Pregnancy is a time of rapid change for both you and your growing baby. Fetal development begins at the time of conception and progresses until the time of birth. As your baby gets ready for life outside your uterus, he develops a sense of hearing, allowing him to listen to your heartbeat and other sounds.
Fetal Development
Normal pregnancies last about 40 weeks, starting with the first day of your last menstrual period. Your doctor may refer to the course of your pregnancy in trimesters that each lasts about 13 weeks. Your baby’s sense of hearing begins to develop during the second trimester and your baby can hear between weeks 17 and 19 of gestation, according to MedlinePlus.
Sense of Hearing
Around week 18 of your pregnancy, your baby’s outer ears begin to develop on the sides of his head. As the baby’s outer ears form, his auditory nerves also develop, allowing him to hear sounds. Your baby may weigh around 7 ounces and measure approximately 5.5 inches in length at the time he begins hearing sounds.
Sounds
The amniotic fluid surrounding your baby, as well as your organs, muscles, fat and skin, help to muffle and soften the sounds that reach your baby from the outside world. The sounds your body makes, such as your heartbeat, blood flow and digestive processes provide continual accompaniment for your growing baby.
Responses
During your pregnancy, you may notice that your baby responds to low-frequency sounds earlier than she responds to higher frequencies. Very loud noises may startle her, causing her to lurch or move suddenly in utero.
Warning
Drinking alcohol during pregnancy can result in fetal alcohol spectrum disorders, a group of conditions that includes various physical and behavioral problems. The U.S. Centers for Disease Control and Prevention warns that a person with fetal alcohol spectrum disorders may experience hearing problems.
