Their logic is flawed. They say more abortions happen outside "real" marriages, and since gay marriage isn't "real" marriage it will increase the number of abortions. However, it'd probably decrease it instead -- more people in infertile (not the right word) relationships would reduce the number of unwanted pregnancies.
I'm interested in seeing this "research" on gay parents being actively inferior to straight parents. I'm aware that gay parenting efficacy may be unproven, but no study ever conclusively said "Straights are superior!"
Eleven years isn't a long enough time to see the effects of same-sex marriage? I'm curious to know why the abortion rate rose in Spain, but not the other four countries. Makes me wonder if the rise as anything at all to do with same-sex marriage, since Spain is the only country to show that (according to the article).
So, eleven years isn't long enough to see the effect, yet (In the U.S.) the average marriage length is 7-8 years. Makes sense.