Most Catholics know the church doesn't approve but they don't know why....
The reason the church is opposed is simply this - surrogacy ends up turning the miracle of birth and the resulting baby
into a commodity which results in tragic circumstances at times.
An essay on Surrogacy puts it this way:
Surrogacy degrades a pregnancy to a service and a baby to a product. Experience shows that like any other commercial dealing the customer lays down his/her conditions before purchasing the goods. The surrogate may be forced to terminate the pregnancy if so desired by the contracting couple and she will not be able to terminate it if it is against the desire of the couple. She has difficulty in keeping her own baby. There have been instances where the contracting individual has specified the gender of the baby as well, refused to take the baby if it is not normal, and filed a suite against the surrogate saying she had broken the contract.The same essay stated that they had interviewed several surrogate mothers and they were not willing to talk about how they felt when they had to relinquish the baby they carried for 9 months to the mother-to-be. One gets the feeling this is very heart wrenching because there is excellent evidence that a woman attaches to her baby pretty early in pregnancy.
A pro abortion sign read "My baby, my body, my choice". Notice the mother is already saying it's HER baby, and not the "products of conception" and not even THE baby but rather HER baby. In other words, the mother is emotionally attaching to the infant in her womb very early in pregnancy.
The article I quoted, calls these ladies, "gestational serfs". Please consider reading this article - it's excellent...just click on the link below:
Gestational Serfs by Wesley Smith, JD