In countries where abortion is illegal, there is a higher number of abortions, a vastly greater chance of women ending up in the hospital due to complications from unsafe abortions and an exponentially increased chance of women dying from unsafe abortions.
In the prestigious British medical journal, The Lancet, a team of researchers (Gilda Sedgh et al.) tracked abortion rates worldwide from 1995 to 2008. (In order to access the full text, you must login. It is free. I have provided snippets below). [Publish date February 18, 2012. The Lancet Vol. 379 No. 9816 pp 625-632 and comment pp 594-596]
Worldwide, 49% of abortions were unsafe in 2008, compared to 44% in 1995. About one in five pregnancies ended in abortion in 2008. The abortion rate was lower in subregions where more women live under liberal abortion laws (p<0·05).
The substantial decline in the abortion rate observed earlier has stalled, and the proportion of all abortions that are unsafe has increased. Restrictive abortion laws are not associated with lower abortion rates.
For further elaboration on what determines unsafe abortion, they state their methodology:
As elaborated by WHO,4, 11 abortions done outside the bounds of law are likely to be unsafe even if they are done by people with medical training for several reasons: such procedures are usually done outside facilities authorised to perform abortions, sometimes in unsanitary conditions; the woman might not receive appropriate postabortion care; medical back-up is unlikely to be immediately available should an emergency arise; and the woman might delay seeking an abortion or seeking care for complications because the abortion is clandestine. Thus, as in previous efforts to estimate abortion incidence and consistent with WHO practice, we used the operational definition of unsafe abortions, which is abortions done in countries with highly restrictive abortion laws, and those that do not meet legal requirements in countries with less restrictive laws. Safe abortions were defined as those that meet legal requirements in countries with liberal laws, or where the laws are liberally interpreted such that safe abortions are generally available. Countries with liberal laws were defined as those where abortion is legal on request or on socioeconomic grounds, either with or without gestational limits; and countries whose laws allow for abortion to preserve the physical or mental health of the woman, if these laws were liberally interpreted, as of 2008. To the best of our knowledge, Hong Kong Special Administrative Region, Israel, New Zealand, South Korea, Spain, and Ethiopia met the latter set of criteria. The classification of countries according to whether their abortion laws are liberal or restrictive is provided in thewebappendix and reviewed elsewhere.12 Although the legal status of abortion and risk associated with the procedure are not perfectly correlated, it is well documented that morbidity and mortality resulting from abortion tend to be high in countries and regions characterised by restrictive abortion laws,4—6 and is very low when these are liberal.
They discuss these findings by stating that in 2008 nearly half of all abortions worldwide were unsafe.
We found that the proportion of women living under liberal abortion laws is inversely associated with the abortion rate in the subregions of the world. Other studies have found that abortion incidence is inversely associated with the level of contraceptive use, especially where fertility rates are holding steady,36—38 and there is a positive correlation between unmet need for contraception and abortion levels.36 The unmet need for modern contraception is lower in subregions dominated by liberal abortion laws than in those dominated by restrictive laws, and this might help explain the observed inverse association between liberal laws and abortion incidence.39 Global levels of unmet need and contraceptive use seem to have stalled in the past decade: the percent of married women with unmet need for contraception fell by 0·2 percentage points per year in 1990—2000, but essentially did not change in 2000—2009.39 Family planning services seem to not be keeping up with the increasing demand driven by the increasingly prevalent desire for small families and for better control of the timing of births.
However, a liberal abortion law alone does not ensure the safety of abortions. Other necessary steps include the dissemination of knowledge about the law to providers and women, the development of health-service guidelines for abortion provision, the willingness of providers to obtain training and provide abortion services, and government commitment to provide the resources needed to ensure access to abortion services, including in remote areas.
… We found that abortions continue to occur in measurable numbers in all regions of the world, regardless of the status of abortion laws. Unintended pregnancies occur in all societies, and some women who are determined to avoid an unplanned birth will resort to unsafe abortions if safe abortion is not readily available, some will suffer complications as a result, and some will die. Measures to reduce the incidence of unintended pregnancy and unsafe abortion—including improving access to family planning services and the effectiveness of contraceptive use, and ensuring access to safe abortion services and post-abortion care—are crucial steps toward achieving the MDGs.
They further offered commentary on this issue (Abortion: what is the problem?):
The publication of Gilda Sedgh and colleagues’ article in The Lancet coincides with the anniversary of the Roe v Wade US Supreme Court decision that effectively legalised abortion in all 50 states. In the nearly three decades that have followed this landmark decision, there has been no letup in the controversy surrounding abortion. In fact, discussion of abortion has become so fraught with symbolic and real controversy that even the scientific literature has not been spared. In The Lancet, Gilda Sedgh and colleagues1 present an article on global abortion rates and trends that will generate debate on tricky methodological issues in tallying the frequency of an act that is often highly stigmatised, frequently illegal, and commonly secret. This study1 should also draw attention to the impact of health-care access, politics, and religion, and how these factors intersect to produce global patterns of death from abortion.
Beneath the manifest problems in documenting abortions and parsing them into safe and unsafe categories lies profound irony. Unsafe abortion is one of the five major contributors to maternal mortality: causing one in every seven or eight maternal deaths in 2008.6 Yet, when abortion is provided with proper medical techniques and care, the risk of death is negligible and nearly 14 times lower than that of childbirth.7 Almost the entire global burden of deaths due to abortion occurs in Africa, Asia, and Latin America.6 Somehow, we typically act as if this were neither surprising nor troubling. But there are no regional biological differences in women that could account for this discrepancy; there is no procedure to prevent death from abortion that is unknown to practitioners where the toll is high; and there are no costly technologies needed to avoid these deaths. If a lack exists, it is a lack of caring: a willingness to sacrifice lives to an ideological moral high ground, to social acceptability, or to the maintenance of a political comfort zone.