12 Weeks Pregnant: Your Baby’s Development

At 12 weeks pregnant, you’ve nearly reached the end of the first trimester, and your little one has been busy. All of your baby’s vital organs and body parts will be in place this week; even the sex organs have developed.

It’s still too early to determine the gender of your baby, but your healthcare provider will likely be able to let you know (if you choose to find out before birth) during a mid-pregnancy ultrasound scan in the second trimester. In the meantime, you can enjoy playing around with our Guess Your Baby’s Gender quiz.

Your baby’s heartbeat is probably audible with an external Doppler device by now, so you may get the opportunity to hear it if you have a checkup this week. At this time, your baby has fully formed eyelids. These aren’t just closed tightly; they’re actually fused together and will remain that way until late in your second trimester.

At this point, your baby's hands are a little more developed than the feet, and the arms are longer than the legs. The little nailbeds that recently developed are starting to sprout fingernails and toenails, which will continue to grow to the tips of the fingers and toes during the next trimester.

Your baby is also starting to move a little, but it’s still too early for you to feel these movements. During the coming weeks, your baby’s organs and muscles will continue to develop and your baby will continue to grow bigger.

The Size of the Fetus at 12 Weeks Pregnant

At 12 weeks, the fetus is about the size of a passion fruit, measuring close to 2.5 inches (6.3 centimetres), crown to rump, and weighing approximately 0.5 ounces (14 grams).

Take a look at the illustration below to get a visual idea of how your baby is developing:

fetus at 12 weeks pregnant


Mom's Body at 12 Weeks Pregnant

Feed me! As the nausea and discomfort of early pregnancy start to subside, you may find that you’re getting your appetite back. Be sure you're eating enough and maintaining a healthy diet, but don't feel you actually need to eat for two.

Experts recommend adding only about 300 extra calories a day, on average, during pregnancy. Your healthcare provider will be able to give you personalized advice about what’s right for you.

You might like to use our Pregnancy Weight Gain Calculator to get an idea of what a healthy weight gain looks like based on your pre-pregnancy weight.

You might be looking at your belly and wondering if it’s the right size for 12 weeks pregnant. Try not to compare your bump to other moms-to-be. Every pregnancy is unique and it will depend on many factors like your build, whether you’re pregnant with twins, your pre-pregnancy weight, and whether this is your first baby.

In other words, at 12 weeks pregnant, you may be starting to see a more prominent belly, but if not, don’t worry, it will appear before you know it.

12 Weeks Pregnant: Your Symptoms

At 12 weeks pregnant, here are some of the symptoms you may be experiencing:

  • Bleeding and sensitive gums. As your blood volume increases and hormone levels change, you may find your gums start to swell and are more sensitive; they may even bleed when you brush or floss. Although this may be disconcerting, it can be completely normal. Continue to brush and floss regularly, and speak to your dentist, if needed, to check that everything is OK. Using a softer toothbrush and rinsing with salt water (a teaspoon of salt dissolved into a cup of warm water) can be helpful.

  • Feeling lightheaded. During pregnancy, your body produces more blood vessels, and your hormone levels change. This can leave you feeling dizzy or lightheaded from time to time. Wearing loose clothing, keeping hydrated, avoiding long periods of standing, and remembering to eat regularly can help you feel better. Also, try to stand up slowly after sitting and avoid changing positions abruptly. Be sure to call your healthcare provider if you also have abdominal pain or vaginal bleeding, or if your feelings of lightheadedness persist.

  • Sensitivity to smells. Your sense of smell can be particularly sensitive during this phase of pregnancy. If certain odours bother you, try eating cold or room-temperature food to avoid strong odours, using a fan when cooking, and having someone else in your household take out the trash.

  • Bloating. Hormonal changes and your growing uterus might leave you feeling bloated. Eating slowly helps prevent you from swallowing air, and this may help relieve some of the bloating.

  • Spotting or bleeding. At 12 weeks pregnant, or anytime during pregnancy, if you notice bleeding other than light spotting (which can occur after sex, for example), especially if accompanied by cramping, it’s a good idea to contact your healthcare provider to get your symptoms checked.

12 Weeks Pregnant: Things to Consider

  • Be sure to follow a balanced pregnancy diet that includes proteins like meat, chicken, fish, or plant-based substitutes. You’ll want to include a wide variety of vegetables and fruits each day for the vitamins and minerals they contain, plus calcium-rich foods like low-fat dairy, beans, nuts, and tofu.

  • Start doing Kegels, if you haven’t already. Kegel exercises help strengthen the pelvic floor muscles that support your uterus and bladder. There are many benefits, including helping to prevent accidental urination during and after your pregnancy. Kegels are easy to do: You simply squeeze your pelvic floor muscles by contracting those muscles you’d clench if you were trying to stop the flow of urine or stop yourself from passing gas. Hold for a few seconds, and then release. You should aim for at least 3 sets of 20 each day. You can increase how many Kegels you do and how long you hold them for as your muscles grow stronger. Consult our guide to learn more about Kegel exercises.

  • Start a pregnancy journal. You might want to write down all of your exciting pregnancy milestones so you can look back on your journey after your baby is born. Consider taking weekly photos of your developing bump after it begins to show. Once you have an ultrasound scan, you could even add a print copy to the journal. There are many styles of pregnancy journals you can buy online or from a local retailer, or you can create your own keepsake in the form of a scrapbook or a traditional diary.

  • Have you started thinking about baby names yet? Try our Baby Name Generator, which will help you find a name you’ll love.

  • If you’re a working mom-to-be, you might be thinking of announcing your pregnancy to colleagues early in the second trimester. Check out our tips on how to announce your pregnancy to coworkers.

  • Take stock of what’s to come. As you head toward the second trimester, find out what you need to know about this next stage of pregnancy in our handy, go-to pregnancy guide. And, if you’re wondering how many months along you are at 12 weeks pregnant, it’s likely you’re at the tail end of month three.

12 Weeks Pregnant: Ask Your Doctor

  • When and where will flu shots be available? Experts recommend all moms-to-be get the vaccine as soon as it comes out, which is usually a month or two before “flu season” begins. Flu season runs from October to May.

  • When is it OK to share the news with friends and colleagues?

  • Is it possible to avoid getting stretch marks?

  • What genetic screening testing is recommended, and why?

12 Weeks Pregnant: Your Checklist

  • Start to plan when you will tell your employer about your pregnancy.

  • Plan how you will reveal your big news to family and friends. You could organize a fun pregnancy announcement party, or you could give those closest to you a special pregnancy announcement card. No matter how you do it, you and your loved ones will cherish this special moment.

  • Schedule a dental checkup.

  • Research local prenatal or birthing classes — your healthcare provider may be able to point you in the right direction. Find out when they start and when you need to sign up.

  • Sign up for even more weekly pregnancy tips:

How we wrote this article
The information in this article is based on the expert advice found in trusted medical and government sources, such as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.