12 Weeks Pregnant: Baby Size, Symptoms and What to Do

Your baby this week

Your baby's organs and muscles are in place and now mainly need to grow and mature. The soft skeleton is gradually hardening into bone, and the sex organs have formed.

Week 12 is a milestone for many: the risk of miscarriage drops considerably by the end of the first trimester, so it's a common time to share the news. Your uterus is rising above your pubic bone, and your provider may be able to feel it from the outside. Your baby's reflexes are developing; if something touches the palm, the fingers curl. More of the cartilage skeleton is turning into bone. If nausea is fading, you may feel your energy coming back. Weight gain in the first trimester is usually small, a few pounds, and if you've been sick you may even have lost some, which isn't unusual. The recommended total gain depends on your pre-pregnancy BMI; the weight gain calculator shows your range week by week.

By the numbers

Week 12 covers days 84 to 90 counted from the first day of your last period, which is 30% of a 40-week pregnancy. About 196 days remain until a 40-week due date. Since last week, an average baby gains about 0.5 oz (13 g). By date of conception, your baby is about 10 weeks old.

Pregnancy is dated from the first day of your last period, so conception happens around week 2. Your due date is 280 days (40 weeks) from that day, and an early ultrasound may adjust it.

Your body

For many people, nausea and fatigue start to ease over the next few weeks. Call your provider about any vaginal bleeding.

Tests and to-dos this week

The first-trimester screen window closes at the end of week 13, so check that it's scheduled if you want it. Keep taking your prenatal vitamin.

• First-trimester labs · weeks 6–13 · test

  Blood type and Rh factor, antibody screen, blood count, and infection screening including syphilis (ACOG recommends syphilis testing at the first visit, in the third trimester and at delivery).

• First-trimester screening (blood test + NT ultrasound) · weeks 10–13 · test

  Optional genetic screening, usually done together between 10 and 13 weeks.

Coming up: Quad screen (optional) (from week 15). Full prenatal visit schedule

Tips for the first trimester

• Take 400 micrograms of folic acid a day; your provider may advise a higher dose if neural tube defects run in your family.
• Avoid alcohol, smoking, raw or undercooked meat, fish and eggs, and unpasteurized dairy.
• For nausea, try small, frequent meals and sipping fluids; call your provider if you can't keep anything down.
• Check every medicine and supplement you take with your provider or pharmacist before continuing.

Last week and next week

Last week (11): Fingers and toes have separated, and tiny nails are starting to grow.

Next week (13): Ovaries or testes have developed.

Frequently asked questions