1. Lung Development: Fetal lungs undergo significant development and structural maturation in preparation for postnatal breathing. The lungs start as simple buds and gradually develop intricate branching structures called bronchial trees, which form the airways. The growth and branching of the airways create an extensive surface area necessary for gas exchange after birth.
2. Fluid-Filled Lungs: Fetal lungs are filled with fluid, not air, during gestation. This fluid-filled environment is essential for lung development and protects the delicate lung tissues from compression. The fluid also helps in the formation and expansion of airways and alveoli.
3. Production of Surfactant: Fetal lungs produce surfactant, a substance that reduces surface tension at the air-liquid interface of the alveoli. Surfactant is crucial for preventing alveolar collapse after birth and ensuring proper lung function.
4. Cardiovascular Function: Fetal lung development is closely linked to cardiovascular development. The rhythmic movements of the diaphragm associated with lung development contribute to the development and strengthening of the heart muscles.
5. Preparation for Breathing: In late pregnancy, the fetus starts making respiratory movements, also known as fetal breathing movements or fetal respiratory movements. Although these movements do not involve gas exchange, they help strengthen the respiratory muscles and coordinate the neural pathways necessary for postnatal breathing.
6. Adaptation to Extrauterine Life: Towards the end of gestation, the lungs undergo changes in preparation for the switch to air breathing after birth. The fluid-filled lungs gradually absorb the fluid, and the airways become air-filled. This transition occurs during the first few breaths taken by the newborn.
It's worth noting that the full maturation of the lungs continues after birth, especially during the first few years of life. The structural and functional development of the lungs is a gradual process that occurs both in utero and postnatally.