Abortion: Reduced risk of preterm birth?

5. September 2013

Previous studies have shown that abortions are associated with an increased risk of subsequent preterm birth. A new Scottish cohort study now shows that modern abortion techniques can minimise this risk.

Currently, worldwide around 40 million therapeutic abortions are performed per year. Until the 1980s, most abortions were carried out by surgical procedure, over the last two decades abortions performed by means of medical agents have come to predominate – mainly done by using selective progesterone receptor antagonists, such as mifepristone (RU 486) and prostaglandins, which cause the uterus to be less affected. Although surgical procedures (vacuum aspiration, curettage) continue to be employed, prostaglandins are also administered to prevent damage to the uterus. This way the risk of preterm birth (gestation period fewer than 37 weeks) after a previous abortion is successfully reduced. According to the World Health Organisation, there are 15 million preterm births worldwide per year, over a million children die as a result of preterm birth.

The more modern, the fewer preterm births

A recently published cohort study in the specialist journal Plos Medicine analysed data from 732 719 first-borns in Scotland who had entered the world in the 24th week of pregnancy or later during the period 1980-2008. For those women who had an abortion, the risk of future preterm birth was 17 percent higher, among women with two abortions 51 percent and women having had three or more abortions 64 percent higher than for pregnant women without abortion. The greatest risk of preterm birth was reached between 1980 and 1983, with a probability of 32 percent. Between 1984 and 1999, the risk of preterm birth decreased to 20 and to10 percent, from birth year 2000 onward the researchers have no longer been able to note an increased risk. The research team led by Gordon C. Smith of the Department of Obstetrics and Gynaecology at the University of Cambridge suggests that the drop in early birth rate is due to the increased use of medication-based abortion methods. Thus between 1992 and 2008 the proportion involving surgical abortions as the unsupported sole treatment method declined from 31 to 0.4 percent. At the same time the proportion of abortions performed solely with medication increased from 18 to 68 percent. Since accurate data is lacking on the abortion method employed with many instances of abortion, the researchers were able to provide no direct proof. “We do suspect however that the modern methods of abortion can be an effective long-term strategy for reducing preterm birth rates worldwide”, says Smith. The analysis suggests that  surgical procedures solely performed without medicative support were responsible for the previous spontaneous preterm births.

Greifswald Study: abortion increases risk of preterm birth by 15-33%

A study at the Universities of Greifswald, Rostock and the Technical University of Munich from 2008 “on the influence of previous abortions, miscarriages and stillbirths on the rate of newborns with low birth weight and preterm infants as well as on the somatic classification of newborns” showed that abortions, miscarriages or stillbirths increases the risk of a subsequent preterm birth significantly. In an analysis published in the specialist journal “Geburtshilfe und Neonatalogie“, physicians working under study leader Dr. Manfred Voigt of the Centre for Child and Adolescent Medicine, Ernst-Moritz-Arndt University of Greifswald, evaluated data on more than a million first pregnancies from the German national perinatal census during the years 1995 to 2000. The histories of 882 213 mothers recorded as having no previous pregnancy were compared with 52,630 mothers who had undergone one (46,026) or more (6,604) abortions, with 117 784 mothers who had a miscarriage and 3,395 mothers who had brought one or more dead children into the world. After evaluation of the data it turned out that the first-pregnancy women had a preterm birth risk of 7.6 percent. For women who had undergone an abortion, the risk of preterm birth rose to 8.7 percent, for two or more abortions to 10.1 percent. Thus the risk of preterm birth after a single abortion increased by nearly 15 percent, with two or more abortions by a third. For women who had suffered a previous miscarriage, the risk of subsequent preterm birth was 14.1 percent. For women with a previous stillbirth the risk of future preterm birth was 18.3 percent. “In order to reduce incidence of underweight and preterm newborns, it is necessary to investigate the partially or completely unexplained causal relationships with previous abortions, spontaneous abortions and stillbirths in women and to elucidate the underlying pathophysiological mechanisms which are still poorly understood”, states Voigt.

Around the world, preterm births on the rise

According to the WHO report, “Born Too Soon: The Global Action Report On Preterm Birth” from 2012, almost one child in ten enters the world during the 37th week of gestation or earlier. 84 percent of preterm births (12.5 million) occur between 32 and 37 weeks of gestation. The highest rate belongs to the African state Malawi with 18.1 preterm births per 100 births, followed by Congo (16.7%) and Zimbabwe (16.6%). In absolute terms, India with 3.5 million preterm births (13 percent) is in first place. And the United States with 12 percent and Austria with 10.9 per cent also have rates of preterm birth which are in double digits. Germany according to the  WHO has a preterm birth rate of 9.2 percent, in Switzerland the preterm birth rate amounts to 7.4 percent. “To be born too soon is an unacknowledged killer”, says study co-author Dr. Joy Lawn. The number of preterm births in the last 20 years has been a rising one in all countries except three. “About 75 percent of preterm births could be prevented in developing countries using three low-cost measures”, say UN experts. These are the kangaroo technique (increased skin contact between mother to child), steroid injections, antiseptic ointments and the use of antibiotics in the prevention of infections.

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Gynaecology, Medicine

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