Can my baby hear before she's born?

Your baby's ears begin to grow when you're about eight weeks pregnant and are completely formed by about 24 weeks. But your baby can start hearing her first sounds -- like your heartbeat or blood whooshing through the umbilical cord -- around 18 weeks, when the bones of the inner ear and the nerve endings from the brain are developed enough. She may even be startled by loud noises!
By week 25, your baby can start to hear your voice and your partner's, and will soon start to recognize them -- so this is a great time to chat your baby up and read to her. Another interesting fact: Research shows that a baby's heart rate often slows down when her mom is speaking, a sign that she not only hears and recognizes the sound, but is calmed by it. Your voices will sound a bit muffled to your baby -- about as well as you hear under water -- because the ears are still covered with vernix, the thick, sticky coating that protects the skin from becoming chapped by the amniotic fluid.
You may notice your baby's movements change in response to sounds -- like a sudden kick after a door slams, for example. In fact, some doctors suggest getting your baby accustomed to sounds she's likely to hear as a newborn (like the vacuum cleaner or dishwasher) now, so they won't be as likely to wake her up or make her cry once she's born. --Karin A. Bilich