Does talking to a baby while still in womb have any positive impact? Have there been studies that prove this...

Yes, researchers and studies say that babies do hear in the womb and it affect the baby. Like you may have heard how in Mahabharata, Abhimanyu learnt the skill of coming out of the Chkravyuhu when he was still in his mother's womb. Only at five months the foetus startles at the light blinking on mother's tummy. The baby responds to the sound of music. One can see how the baby in the womb frowns and changes expressions. Mother's emotions are for-related to a baby in the womb, which is why woman who is expecting is told to stay happy and enjoy the time. If the mother is anxious during the pregnancy, she has the tendency to give birth to a baby who is anxious. This all happens because all emotions do not pass the placenta but the stress hormones do. These stress hormones are called catecholamines. So, when the mother remains stressed often these hormones cross the placenta and frighten the developing nervous system of the baby. So, it is very important that mothers listen to good music, remain happy and eat healthy to have a positive impact on the developing baby.