Baby’s First Heartbeat at 12 Weeks Pregnant


When you are 12 weeks pregnant, your baby is now similar to the size of a lime fruit, measuring more than 2 inches in crown-to-rump length and weighs half an ounce. Right now, your baby’s significant development is on his body reflexes and is growing more than doubled in size. Being 12 weeks pregnant is also remarkable for you as you are now on the last week of your first trimester and can now hear your baby’s first heartbeat!

Your Baby’s Development this Week

External changes

12 weeks pregnant

Your baby will be able to open and close his fingers (fist-like) soon, curling his toes, clench eye muscle as well as making sucking movements. The intestines, which are developing rapidly, are protruding into the umbilical cord. They now have room to move into the abdomen area. 

The muscles on his digestive system are also starting to flex and is beginning to perform contraction movements, which gives the ability for your baby to digest food on the digestive tract.

His facial features are starting to look more human now. His eyebrows and lips already forming while his eyes are making movements and his ears are now in place. Inside his mouth, his salivary glands are beginning to works as well.

If you can see through the inside of your womb, there is now a change on his body proportions: he is now less in curling position and more upright. Your baby’s head is growing slowly, giving way for his body’s growth. His arms and legs are also growing long. Your baby can feel when you put your hand on your tummy, but still you will not be able to feel your baby’s movements.

Internal changes

The body organs are also now operational and are working multiple tasks.

Your baby’s liver is also starting to produce bile and the kidneys are already functional as well as it is now producing urine into his bladder.

On the other hand, on your baby’s reflex development, the nerve cells are multiplying while synapses are also forming in his brain, which is now responding from his brain’s controls. However, it is not yet fully operational.

This is also the week when your baby’s vocal cords are beginning to form. His nails on 10 fingers and toes can now be seen. Your 12th week of pregnancy is memorable for you as you will now be able to hear your baby’s heart beat for the first time! You will now be able to hear the heartbeat with an external Fetal Doppler.

Other developments during this week includes lungs continuing to mature, the amniotic fluid being inhaled and exhaled, spleen and liver discards old red blood cells and produce antibodies, your baby’s genital is completely visible now, and your baby’s sweat glands are developing while the body hair is growing as well. The bone marrow is also now capable to produce white blood cells while his pituitary gland can now also release hormones.

Your Body Changes at 12 Weeks Pregnant

With so many rapid developments happening to your baby, pregnancy hormones are also making changes on your body to adjust, accommodating the little tenant inside your womb. Constipation is more common this week as your muscles on your stomach slows down, making your stools harder and drier as well. While your baby is growing each week, you uterus also expands and is now pushing into your abdomen. This also means that you will have fewer urge to urinate. However, soon you will feel uncomfortable about it. Your blood is also increasing causing your heart rate to speed up.

You will also notice that you have wider hips due to your uterus expanding and is now becoming about the size of a large grape fruit. Because of the rise in progesterone and estrogen, you may experience some unpleasant pregnancy symptoms like morning sickness and mood swings, but hope that you are used to it by now.

Other early pregnancy symptoms you will continue on experiencing are nausea, tender breasts and nipples, food aversions and fatigue, and additional to those symptoms is dizziness. Pregnancy hormone progesterone is your culprit here. The said hormone is causing your blood vessels to relax when you are around 12 weeks pregnant, therefore increasing the flow of blood to your baby. It is beneficial to your baby though. However, for you, it slows the flow of the blood to your brain and lowers the blood pressure causing dizziness as well as lightheadedness. Dizziness is also caused by your low blood sugar level especially if you are not eating well.

What to Think and Do this Week

Continue eating healthy prenatal foods though, some of your pregnancy symptoms are easing already. If it is becoming worse, let your health care provider know. Remember that during pregnancy, there are many possible risks that could harm you and your baby. Some of these symptoms such as bleeding and spotting could be symptoms of molar pregnancy, which is a cyst in the uterus. It is due to abnormal development of placenta and could cause miscarriage. You should also be aware of the risks of urinary tract infection at this stage (usually 6 to week 24).

Pregnant women are also on a great risk of flu which is why it is important to get vaccinated. Of course, before you get a shot of the vaccine, make sure you let your health care provider know. As your uterus grows, your midwife can now feel the top of your uterus, or the fundus, low in your belly. You may now need to wear your maternity dress to give room to your growing womb.

You may also feel that your morning sickness is almost gone or just easing, and that your appetite is finally back. Eat healthy prenatal foods to help your child grow healthy. See your midwife or GP for your antenatal appointments. Make sure that you have asked all the questions you wanted to know concerning about being 12 weeks pregnant.

This week is also the right time to let your friends, relatives or co-workers (including your boss) know regarding your pregnancy. Though, you may just keep it a secret until your baby bump is obviously noticeable!


Editor in Babiology, mother of two, highly passionate about sharing the pregnancy care and post delivery care learning with the readers.

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