P.F.A. Van Look and H. von Hertzen
Special Programme of Research, Development and Research Training in Human Reproduction,
World Health Organization, 1211 Geneva 27, Switzerland
Few issues in the field of health have evoked such controversy as the subject of induced abortion. As a result, both abortion legislation and provision of services have been dominated more by people’s attitudes and emotions than by public health considerations.
During the latter part of the 19th century and well into the 20th century abortion laws were restrictive in most countries of the Western hemisphere and these laws and attitudes were transported overseas during colonial expansion. The restrictive abortion laws that still exist in many developing countries, particularly in Africa and Latin America, reflect that history.
The world-wide trend towards liberalization of abortion laws started in the Nordic countries in the 1930s when Iceland (1935), Sweden (1937) and Denmark (1938) enacted less restrictive legislation. Most of the countries of Central and Eastern Europe followed the trend in the 1950s, and almost all the remaining developed countries during the 1960s and 1970s. A few developing countries, most notably China and India, also relaxed their restrictions on abortion during the same period.
Currently, some 63% of the world’s people live in countries where abortion is available on request or where social factors can be taken in consideration when evaluating a woman’s request for pregnancy termination (Fig. 1). At the other end of the spectrum, about 25% of the world’s women are subject to the most restrictive laws that prohibit abortion except when the woman’s life would be endangered if the pregnancy continued. For the remaining 12%, abortion is permitted on broader medical grounds and sometimes for genetic or juridical indications, such as rape or incest.
It must be emphasized, however, that this classification of abortion laws depending upon conditions under which abortion is permitted does not necessarily reflect what happens in actual practice, as the interpretation of the same or very similar laws can vary widely between countries and sometimes even within a country. Also, the existence of a liberal law does not necessarily guarantee that abortion services are widely available and accessible and that all abortions are induced under safe conditions. Conversely, women, particularly those from higher socio-economic groups, may be able to obtain safe abortion even in countries with very restrictive legislation. Thus, from a public health perspective, the often used distinction between ‘legal’ and ‘illegal’ abortion is not very meaningful; the more relevant and important distinction is between ‘safe’ and ‘unsafe’ abortions (7).
Every year some 36-53 million unwanted pregnancies are terminated either legally or clandestinely by induced abortion throughout the world (3). The exact number is not known, as statistics on induced abortion are not always reliable due to underreporting even in countries where the practice is permitted and widely accepted, and as there is no adequate method to estimate the number of clandestine abortions. It is estimated that 30-50% of all women undergo at least one induced abortion during their lifetime.
Abortion incidence is usually measured by rates, which relate the number of abortions to population, or by ratios, which relate the number of abortions to the number of births or pregnancies. The two approaches provide different but complementary types of information.
Rates can be calculated and expressed in several ways; for example, per 1000 total population, per 1000 women of reproductive age (defined as 15-44 years) or per 1000 women in defined (e.g. 5-year) age groups. From such age-specific rates one can derive the total abortion rate, which is the number of abortions that would be experienced by 1000 women during their reproductive lifetimes. Abortion ratios are usually expressed per 100 known pregnancies or 100 live births and, like abortion rates, can be calculated for defined age groups.
Table 1 shows examples of abortion rate, abortion ratio and total abortion rate for selected countries thought to have fairly accurate and complete abortion statistics. As can be seen in the Table, abortion rates (and ratios) vary widely between countries as a result of differences in desired family size and, often more important, in availability of—and access to—contraceptive services. Abortion rates and ratios are relatively high in the Central and Eastern European countries; in the former Soviet Union the official data for 1987 indicated a rate of 112 per 1000 women aged 15-44, but estimates derived from survey data suggested that the rate may have been as high as 181. In most of the other developed countries abortion rates range from 10-20 per 1000 women of reproductive age but the USA rate is higher (28 per 1000); the rate for the Netherlands (5.3 per 1000) is the lowest reported rate in the world.
The low rate of the Netherlands illustrates that a liberal position vis-à-vis voluntary pregnancy termination does not inevitably lead to a high number of abortions. Other factors such as easily accessible family planning services including services for adolescents and the provision of emergency contraception, as well as universal sex education at school influence a country’s abortion rate to a much greater extent than the liberal nature of its law.
