pregnancy is a natural process.
I agree that it is a natural process. I also agree that it is involuntary.
Consider menstruation as an example of the same.
Impregnation is an act. When one consents to the action which gives rise to impregnation, one consents to the possibility of the latter.
I don’t have a problem with saying that consent to sex is consent to the possibility of pregnancy, in so far as the possibility is intrinsic to sex and the people involved know that (which would be most people unless they were very, very young).
However, we need to split hairs.
If the people having sex are using contraception, they are clearly not consenting to pregnancy. For what is contraception but the attempt to remove the possibility of procreation from the act?
Let’s consider the Catechism’s definition of contraception (contraceptive act):
“every action which, whether in anticipation of the conjugal act, or in its accomplishment, or in the development of its natural consequences, proposes, whether as an end or as a means, to render procreation impossible” (CCC 2370)
So if the woman becomes pregnant, despite using contraception, and then seeks to have an abortion, it is quite clear to me that she is an example of someone who “did not consent to pregnancy”.
Impregnation merely refers to sexual intercourse that results in conception; more precisely, impregnation is “fertilization”. Fertilization is an effect. Sexual intercourse is the cause.
You have to be careful when saying that willing the cause means consenting to the effect. Again, you’ll have to split hairs. Why? Because otherwise you run the risk of undermining the entirety of the principle of double effect, for example. Which requires the distinction between willing an act without willing the evil effect.
I’m not saying pregnancy is evil. That’s not where I’m going with this. I’m just using the principle of double effect to show that the distinction between willing the cause and willing the effect.
Perhaps you can make a finer distinction between “willing” and “consenting”, if “consenting” is taken to me “tolerating”. Two people who have sex tolerate the possibility of pregnancy, but do not necessarily will it.