12 Week Ultrasound

At the 12th week of your pregnancy, the baby starts forms into a baby and you will have the full view of it maybe for the first time. All of his/her organs started to work. His/her shape is more like human and you can recognize all the parts on his/her face. But, there are more reasons for 12-week ultrasound. They are related to pathological conditions which your doctor can’t see using ultrasound only. Therefore, he will suggest you The Screening Test.

What Happens at 12 Weeks of Pregnancy?


Your baby has more than doubled in size during the past three weeks. He/she is about 5-6 cm from head to bottom (CRL) and weighs up to 14 g. Cartilages are the places where the bones will be, but they are now beginning with the hardening process which takes a long time. Most of your baby’s systems are fully formed. Your baby is starting to look more human every day. His/her eyes are closer together and his/her earlobes are taking shape.

The Reflexes

The most dramatic development this week is the development of the reflexes. They are becoming faster and more sensitive. Your baby will wriggle a little if you gently prod your belly. Your baby’s fingers will soon begin to open and close, and he/she is gaining some of the skills it will need after it’s born. He can close his fingers to make a fist and put it in his mouth to suck. His/her toes will curl, and his/her eye muscles will clench. At this time, he/she will have developed the startle reflex called the Moro reflex. This reflex happens when the baby hears the sound and reacts to it by opening and closing his/her arms and legs.

Although your baby progresses with his/her movements, you won’t be able to feel it yet. But, you can see it on the screen of the ultrasound apparatus.

Digestive System

The other important change is the baby’s digestive system has moved into place in his/her abdomen, and it begins to flex its muscles. His/her intestines have grown so fast as well as his/her kidneys which begin with the excretion of the urine into his bladder.

Nervous System

Meanwhile, nerve cells in his/her brain are multiplying rapidly, and synapses are forming faster each day.  The pituitary gland at the base of the brain has started producing hormones. The immune system starts to work with the production of the white blood cells inside the bone marrow.

Reasons for 12 Weeks Pregnant Ultrasound Scan

There are many reasons for your doctor suggesting to have the 12-week ultrasound scan. One of the most common ones is the screening for one of the congenital chromosomal abnormalities called Down Syndrome or Trisomy 21. This implies that there is an extra chromosome in every cell of the baby’s body. Therefore, we measure baby’s skull, actually, the Biparietal distance. It is measured from the beginning of the fetal skull to the inside aspect of the distal fetal skull. If the fetal BPD is below the 10th percentile, the baby has symmetrical growth retardation.  The femur length can be used as a marker for fetal malformation and genetic abnormality. In many cases, as we can see in Trisomy 21, fetuses have shortened femurs. The measurement of a fluid at the back of the baby’s neck by ultrasound called the Nuchal Translucency allows your doctor risk assessment of Down Syndrome, as well.


Your doctor can see as well:

  • The uterus, fallopian tubes and pelvic region,
  • Number of fetuses and their position within the uterus,
  • The fetal heartbeat,
  • Location and size of the placenta,
  • Size of the baby,
  • Volume of the amniotic fluid,
  • Determination of the gestational age,
  • Possible anatomic abnormalities of the baby,
  • Estimate the date of the delivery.

How Will Your 12 Weeks Pregnant Ultrasound Be Done?

The 12th-week ultrasound is usually done via the mother’s abdomen. But the doctor might offer a vaginal scan as well. The sonographer will advise drinking 2 glasses of water an hour before the trans-abdominal ultrasound for a clearer vision of the fetus. This will push your uterus up and make a clear view of your baby.

During the trans-abdominal examination, you will lie down and the sonographer will put some gel on top of your stomach, therefore the apparatus will slide easier over the abdomen. The only discomfort you may feel may be the pressure on your full bladder.

If you are overweight or if your womb is sitting very deep inside your pelvis, the sonographer might suggest a trans-vaginal ultrasound to get the clearer image since the transducer will be closer to your baby. The sonographer will be able to talk with you throughout the procedure and explain what you can see during the ultrasound.

What Happens If a Problem Is Found At the 12-Week Scan?

Besides the basic ultrasound, at the 12th week, it is recommended to get the Screening Test for the first trimester of pregnancy. It means measuring of the fluid at the base of the baby’s neck, called the Nuchal Translucency. PAPP-A (pregnancy-associated plasma protein-A blood test) and Beta hCG (human chorionic gonadotropin blood test). The Screening Test provides better information about the risks of some malformations such as Down Syndrome, so if there are concerns, further testing can be done.

Chorion Villus Sampling test and an amniocentesis are additional testings that can provide great information about the fetus health.


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