Women who have had an abortion are more likely to give birth to a premature baby and to suffer several other pregnancy complications when they next conceive, new research has suggested.
A major study that looked at more than a million pregnancies in Scotland over 26 years has revealed that women who have had one termination are 34 per cent more likely to have a premature birth than those pregnant for the first time. Their chances of pre-term delivery are 73 per cent higher than women having a second baby, who are known to have a lower risk of preterm delivery.
The risks of prematurity increase sharply with more than two abortions. One in five women who has had four terminations will give birth before 37 weeks, compared with fewer than one in ten women who have had only one, according to preliminary results from the University of Aberdeen.
Women who had surgical abortions were 27 per cent more likely to have preterm births than those who had medical abortions with drugs, which are more common earlier in pregnancy. The study also linked a previous abortion to slightly higher risks of stillbirth and pre-eclampsia, a blood pressure disorder that can itself lead to pre-term delivery and occasionally threatens the lives of mothers and infants.
The findings will add to controversy over the health implications of abortion as the House of Commons prepares to debate an amendment to the Health and Social Care Bill that would give women who want a termination a legal right to independent counselling.
Sohinee Bhattacharya, who led the research, said women considering abortion should be told about the link to pre-term birth, though she cautioned that the vast majority can still expect a normal healthy pregnancy.
“I think that it’s something that should be brought to the notice of women, but the absolute risk isn’t large,” she said.
As the risk of pre-term delivery in a first pregnancy is about 6 per cent, the overall risk to women who have had one abortion is still less than 10 per cent, so more than 90 per cent will not give birth prematurely.
Some or even all of the effect, she added, could be explained by risk factors such as smoking, age and lower social class that are more common among women who have abortions, and which are also causes of preterm birth. The study did not control for the effects of smoking, a major cause of prematurity, because of insufficient data.
“The risk factors that are present in women who go for a termination are also the same risk factors that are responsible for preterm delivery,” Dr Bhattacharya said. “The group of women who have a termination are also possibly the same group of women at highest risk for pre-term delivery.
“The other possible explanation is the method of termination. Surgical terminations had a higher risk of pre-term delivery than medical terminations, so it could be that trauma to the opening of the uterus could result in some kind of damage that possibly results in increased risk.”
The risks of prematurity are also similar following both abortion and miscarriage, suggesting that similar effects may be responsible. Women who have had an abortion were also less likely to have an ectopic pregnancy or miscarriage than those with a previous miscarriage.
Preliminary results from the research, led by Dr Bhattacharya and Professor Siladitya Bhattacharya, were presented at the European Society of Human Reproduction and Embryology conference in Stockholm yesterday. The work has not yet been published or peer-reviewed.
The study examined the Scottish Morbidity Records for all women in the country aged 15 to 55 who had two pregnancies between 1981 and 2007. They identified 171,208 women who had a second pregnancy after an abortion, 6,098 who had a second pregnancy after miscarriage, 458,337 who had a second pregnancy after a live birth, and 458,339 women pregnant for the first time.
Ann Furedi, chief executive of the British Pregnancy Advisory Service, said: “Several studies have shown a small increased risk of pre-term birth after abortion, but it is often very difficult to control for all the other factors which may put these women at risk of pregnancy complications anyway — such as being older, more likely to smoke, or being more socially deprived.
“However, we are interested in the suggestion that women who have had an abortion are at no greater risk of delivering a subsequent pregnancy prematurely than those who have had a miscarriage, and indeed are less likely than these women to go on to have a miscarriage.
“These are early results, and we look forward to reading the study when it is published in full.”
Josephine Quintavalle, of the ProLife Alliance, said: “This is the most compelling evidence to date of the health impact of abortion on future pregnancies. Whatever one’s position on the ethics of abortion, it is more than obvious that alerting patients to the very real and incremental risks of future miscarriage should now be an essential part of informed consent protocols.”
Tony Rutherford, chairman of the British Fertility Society, said: “It is important to put into perspective that the overall risk to women who have had a termination of having a complication is still extremely low. But there is, perhaps understandably, an increased risk following instrumentation to the uterus. It is good to get data like this because it allows us to counsel our patients accordingly.”
· The Government released figures on late abortions after a High Court ruling yesterday. Data showed that there were 147 terminations carried out after 24 weeks during 2010. It also showed that 66 late terminations were due to problems with the nervous system, such as spina bifida. The ruling followed a challenge by the Department of Health.
Separate research has suggested that women who have had an abortion are 34 per cent more likely to give birth to a premature baby. A study found that women who have had one termination are 34 per cent more likely to give birth prematurely than those pregnant for the first time, according to the research by the University of Aberdeen.