After fertility treatment, they have higher odds of suffering severe bleeding, sepsis and ending up in intensive care than women who conceive naturally.
A study of almost 60,000 women found those who go through IVF are almost 40 per cent more likely to suffer serious complications up to and after giving birth.
It is well known that women over the age of 40 and those who have twins or multiple pregnancies are at higher risk of health problems.
But even taking these factors into account, women who had IVF were still in greater danger of complications, researchers at McGill University in Canada found.
While more research is needed, some experts believe hormones given to these women to stimulate their ovaries may cause harmful changes in the body.
Dr Natalie Dayan, who led the study, said: 'It is important to remember that the absolute number of women who develop these complications remains quite small.'
She added that this means 'for most women who can't conceive naturally', IVF is very safe and effective.
'However, this study highlights the need to ensure optimal health prior to pregnancy, and in some cases, closer monitoring during pregnancy,' Dr Dayan said.
The researchers compared more than 11,500 women who conceived through fertility treatment with a group of 47,000 who became pregnant naturally.
They were matched on characteristics like age and number of previous pregnancies.
The study looked at 44 severe pregnancy complications, from pre-eclampsia to sepsis.
Women who had undergone IVF were more than twice as likely to have at least three of those health problems.
The most common complications were serious infections, severe bleeding after giving birth and being admitted to intensive care.
The start of IVF treatment involves taking hormones to stimulate the ovaries so they produce more than the usual one egg a month.
Doctors need more eggs to fertilise with sperm so they can select the right embryo to put inside a woman and make her pregnant.
However, high doses of these hormones may cause changes to blood vessels which can lead to blood clots in pregnant women.
The authors say more research is needed, which could look at whether freezing women's embryos might protect them during IVF.
Women going back to try for a baby again can avoid potentially damaging hormones if they have a frozen embryo to put into their womb and do not need more eggs to create a new one.
The study, published in the Canadian Medical Association Journal, found at least one complication occurred in almost 31 out of 1,000 women who had fertility treatment.
That was 39 per cent higher than the similar group of naturally conceiving mothers, for whom deaths and complications affected an average 22 out of 1,000.
However, Professor Marian Knight, professor of maternal and child population health at the University of Oxford, said: 'It is possible that the women in the IVF group had more severe pre-existing medical conditions, which could account for their higher risk of pregnancy complications.'
There are more than 68,000 IVF cycles carried out a year in Britain, with more than 20,000 babies born following fertility treatment in 2016.
Another study led by the Netherlands Cancer Institute has looked at the risk of cancer in children born following IVF.
The research, which followed almost 48,000 children for an average of 21 years, con-cluded they are no more likely to get cancer in the long-term.
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