The fetus is now about an inch long (approximately 2.3 cm or 0.9 inches) and weighs about 2 grams (0.07 ounces). Significant progress is happening this week. The legs have lengthened, and the arms are bending at the elbows. Toes are sprouting, and fingers and thumbs are clearly differentiated. The structures inside the abdomen that will become the liver, gallbladder, spleen, and adrenal gland are becoming specialized, each taking on its unique function. The fetus is moving vigorously in response to light and noise, although you won't be able to feel these movements yet. These movements would be visible on an ultrasound. Eyelids are beginning to form and grow over the eyes, protecting them as they continue to develop. The placenta has now fully taken over the production of all the hormones necessary for the uterus to sustain and nurture the developing baby. The optic nerve and eyelids are developing, and the external ears are also forming. The baby's crown-to-rump length is about 12 mm (0.5 inches). The baby weighs about 1 gram. The legs have lengthened, and the toe buds have started to sprout. The arms have grown and begun to bend at the elbow.