Recent science shows that some DNA of the mother transfers to the child in the womb and vice versa - the literal meaning of blood ties between the baby and the person that carries it.
Also, a baby can hear voices from those around it, and becomes accustomed to the rhythm of the mother’s heartbeat, and no doubt digestive noises as well! It hears the music it’s mother listens to ( or coronation street etc! - you may ban your children from watching certain tv programmes but a baby in the womb hears the voices and picks up any fear or hatred in the voices or background sounds).
Imagine a new born baby taken away from every sound that has become familiar to it during its life, (sound being the only sense from outside the womb that it can experience to any great extent) this is a further trauma to add to that of emerging from a tunnel into a brightly lit noisy, unfamiliar world. . Personally I think that other than in exceptional circumstances, it is vain and selfish to use a surrogate. If you don’t want to carry a child, go without or adopt.