Women who have abortions more likely to have premature births in later pregnancies

Women who terminate their first pregnancy with an abortion are at greater risk of giving birth prematurely later in their lives compared to women who do not have an abortion, a study has found.

Scientists said that aborting a first pregnancy increases the chances of a spontaneous pre-term birth in a later pregnancy by nearly 40 per cent. However, women who suffer a natural miscarriage are at even greater risk of having premature babies later on, they found.

The study analysed medical records on 120,000 abortions, nearly 460,000 births and just over 120,000 miscarriages in Scotland between 1981 and 2001. It also compared surgical abortion, when the foetus is removed surgically, with medically-induced abortions using drugs.

It found a significantly increased risk of premature birth with an earlier abortion, but no further increased risk with any subsequent abortions, and a greater risk of surgical abortions compared to medical abortions.

“Many women start their reproductive life with an abortion in their first pregnancy. Up until now what has not been entirely clear is the effect these abortions may have on subsequent childbearing,” said Professor Siladitya Bhattacharya of Aberdeen University.

“Using anonymised Scottish national data, we compared outcomes in women who had an abortion in their first pregnancy with data for women who had a live birth or a miscarriage in their first pregnancy, or who where pregnant with their first child,” he told the British Science Festival.

In 2009, just over 13,000 abortions were carried out in Scotland with the highest rates in young women aged between 16 and 19. In England and Wales, nearly 190,000 abortions were carried out in 2011, with the highest rate in women aged 20.

“We found that women who had an induced abortion in their first pregnancy were more at risk of maternal and perinatal risks in comparison with women who had had a live birth or no previous pregnancy,” Professor Bhattacharya said.

“This risk is not increased any further if you have more than one induced abortion, and very importantly surgical abortion seems to have an increased risk compared to medical abortion,” he added.

The study attempted to take into account any differences in risk between socio-economic groups, but was not able to control for other factors that could have influenced the result, such as smoking.

“The key criticism of what we’ve done is that medical and surgical abortions are done at different stages of gestation, and a lot of the medical abortions we relied on in this study were done in the earlier stages of pregnancy,” Professor Bhattacharya said.

“What we think is going on here is that if there is a greater degree of trauma involved with an abortion procedure that probably is more likely from a physiological point of view to damage the cervix that leads to spontaneous pre-term birth later on, because that is the weakness that allows a pregnancy to slip away,” he told the meeting.

“The hypothesis is that a medical termination is less traumatic than a surgical termination....Bearing in mind all the caveats, it does seem to suggest that there is scope for growing medical abortion,” he said.