Evidently, the article Michael New was responding to originally appearred on the Law, Religion and Ethics blog. The discussion there is quite good, at a surprisingly high level of sophistication. The Leftys are still wrong however, as this deeply flawed analysis in the comments by June Carbone illustrates:

Well educated women in the US (and women in the Northeast as a whole) have birthrates that look like those in Northern Europe. Well educated women tended to have significantly lower birth rates even during the era when contraception was illegal and I suspect that anyone sharp enough to get into Harvard can figure out how to obtain birth control without a high school class sex ed class. What is different in the US is the relatively high birth rates by poor and minority women, and those high birth rates, which as Koppelman points out reflect dramatically higher rates of unintended pregnancy, involve lesser access to health care, less systematic provision of effective contraception, and (though harder to prove) less ability to say no to unwanted sexual activity. Yet, the teens at greatest risk of early sexual activity are those most likely to be enrolled in abstinence only classes.

Actually, as I have shown many times using Guttmacher Institute data, (See Table 2)contraceptive failure rates are the highest among the young, the poor, and the unmarried, the precise demographic groups to whom it is most heavily marketed.

Those of us who are pro-choice do not embrace abortion as a positive good. Instead, we have no desire to bring back the scarlet letter, and we take the issue of childbearing too seriously to leave it to the vagaries of contraceptive accidents. We would happily join in efforts to reduce abortions by increasing the effectiveness of the contraceptive choices open to women, but we see the real issue as giving more women the opportunity to avoid unwanted pregnancy and childbirth.

How many questions can you beg in one paragraph? The fact is that the whole contraceptive system relies on abortion as a backup plan. No contraception works perfectly. “Avoiding unwanted pregnancy and childbirth” could be accomplished by making more sensible choices about sexual partners and the context of sexual activity. Even if your contraception works perfectly all the time (which it doesn’t), women should still be thinking more clearly about their choices.

But this is evidently not even worth mentioning.