Abortion as a "Form of Birth Control"

Raphael G. Satter writes in British Lawmaker: Abortions Too Common (London/AP):

The architect of Britain's abortion law said Wednesday that the procedure was too common and some women were using it as a form of birth control.

Lord David Steel, who introduced the 1967 Abortion Act that provided a legal defense to doctors performing the procedure, said that while he was proud of his achievement, too many women were terminating their pregnancies for the wrong reasons.

In an op-ed piece in the Seattle Post-Intelligencer, Joan Smith (a reporter for the Independent (UK)), responds:

Women -- I mean, what are we like? Having abortions for totally trivial reasons, like not wanting to be pregnant! You'd think by now we'd have got it into our heads that abortions are only for women who really deserve them, which basically means anyone who has been raped (though not according to the Vatican) or can show that they're really, really upset.

What does it mean to use abortion as  "form of birth control" anyway?  I assume that, when people say this, they envision a woman who routinely has unprotected sex knowing she doesn't want to have a child, and who then resorts to an abortion should she become pregnant.  (Of course, the accusation wholly ignores the responsibility of the male partner, who presumably also "uses abortion as a form of birth control" by failing to use a condom.)

But before hurling the old "abortion as birth control" accusation, it's important to be aware of the facts.  Women are at risk of pregnancy for over three decades of their lives, and they spend most of this time trying to avoid becoming pregnant. 

So why do women end up needing abortions?  My hunch is that most women (1) use contraception, but do so imperfectly; (2) practice abstinence, but do so imperfectly; or (3) some combination of (1) and (2).  Indeed, in busting the myth that "women are using abortion as birth control," the Guttmacher Institute points out:

[H]alf of all women getting abortions report that contraception was used during the month they became pregnant. Some of these couples had used the method improperly; some had forgotten or neglected to use it on the particular occasion they conceived; and some had used a contraceptive that failed. No contraceptive method prevents pregnancy 100% of the time.

If abortion were used as a primary method of birth control, a typical woman would have at least two or three pregnancies per year -- 30 or more during her lifetime.

In fact, most women who have abortions have had no previous abortions (52%) or only one previous abortion (26%). Considering that most women are fertile for over 30 years, and that birth control is not perfect, the likelihood of having one or two unintended pregnancies is very high.

Do you know any woman who has had thirty abortions?  Neither do I.