Can Noise Affect The Foetus Or The Newborn?

Many women work in noisy surroundings, such as working with machines, loud music, crowds of people, guns, trucks, sirens or airplanes. Working in a noisy surrounding, especially, when you are pregnant, can affect your hearing and stress levels and may also increase your probability of having a baby with hearing problems. Furthermore, it is not only during your pregnancy that you should avoid exposure to excessive noise, even after delivery, high noise levels may cause harm to the newborn.

Here's more information on how much noise is considered safe during pregnancy, its impact on the foetus and the newborn, and what you could do to reduce your noise exposure for a healthier pregnancy.

How Much Noise Is Considered Safe During Pregnancy And For A Newborn?

According to experts, prolonged and repeated loud noise exposure, such as those from an industrial workplace, for more than seven hours a day, is what needs to be attended to. The National Institute for Occupational Safety and Health suggests that pregnant women should avoid regular noise exposure that is louder than 115 decibels (like that of a chainsaw for example).

Also, frequent brief exposure to extremely intense sound at 150 decibels or more (like that of a screaming jet engine) may cause similar problems for the foetus or in a newborn.

When Does The Hearing Develop In Babies?

At about 24 weeks, your baby's outer, middle or inner ear, including the cochlea (snail-shell shaped tube) in the inner ear where vibrations are converted into nerve impulses begins to perceive sounds. They are well-developed, and the baby's ear is mature enough to hear sounds, and he may turn his head in response to voices or noises.

But when inside your uterus, the noises are muffled due to the presence of a physical barrier (amniotic fluid) and your own body. When within this fluid-filled home, the baby's eardrum and middle ear cannot do their normal job of amplifying sounds.

So the actual loud noises may not seem as loud to your unborn. But that is true only as long as the noises are not too high and they do not last too long. Chronic noise exposure can invoke stress response in humans and may lead to a permanent hearing loss.

How Do Increased Noise Levels Impact The Foetus?

Although high noise level is not the only reason for hearing problems in babies, if you work in a noisy job, it may impact your developing baby in the following ways:

- Increased noise levels may lead to stress, which can cause significant changes in your body when pregnant, affecting the development of your baby.

- Sound travels through your body (over the abdominal wall and uterus) to reach your baby. Although this sound would be muffled in the womb, very loud noises may still damage your baby's hearing. The noise stimulates the inner ear through soft tissues and may potentially affect the hearing of the foetus by damaging the hair cells within the cochlea.

- Regular exposure to high noise levels increases the odds of a baby having to suffer from hearing loss, particularly at higher frequencies. Repeated exposure to loud noise may also increase the risk of premature delivery and low-birth-weight babies.

- The use of earplugs may protect your hearing, but, if you are pregnant, then the only way to protect your baby's hearing is to keep away from loud noise as much as possible.

Impact Of Noise On The Newborn

The inner ear (cochlea) contains tiny cells that are sensitive to sound. These cells convert sound vibration into messages to the brain. On prolonged exposure to loud noise, physical changes occur in various parts of the inner ear.

If it's a short-term noise exposure, these cells may recover, but long-term exposure to noise can cause permanent damage. Because of their comparatively thin skulls, babies are at a higher risk from loud sound in comparison to adults.

Precautions To Protect Your Foetus And Newborn From Loud Noise

- Use hearing protection (earplugs) to protect your own hearing if you are exposed to loud noise. Although your hearing may not protect your developing baby from loud noise, excess noise can result in stress, causing changes in your body that affect your developing baby.

- If your working environment has high noise levels, check with your supervisor about the noise levels. If it is louder than 115 decibels, it is advisable to avoid such noise exposure during pregnancy. It can be hard to avoid noise at work, but check with your employer if you can work in a quieter job during pregnancy.

- Apart from constant loud noises, sudden loud noises or impulse noise that startle you should also be avoided during pregnancy.

- Sounds appear stronger to your baby when your belly is closer to the source of the noise. So do not lean against anything to place your body in contact with any source of the noise. Also, leaning against a source of vibration should be avoided.

- No matter how much you love that rock concert, it is better to play safe during your pregnancy. So avoid such high noise levels, or position yourself towards the back of the concert hall far away from the speakers.

- If you drive often, avoid playing loud music in your car too.

- Avoid exposing your newborn to loud noises by avoiding visiting places where it can be exposed to loud noises. Well-fitting earmuffs can be used if necessary.