At around 15 weeks old a human foetus starts to hear.
Sounds are muted, but it can hear the mother's heart and digestive system and it's also able to hear voices and other noises from outside the womb.
It's a time when many parents start to interact with their baby, hoping that he or she will be able hear them.
Veena Baggley is five months pregnant with her second child, due in mid October.
She, her husband Scott and her three year old son Hari regularly talk and play music to the unborn child.
Veena says she hopes it is helping to form a bond with him.
"At the moment it's such a big thing in my life. I'm carrying this baby round everywhere, but I don't have any interaction with him, so that's my way of interacting with him. Also I think it's important for him to start hearing our voices, my voice, my husband's voice, my son's voice so that everything's quite familiar when he finally arrives. "
Dr. Vivette Glover is a Professor of Perinatal Psychobiology at Imperial College London.
She agrees that interacting with the unborn child helps the mother form a bond.
"The most important thing is that the mother feels happy and relaxed. She can start to make a relationship with her unborn child while the baby is still in the womb, so if she sings to her lump, massages her lump, talks to the baby while it is in the womb, all that can start to make a relationship which can then means she bonds better with the baby once it's born."
For years Dr Glover has studied and recorded the experiences of pregnant women and potential effects of these experiences during pregnancy on them and their baby in later years.
According to Dr. Glover, forming that early bond is an effective way of lowering the mother's stress levels.
She says: "There's now quite a lot of evidence that if the mother is exposed to stress of various kinds while she is pregnant this increases the risk of a the child having a problem later - it only increases the risk, most children aren't affected, but a child is more likely to have behavioral problem likes ADHD, maybe slower in learning. There are also physical problems, they are more likely to have asthma."
Veena says for her, taking time out to spend with her bump is often the only time she gets to unwind.
She says: "You're so caught up with everything you have to do in the day. In the morning, it's a mad rush to get out of the house, everyone has got to get to work and nursery and then all throughout the day I'm completely occupied with work and I've found particularly second time round, there's not much dwelling on the fact that I'm pregnant, it's just getting on with day to day life, so actually doing things like that gives me a chance to sit down, concentrate on the baby that's coming and myself and really spend some quality time if you like with the unborn child."
But how much can an unborn child actually learn in the womb?
Some parents read to their bumps and even talk to them in a foreign language in the hope of giving their unborn child an early advantage.
Dr. Glover says that while there is evidence to prove that babies can recognize music and voices, it is unlikely that this can improve the intelligence of the baby inside the womb.
She says: "There have been some lovely studies in Northern Ireland where women had been listening to Neighbours - the soap opera Neighbours while they were pregnant. And they compared the babies, the new born babies with those that hadn't been listening to Neighbours and the ones who had been listening to Neighbours, when the tune came on, looked alert and looked around to hear the tune, so there's really good evidence they can learn to recognize music while they are in the womb. This is right at the end of pregnancy when their hearing and responses are already developing."
So trying to teach baby to read or understand another language before he or she is born will not help its development, but that doesn't mean that efforts to communicate with the unborn child are wasted.
Forming a bond between mother and child is vital to ensure a trusting relationship between the two of them and it helps nurture a lifelong attachment.
"If the baby learns to recognize the mother's voice in the womb they are more responsive immediately on birth. A newborn baby is very responsive to the mother. They make eye contact with the mother. If the mother pushes out her tongue, the newborn baby will do that, they are very responsive immediately after birth, they like looking at the mother's face, but they also like hearing the mother's voice."
It's that early bond with mum which will help the child form healthy relationships with other people later in life and teach him or her to deal with a full range of emotions.