Between weeks 24 and 28, your baby will be at their most active. Unfortunately, this activity often ramps up just as you're trying to sleep! The baby's iris (the colored part of the eye) doesn't yet have pigment, but the eye itself is well-developed. The lungs are beginning to produce surfactant, a detergent-like substance that will help the lungs expand and function after birth. Your baby's skin is still thin and translucent, allowing you to see blood vessels, bones, and organs beneath it. It will thicken as the months pass. Even though their eyes are closed, all the parts of the eyes are present, including the retina. The iris, the colored part, still doesn't have any pigmentation. The baby's crown-to-rump length is 21 cm (8.3 inches), and they weigh about 500-600 grams (1.1-1.3 pounds). They have developed a hand grip reflex and a startle reflex. As the baby gets bigger, they have less space to move around, so the movements you feel might change from big kicks to more rolling and stretching.