On the other hand, restrictive laws or lack of access to professional care do not stop women from seeking abortion; only the outcome of the procedure is influenced by such obstacles. If safe services are not available, women resort to clandestine abortion, thus exposing themselves to a high risk of morbidity and mortality. An illustrative contemporary example in this respect is provided by Romania where restrictions on abortion and contraception, imposed during the 1960s, had little effect on the birth rate but did cause a marked rise in abortion-related deaths, which accounted, for example, in 1984 for 86% of all maternal deaths. The number of abortion-related deaths dropped precipitously following the lifting of the restrictions on abortion in December 1989.
While induced abortion is one of the safest surgical interventions in countries where the procedure is legal and appropriate services are widely available, the risk of suffering serious complications and perhaps death is considerable where the operation is performed by an unqualified abortionist under unhygienic conditions. Deaths related to clandestine abortions represent about one-fourth to one-third of the estimated 500,000 maternal deaths that occur each year throughout the world, the vast majority in developing countries (5).
The stage of gestation when a woman presents for abortion is important since it determines the type of procedure that should be used and the risk of morbidity and mortality. The shift toward earlier abortion has been noticeable, particularly in countries where liberalisation of the law was accompanied by the setting-up of adequate and easily accessible services and where women did not face obstacles such as an obligatory waiting period, parental or spousal consent, or other notification requirements.
First trimester abortion
Menstrual aspiration (also known as endometrial aspiration and menstrual regulation) is a variant of vacuum aspiration. The procedure is limited to the first 2 or 3 weeks after a missed period and is generally performed without anaesthesia. A special plastic tube is used with a diameter of 4-6 mm, small enough to be inserted through the cervical canal without dilatation; the tube is attached to a hand-held syringe. Failure to terminate the pregnancy occurs more frequently with this method than with suction procedures performed later in the first trimester. Menstrual regulation has become popular in some developing countries as it is cheap and safe. In some countries where the abortion law is restrictive, menstrual regulation can be obtained in governmental or government-supported facilities provided that pregnancy has not been diagnosed.
Vacuum aspiration is the preferred surgical technique for pregnancies of 6-12 weeks. In vacuum aspiration cervical dilatation is usually needed and either a paracervical block or, less commonly, a general anaesthesia is used. The procedure is usually done on an outpatient basis. The possibility of overlooking an ectopic pregnancy at this stage can be reduced by examining the aspirated material.
Dilatation and curettage, the procedure used before the introduction of vacuum aspiration, is associated with a significantly higher risk of complications and, therefore, should no longer be used.
The shift to earlier abortions may be further facilitated by a wider use of the medical method of antiprogestin-prostaglandin sequential regimen as the efficacy of this method is high within the first two weeks after missed menstruation (up to 98%) (8), the period when surgical methods have the highest failure rate.
Second trimester abortion
In countries with easily accessible family planning services the percentage of second trimester abortions is small and an important proportion of procedures are done on medical grounds (e.g. fetal anomaly). For example, in all Scandinavian countries the percentage of second trimester abortions is well below 5% and in the former Czechoslovakia it was less than 0.5% (3).
There is no ideal method to induce abortion at this stage of pregnancy and this is one of the main reasons why several different methods are being used around the world.
Dilatation and evacuation with forceps and suction curette carried out under either local (paracervical block) or general anaesthesia is the preferred method for terminations in the early second trimester (13-16 weeks’ gestation). To reduce blood loss oxytocin is often used.
For pregnancies of 16 weeks or more non-surgical methods are usually employed such as the intra-amniotic instillation of hypertonic saline, urea or, less often, ethacridine lactate. Alternatives that are gaining more widespread acceptance and use are prostaglandins given intra- or extra-amniotically into the uterus or as vaginal suppositories, intramuscular injections or intravenous infusions. Oxytocin is often added to these regimens.
Prior to inducing abortion in the second trimester it is generally recommended to prime the cervix. In the case of surgical methods this facilitates dilatation of the cervix which in turn allows easier evacuation of the uterine contents and reduces complication rates. In the case of non-surgical abortion prior cervical priming reduces the induction-to-abortion interval. Commonly employed techniques for cervical priming include the use of laminaria tents or equivalent synthetic dilators or of locally or systemically administered prostaglandin analogues. More recently, the antiprogestin mifepristone has been given for this purpose with favourable results. Apart from its effect on the cervix, mifepristone increases the sensitivity of the myometrium to prostaglandins, thus reducing significantly the induction-to-abortion time.
Hysterotomy is rarely indicated for mid trimester abortion as the morbidity and mortality rates are much higher than when using medical methods or dilatation and evacuation.
