According to Mayo Clinic, around 18 weeks of pregnancy, fetus becomes able to hear sounds from the outside world. As the weeks pass, babies in the womb even start to respond noise and voices. Most importantly, it is believed that a baby can hear and recognize the voice of his/her mother. This is why it is important for intended parents to talk to their baby who is growing inside a surrogate mother's womb. If you are not physically close to the surrogate mother, with today’s technology, you can record your voice and ask your surrogate mother to play the recording as much as she can so that the baby can hear and recognize his/her parents' voices. 

Pregnancy talk can be a lovely way to connect and start building a relationship with your unborn baby. Even though a baby is not in your womb, this will help them to bond with you. Once the baby is born, the bond will become much stronger as he/she will most likely recognize your voice.