Previous abortions linked to adverse birth outcomes – experts respond

One of the largest studies to look at the effect of induced abortions on a subsequent first birth has found that women who have had three or more abortions have a higher risk of some adverse birth outcomes, such as delivering a baby prematurely and with a low birth weight.

The research, which is published online in the journal Human Reproduction today, found that among new mothers, those who had had three or more abortions previously (comprising 0.3% of all first time mothers) were at increased risk of having a baby with a low birth weight or prematurely.

Dr Reija Klemetti, an associate professor and senior researcher in public health at the National Institute for Health and Welfare in Helsinki, Finland, who led the research, said: “Our results suggest that induced abortions before the first birth, particularly three or more abortions, are associated with a marginally increased risk during the first birth. However, the increased risk is very small, particularly after only one or even two abortions, and women should not be alarmed by our findings.”

Our colleagues at the UK SMC collected the following expert commentary. Feel free to use these quotes in your reporting. If you would like to contact a New Zealand expert, please contact the SMC (04 499 5476;

Professor Tom Bourne, Consultant Gynaecologist, Queen Charlotte’s and Chelsea Hospital, Imperial College NHS Trust said:

“The paper is interesting – However the study is observational and as the authors are careful to point out it is very hard to control for all potential confounding variables, and an association certainly does not show causation. So they have shown an association between number of terminations and adverse outcomes later in pregnancy. The confidence intervals for the odds ratios derived overlap 1.0 and so the impact certainly for 1 or 2 previous terminations is marginal and may indeed not exist. The strongest relationship is with very preterm birth – which obviously is a potential concern. The study tells us that women who have undergone terminations may be at risk of problems in a future pregnancy – and in particular very preterm birth. However whether this is secondary to the terminations or some other factor common to these women cannot be derived from the study. Accordingly care should be taken when interpreting the data.”

Andrew Whitelaw, Professor of Neonatal Medicine, University of Bristol, said:

“These results are not completely original but the quality of the study makes them reliable and likely to apply to the UK. This is a high quality study because Finland is a country with excellent and universal data collection on all its residents, linking socio-economic information with medical procedures and health outcomes. While preterm birth before 37 weeks gestation exposes an infant to a modest but definite increased risk of a range of serious problems including brain injury and death, birth before 28 weeks exposes the infant to a hugely increased risk of death, brain injury and permanent disability.  Thus an increase (after 3 or more abortions) of nearly threefold in the odds of having an infant born before 28 weeks is worrying. It is important to realise that medical science has achieved no reduction overall in the percentage of babies born preterm. Quite the opposite, there is a trend in some countries towards an increase. The steadily increasing survival of very preterm infants should not be interpreted as a solution to the problem of preterm birth. Increased survival of infants under 28 weeks is at the cost of increased survival of infants with disability.

Thus the new research findings from Finland should be added to the information given to women seeking termination of pregnancy. The great majority of Finnish terminations were surgical and this can expose the cervix to trauma and may injure the lining of the womb through infection, both processes which are biologically plausible causes of later preterm delivery. It is possible, but not yet demonstrated, that very early abortion induced purely by drugs carries less risk of injury to the uterus and avoids the increased risk of preterm delivery. Future research is needed to compare the long term effects on reproduction of these two methods of termination of pregnancy.”

Dr Patricia Lohr, BPAS Medical Director, said:

“As the authors note, it is impossible to control in these studies for all confounding factors. Any increased risk, if it does exist, is very small, and as the authors stress, a causal relationship cannot be determined. But it is also worth considering how women are expected to use this kind of information. For most women the foremost consideration when faced with an unplanned pregnancy is whether they feel in the position to carry that pregnancy to term and become a parent, or add to their existing family.”