndrome and neural tube defects. Pregnancy Info states that "all women should be offered prenatal genetic screening." It can involve a blood test and ultrasound measurements, including nuchal translucency — the fluid at the back of the baby’s neck — or non-invasive prenatal testing (NIPT), a blood test that measures the baby’s DNA in your blood. Screening estimates chance, not diagnosis; a positive result needs further testing.

When does the risk of miscarriage go down?

Most pregnancy loss happens early. Pregnancy Info, from the Society of Obstetricians and Gynaecologists of Canada, explains that "up to one in five pregnancies will end in a loss," and that this "usually" happens "in the first 8 weeks of pregnancy." Reaching the end of the first trimester means the highest-risk window is largely behind you. Pregnancy Info also reassures that even after a loss, "your chance of having a healthy pregnancy in the future is still very good."

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