Morbidity and mortality
It is important to note that despite the advances made in abortion technology, procedure-related morbidity and mortality increase with gestational age. Although second trimester abortion only accounts for a small percentage of all induced abortions it is associated with a disproportionately large amount of morbidity. Two-thirds of major abortion-related complications and half of abortion-related mortality occur in pregnancies terminated after 13 weeks of gestation.
Other factors that influence the risk of induced abortion include the method used, the skill and experience of the practitioner carrying out the abortion, the age and general health of the woman, and the availability and quality of the back-up facilities if complications occur.
In developed countries where abortion is legal and done by a trained person, vacuum aspiration and the medical method of antiprogestin-prostaglandin combination are very safe and effective. In a survey conducted by the International Fertility Research Program (IFRP) the failure rate of vacuum aspiration among 11,309 women who were followed up was 1.2%, while a further 0.9% required curettage because of incomplete evacuation (4). In general, failure-to-terminate rates decrease with advancing duration of amenorrhea and increasing experience of the individual performing the procedure.
Complications of vacuum aspiration are uncommon. As indicated earlier, a major determinant of abortion-related morbidity in the first trimester is gestational age: the rate of major complications is 0.36% at six weeks or less gestation, falling to its lowest level at 7-8 weeks (0.26%) and rising to 1.37% at 13 weeks (2). For example, the risk of haemorrhage (blood loss >500 ml) in vacuum aspiration performed between 9-12 weeks is up to 5 times greater than in procedures performed at less than 9 weeks gestation. Excessive bleeding, infective complications and genital trauma account for nearly 90% of all major complications.
Prospective studies indicate that subsequent pregnancies are not adversely affected in women who have undergone induced abortion. Voluntary interruption of pregnancy is not associated with an increased risk of subsequent adverse psychological or psychiatric sequelae (1), and there is also no evidence that induced abortion, when properly performed, carries an increased risk of secondary infertility. In contrast, if a woman has had one or more clandestine abortions, the probability of her having tubal disease is nearly twice as high as for a woman who never had a clandestine abortion (6).
Death following legal abortion induced in appropriately equipped and staffed medical settings is very rare, with rates ranging from zero to two deaths per 100,000 procedures in the 13 countries for which accurate statistics are available (3). The aggregate mortality rate for these countries is 0.6 deaths per 100,000 legal abortions; this rate is lower than that of tonsillectomy and makes induced abortion about ten times safer than pregnancy carried to term.
Mortality and morbidity attributable to unsafe abortion are difficult to assess and estimates have to be based primarily on hospital records, death certificates and community-based surveys (5). All three approaches have obvious weaknesses. Hospital records are not always efficiently kept and may be inaccurate or the clinical diagnoses and causes of death may be falsified in order to protect people, if the social and legal climate is against abortion. Moreover, hospitals see only the women with complications and it is impossible, therefore, to calculate from this source how many women experience complications and perhaps die without ever receiving medical care. Death certificates are also unsatisfactory as a source of information since many deaths in developing countries are not registered at all and abortion is unlikely to be specified as the cause of death in countries where this could lead to involvement with the police or judicial system. Finally, community-based surveys suffer from the fact that eliciting accurate and complete information about so personal and sensitive a matter as induced abortion is extremely difficult.
Many of the unplanned pregnancies could be avoided by increasing the availability and use of appropriate and affordable methods of family planning. However, it is unrealistic to believe that unplanned pregnancy and induced abortion are entirely preventable. The mere recognition of this fact would go a long way towards finding appropriate solutions for the public health problems associated with unsafe abortion.
- Adler, N.E., David, H.P., Major, B.N., Roth, S.H., Russo, N.F., and Wyatt, G.E. (1990): Science, 248:41-44.
- Henshaw, R.C., and Templeton, A.A. (1993): Curr. Obst. Gynaecol., 3:11-16.
- Henshaw, S.K. (1990): Fam. Plann. Perspect., 22:76-89.
- Laufe, L.E. (1977): Stud. Fam. Plann., 8:253-256.
- Royston, E., and Armstrong, S. (1989): Preventing maternal deaths. World Health Organization, Geneva.
- Van Look, P.F.A., and Bygdeman, M. (1989): Bull. World Health Organ., 67:567-575.
- Van Look, P.F.A., and von Hertzen, H. (1993): Curr. Obstet. Gynaecol., 3:2-10.
- Van Look, P.F.A., and von Hertzen, H. (1993): In: Annual Technical Report 1992. World Health Organization, Geneva (in press).