It is entirely possible to believe multiple things at once:

1. The drop is fertility is bad for society

2. The drop in teen pregnancy is good, despite it's contributions to 1

3. We should try to fix 1. without undoing 2.

I agree, but I don't think #3 is possible. For a variety of reasons, both biological and societal, the older people get the less likely they are to have kids, and fewer of them.

Fundamentalists, and others who abhor birth control, demonstrate pretty regularly that they have no issue with Teen Pregnancy, but rather unmarried teen pregnancy.

They want married teen pregnancy. By their own admission.