By the time you accomplish your 3rd trimester, your piddling 1 is eavesdropping on your conversations, hearing the audio of your heartbeat, and even enjoying the music yous mind to. But it takes a while for this to happen, and there are many steps along the fashion. Find out how your baby's ears and hearing develop inside the womb.

When tin a fetus hear?

Between xvi and 22 weeks of pregnancy, your babe may start to hear faint sounds inside your torso such as the noise made by your breathing, heartbeat, and digestion. These sounds will grow louder as your baby'due south hearing improves.

After 23 weeks, your baby can hear sounds from the outside earth, including your voice. At offset, your baby'due south ears tin can hear simply low-pitched sounds, pregnant babies in the womb can generally hear male person voices improve than female voices. Withal, your own voice will sound loud to your baby considering it'southward shut and reverberates through your body every bit yous speak. Research shows babies learn to recognize their female parent's voice within the womb, and show a clear preference for her voice over others.

Every bit your baby's ears and brain mature, they'll gradually perceive a wider range of sounds, including more voices in the higher ranges.

At effectually 26 weeks, your baby may brainstorm to answer to the sounds they hear with changes in their heartbeat, breathing, and motion. If the noise is particularly loud, your babe may startle – and you might feel your baby move. Ultrasounds have besides caught changes in babies' facial expressions when they hear music.

illustration of hearing development in fetus

When do babies develop ears?

Your babe's ears start developing in the first weeks of pregnancy, and aren't fully formed until the third trimester. The ear is a remarkably circuitous organ, with three carve up parts (the inner ear, middle ear, and outer ear). Each of these structures develops on its own timetable.

  • Inner ear evolution. By 5 weeks of pregnancy, two small spots announced on either side of your infant's head – these eventually become the inner ears. Soon they'll start to fold inwards and form sacs just beneath the surface of your baby's peel. The sacs so lengthen into a tube, and the principal organ of hearing (cochlea) takes shape at the end.
  • Middle ear development. Around 8 weeks of pregnancy, the ear basic – tiny structures that vibrate and help procedure sounds – brainstorm equally small clumps of tissue that slowly harden over the coming weeks. A tube-like cavity that will become the center ear begins to form around these structures.
  • Ear-brain connection. Around 12 weeks of pregnancy, specialized audio transmitters called pilus cells spring up within the cochlea and eventually connect to a nerve that sends audio impulses to the brain. This connexion is made at nigh 16 weeks, when your baby may first to hear faint sounds.
  • Ears fully formed. Past 32 to 35 weeks of pregnancy, the middle ear cavity, outer ear culvert, and outside part of the ear are fully formed. Your infant is ready to listen and answer to the sounds they'll hear equally soon as they're born.

What babies hear in the womb

The noises and voices your baby hears from the outside globe audio muffled. That's because they have to pass through multiple layers, including your skin and the wall of your uterus as well every bit the amniotic fluid. Plus, it'south noisy inside your uterus – sounds from your animate, heartbeat, and digestion are equally loud to your baby as a washing machine.

That said, your babe will hear your voice more clearly than all others. That'due south because the sound of your voice reverberates through your trunk when you lot speak. Research suggests babies in the womb may go more alert when they hear their mom talking or reading aloud.

Sounds your babe hears in the womb contribute to hearing and brain development, which will continue once your babe is built-in. Yous and your partner don't demand to do annihilation special to facilitate this.

How to back up your baby's hearing during pregnancy

You can take steps to protect your baby's hearing such as:

  • Exist conscientious with medications. Taking sure drugs during pregnancy, including some antibiotics, has been linked to hearing loss in babies. Tell all your health care providers (even your dentist) that you lot're significant, and talk to your dr. or midwife to brand sure you're taking safe medications for pregnancy.
  • Avoid prolonged, very loud dissonance. At that place's some evidence that long-term exposure to very loud noise – like 8 hours a solar day, every day – can impairment your baby's hearing. Some experts recommend avoiding any routine noise louder than 115 decibels (almost every bit loud every bit a chainsaw) while pregnant. It's best to avert any noises louder than that, such every bit a stone concert or shooting range, as much as possible. That's true even if you're wearing hearing protection, because the racket tin still travel through your body to your baby's ears. If you lot work in a very loud environment (say with noisy machinery or at loud events) you lot may want to inquire your employer if you can work in a quieter location for the duration of your pregnancy.
  • Eat fish that'southward low in mercury. Fish is full of healthy omega-iii fatty acids that help your babe's brain grow and develop, simply some kinds also comprise high levels of mercury – which has been linked to certain birth defects, including hearing loss. To residuum these risks and benefits, the U.South. Food and Drug Administration advises meaning women to consume 8 to 12 ounces a week of depression-mercury fish. Eat a diversity of safe fish (such as salmon, cod, shrimp, and tilapia), and avoid the four types of fish that have the highest amounts of mercury: swordfish, tilefish, shark, and king mackerel.
  • Don't drink booze. Drinking during pregnancy can cause a grouping of birth defects known as fetal alcohol spectrum disorders (FASDs). Children with an FASD can have hearing loss and trouble with voice communication. No one knows how much alcohol it takes to cause the condition, then information technology's best to exist on the safe side and avert alcohol altogether.
  • Play music. There'southward no show to support the myth that playing Mozart or other music for your infant in utero will make them smarter. However, bear witness suggests listening to music (as well as people talking and other sounds from the environment) can help develop your baby's hearing, memory, and emotions. To protect your baby'southward delicate ears, brand certain the music isn't too loud. Never identify ear or head phones directly on your belly, as the sound will dilate to dangerous levels as it travels to your baby.

Milestones in baby hearing development

Weeks pregnant What's happening
five weeks Inner ear starts to develop.
12 weeks The cochlea and middle ear are forming, and pilus cells begin to sprout.
16-22 weeks Your baby tin hear sounds inside your body, like your center beating.
23 weeks Your baby can hear sounds from the outside world, like a dog barking.
26 weeks Your babe can hear a broader range of sound and can respond with changes in heartbeat, breathing, and movement.
32-35 weeks All parts of the ear are completely formed, and your baby'due south hearing continues to be fine-tuned.

Acquire more:

  • Video: How your babe's sense of hearing develops
  • Music and your unborn child
  • Slideshow: Fetal development, week by week