The fetus continues to develop before birth. It begins to grow ratty deposits under the skin, and it gains weight. The fetus reaches the age of viability, the point at which it can survive if born prematurely at about prenatal age 22 weeks, although through advances in medical technology this crucial age is getting earlier. At prenatal age 28 weeks, the fetus weighs less than 3 pounds and is about 16 inches long. It may be capable of learning: One study found that the infants of mothers who had repeatedly read aloud the Dr. Seuss story The Cat in the Hat before the infants’ birth preferred the sound of that particular story to other stories after they were born.