12 weeks – Your tiny baby is structurally completely developed.


Your baby now measures around 5 cm from crown to rump, and may weigh around 15-20 grams.

It’s all organs have been developed and would just grow in size from now on. Now you may also feel relief from your nausea and vomiting. The nature had mediated these symptoms to you through hormones, as it wanted to avoid accidental ingestion of any harmful substance that could adversely affect the baby.

The face now looks more human; however the size of the head is still more than rest of the body. It is because, the baby’s development and acquisition of functions happens gradually from top to bottom and from center to periphery.

With the maturation of nervous system, the baby develops basic reflexes. These reflexes are involuntary movements that would protect the baby from inadvertent injury and help them grow in newborn period.

Your baby can stretch, yawn, move head side-wards and do all sorts of complex movements with opening and closing the fist.

The fetus is active doing summersault, however you still won’t be able to perceive the movements until 20 weeks of pregnancy.

The baby can swallow amniotic fluid, which in combination with bile produced from liver is stored in the intestines in the form of thick meconium (dark green colored intestinal content).

The baby’s kidneys have begun to function and the amniotic fluid is now largely formed from the baby’s urine.

This week is very important, as your uterus protrudes above waist line and become abdominal organ, you would be able to feel it and your doctor would be able to make you hear the heart sounds easily with the help of fetoscope.

It is advisable to undergo two most important non-invasive screening investigations to rule out major chromosomal/ structural developmental abnormalities. These are recommended  between 11 weeks to 13+6 weeks, when your baby’s CRL is 45 to 84 mm.

1- First trimester Nuchal Transluscency Scan-

During this ultrasonography, in addition to fetal growth and basic parameters, special focus is given on-

  • Nuchal transluscency – Thickness of the area at the back of baby’s neck.
  • Development of nasal bone.
  • Blood flow through the Ductus Venosus ( A major vessel that bypass the liver and shunts the oxygenated blood directly into the inferior vena cava of fetus).
  • Blood flow through Tricuspid valve, through which blood flows from Right atrium to Right ventricle.

2- Double marker test-

These tests measures the amount of two substances in mother’s blood.

  • Beta HCG.
  • Pregnancy Associated Plasma Protein A (PAPP-A).

The abnormal blood levels of these two substances may indicate certain birth defects.

Based on the reports of screening tests, your doctor may refer you to the Maternal Fetal medicine Specialist for further confirmatory invasive tests.

Relax, as the medical specialists are there to help you and not to stress you. So, don’t fail to check with your Doctor.