The NY Daily News covers the facts in a bit more detail here.
The debate, as usual in these situations, is over whether the need to present proper moral role models to elementary school children (and enforce a certain base level of Catholic morality among employees of Church institutions) outweights the desire not to create an environment in which it is more advantageous to a woman to have an abortion than to carry her child to term.
Commentor Neil quotes a study of the reasons women have abortions:
"The decision to have an abortion is typically motivated by diverse interrelated reasons. Nearly three-quarters of respondents indicated that they could not afford to have a child now, and large proportions mentioned responsibilities to children, partner issues and unreadiness to parent. The in-depth interviews revealed that these reasons are multiple dimensions of complicated life situations. For example, financial difficulties are often the result of lack of support from one's partner, or lack of a partner altogether; and the financial and emotional responsibility to provide for existing children without adequate resources makes it too hard for some women to care for another child."The study thus concludes that most abortions occur because of financial necessity, not "convenience" as critics often accuse. I suspect this is mainly a matter of personal interpretation. I'm sure there are couple who, if in the financial position of the Darwin family and already possessed of two toddlers, would believe that it would be financially impossible for them to have another child.
However, the larger question is: How do you discourage pre-marital sex and any resulting out of wedlock pregnancies without encouraging abortion?
Historically, societies that have sought to discourage pre-marital sex have done so through some combination of punishing men who either take the virginity of women they are not married to or get pregnant women they are not married to and punishing women who either lose their virginity prior to marriage or get pregnant prior to marriage. The two approaches tend to go hand in hand to some extent, since if a woman is severely punished for violating her society's sexual mores, it is more likely that her friends or family will in turn punish the man responsible for putting her in the position to receive that punishment.
Of course, sometimes things break down, and a society chooses to punish almost exclusively one gender and not the other. This usually means punishing the woman for not "maintaining her virtue" and letting the man off with no more than the reputation of being a rake. This is clearly an injustice and should be avoided.
At the same time, if we assume that any single, pregnant woman who is placed in an uncomfortable situation by being pregnant will have an abortion, and that it is thus the duty of pro-life institutions to make sure she is not placed in an uncomfortable situation, we place ourselves an almost impossible task, in that the task of raising a child as a single parent is by definition a very difficult one. Further, human beings being the fallen creatures that we are, people tend to assume that if a particular action carries no visible penalty, that it can't be very wrong. In this sense, by creating an environment in which it a woman who gets pregnant out of wedlock suffers no obvious penalty, we would in essence send the message that acting in that way is basically "okay".
I suspect that in a fallen world achieving the right balance between enforcing rules that make moral lessons clear while treating individual sinners with love and compassion is impossible to get right all of the time. It's not the sort of thing that can be achieved by a blanket administrative policy. Real justice and mercy are necessarily individual.
Our current society tends very much towards the mercy side of the spectrum, especially in cases of sexual sin where (everyone hastens to point out) no crime has been committed. This is partly due to our horror at the incredible levels of suffering sometimes heaped upon unwed mothers and their children a hundred years or more ago -- the sort of thing that made led people describe loss of virginity before marriage to the "the fate worse than death" for a woman. Nonetheless, our efforts as a society to be more supportive of unwed mothers has (in combination with a number of other factors) led to unwed motherhood being very nearly the norm. Now around 40% of children born in the US each year are born to unwed mothers. And since there is a clear, inherent degree of suffering associated with having a child out of wedlock and growing up in a single parent family -- we have got rid of one type of suffering and replaced it with an even more widespread (though lower intensity) variety.
It bears thinking on.