Fetal development: Week by week Guide: Month 3

Fetal development: Week by week Guide: Month 3

20 Apr 2022 | 3 min Read


Author | 2574 Articles

In pregnancy, mothers want to know everything. What is happening to them, to their baby, growth patterns, what to expect, etc. To keep ourselves updated, we refer to endless articles and books so as to find out what to expect, when expecting. Your doctor will tell you a lot of things, including fetal changes that happen inside the amniotic sac.

At times, however, your doctor might forget to fill you in on such scrupulous details. At such times, reading numerous biology books might not be humanly possible. Therefore we bring to you the fetal development guide (week by week) for the third month (end of the first trimester).

First week

The embryo grows to about 30mm in length and fingers and toes are well defined. Cartilage and bones begin to form and develop. Upper lip, tongue, nose tip and the larynx begin to develop. Eyelids also develop although they remain closed for several months so as to allow the eyes to develop. A major part of the construction of the heart is complete.

During this week of pregnancy, the baby swims around in the amniotic fluid and has lengthening arms and legs. Finger and toes although forming, are still in webs of skin. These babies can flex their elbows and wrists and also move around gracefully. The head appears much longer than the rest of the body because the brain is growing very rapidly. Ears, teeth and the mouth palate are also in the process of formation.

Second week

The embryo is now technically a fetus. The fetus is the size of a strawberry with 2mm long feet. Neck, nipples and hair follicle begin to form. Body muscles, jaws, mouth cavity, ears and nose are almost completely developed. Fingerprints start becoming more distinct.

In this week, the fetuses are on the verge of forming testicles or ovaries. Each week, as the fetus grows, the mother’s waistline thickens and gradually curves outwards.

Third week

Multiplication of neurons takes place. The fingers and toes have completely separated. Taste buds and tooth buds are developing so as to lay a foundation for 20 milk teeth. If it is a male, testicles start producing testosterone hormone. The baby has an upper lip and the cartilage is calcifying into bones.

Eyelids have fused shut and genitals have begun to form.

The brain grows rapidly and produces more than 250,000 nerve cells in a minute. Wrists and ankles have formed. The baby is now the size of a small plum.

Fourth week

By the end of the third month, the baby is almost completely formed. The fetus moves spontaneously in the amniotic sac and the face of the baby becomes distinct. Babies may suck their thumbs and get hiccups, their pancreas is functioning and producing insulin. Feet are almost half an inch in length and heartbeats may be audible. The baby now has a chin, nose and a proper facial profile.

The brain is fully formed and hence the baby can feel physical pain. Hair and soft fingernails start developing. The kidneys are fully developed and begin to secrete urine. The fetus at this stage is extremely active and the mother can feel the movements happening inside. The baby is prone to kick a lot during this week since the feet are almost completely developed.



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