By approximately the 23rd week of gestation, babies are able to hear noise in the womb. They can hear the sounds of their mother’s body functioning, such as the heart and digestive system. Though the sound is muffled by amniotic fluid, babies can also hear outside noise. Usually a fetus will begin to recognize certain noises and respond to them. Learning new sounds and becoming accustomed to them can be an important part of in utero development.
Everything a baby hears in the womb will be combined with the continuous internal sounds of the mother’s body. For this reason, the sound of a beating heart can be soothing to babies once they are born. The same can be said of white noise, as the rush of blood and other fluids through the body provide a similar sound.
A pregnant woman may feel her baby react to outside noise in the womb. Familiar voices, such as those of the father or siblings, may cause the fetus to move around. It can be beneficial for family members and other close friends and care providers to speak gently to the baby and essentially introduce themselves to the unborn child. There may also be certain sounds or kinds of music that cause the baby to react. While an unborn child may not be able to pick up exact pitch from within the protective layers of the mother’s body, many infants do recognize familiar voices once they are born — particularly those of their mothers.
Though doctors often advise that an expectant mother remain calm, there is no need to completely restrain strong emotions such as anger, fear, and sadness so that the baby can be protected from this kind of noise in the womb. It is generally best for the health of the child to manage overall stress and anxiety, but it is nevertheless healthy to express a range of emotions. This kind of variety in sound can even help baby to adapt more quickly to the outside world.
Though it is clear that unborn babies respond to sound, there has historically been no evidence that noise in the womb can harm a baby’s hearing. If the baby becomes particularly active due to a loud external noise, it may be advisable to move to a quieter area. It can often be best for a pregnant woman to avoid loud situations for the sake of her own stress level and well-being, in addition to that of the baby.