Baby’s Growth Journey – A pregnant mother is always curious about how big the developing baby is, what the baby looks like as it grows inside her, and when she would feel it move.

Let us take a peek inside the womb to see how a baby develops from month to month. Baby’s growth at each stage can be checked with ultrasound scan

First month – Fertilisation of egg

After the egg has been fertilized by the sperm, it starts to divide into more cells. This happens all the time it is carried along the fallopian tube to the uterus.

By the time it reaches the uterus the fertilized egg has become a cluster of cells which float in the uterine cavity until it embeds in the wall of the uterus.

Fertilization Of Egg and Sperm

This implantation in the wall of the uterus is when conception is complete. This is roughly 4 weeks after day one of the last menstrual periods if a mother has a 28-day cycle.

Second month

At 5 weeks the embryo is the size of a grain of rice (about 2 mm long) and would be visible to the naked eye. It has the beginnings of a brain with 2 lobes and its spinal cord is starting to form.

At this stage, early pregnancy scan is performed to confirm the development of the embryonic sac and the presence of fetal hearbeat

At 6 weeks of ‘pregnancy’ (3-4 weeks after fertilisation) the embryo has a head with simple eyes and ears.

Its heart has 2 chambers and is beating. Small buds are present that will form arms and legs later. The beginnings of the spine can be seen and the lower part of the body looks like a tail.

At 7 weeks, the limb buds have grown into arms and legs. Nostrils can be seen on the embryo’s face. The heart now has 4 chambers.

At 8 weeks, the eyes and ears are growing, and the baby is about 2 cm long from crown to rump.

The head is out of proportion with the body and the face is developing. The brain and the blood vessels in the head can be seen through the thin skin.

The bones in the arms and legs start to harden and elbows and knees become apparent. Fingers and toes can also be seen.

Third month

What is known as the embryonic period finishes at the end of week 8 and the fetal period begins. This period sees rapid growth of the fetus, and the further development of the organs and tissues that were formed in the embryonic period.

At week 9 the head is almost half the crown to rump length of the fetus.

Then the body grows substantially in length until by week 12, the head is more in proportion.

By the time a mother is 12 weeks pregnant, her baby is just over 5 cm long from crown to rump. Its body is fully formed, including ears, toes and fingers complete with fingernails.

The external genitals appeared in week 9, and now, by week 12, have fully differentiated into male or female genitals. By week 12 the eyes have moved to the front of the face and the eyelids remain closed together.

 NT scan will be performed at this stage to eliminate the possibility of down syndrome in babies.


At the end of the third month, your baby is about 7.6 -10 cm (3-4 inches) long and weighs about 28g. Since your baby’s most critical development has taken place, your chance of miscarriage drops considerably after three months into the pregnancy.

Check here to know about the development of the baby in second and third trimester

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