The fourth month (weeks 13 through 16)

At the beginning of the second trimester, the baby’s facial muscles begin to work out. It learns to make various facial expressions, chew, and suck its thumb. By this time, the baby looks more and more like a little person. It already has hair, eyebrows, and eyelashes. During week 13, fine lines begin to form on the fingers of the fetus, which will later become fingerprints. A little later, thin translucent fingernails and toenails will also appear.

The active development of the body begins. The neck becomes more distinct, separating the head from the torso. The arms become proportional to the rest of the body and the legs develop. Over the next few weeks, the fetus will double its weight and gain a few inches in length. The baby’s heart is now pumping about 25 quarts of blood each day, and this amount will continue to increase as the baby develops.

By week 13, the baby begins to produce meconium, which the mother will find in the first diapers after birth.

During week 15, the fetus begins to develop taste buds, which will be fully formed by week 20.

During week 13, the fetus is the size of a pea pod, during week 14, it’s the size of a lemon. During week 15, the baby reaches the size of an apple, and during week 16, its size is comparable to an avocado.

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