The 2nd trimester of pregnancy, marks the period when the baby is strong enough and ready to grow. The tissue and body function will experience significant growth. At week 13, for example, the baby's body length ranges from 65-79 mm, with a weight of 20 grams. In this week, the organs of the nose, mouth, and skin begin to adjust with time. The neck begins to grow perfectly to support the baby's head. Previously, the baby's head was supported by his shoulders. These neck muscles replace the function of the baby's shoulders as a supporting head.