Women who give birth after having fertility treatment are more likely to suffer a stroke than those who conceived naturally, a study suggests.
Researchers at Rutgers University in New Jersey, who tracked 30million pregnancies found women who conceived using fertility treatments such as in vitro fertilization (IVF) or intrauterine insemination (IUI), among others, were 66 percent more likely to experience a stroke within a year of giving birth.
They were twice as likely to suffer the deadlier form of a stroke, a hemorrhagic stroke, when there is a bleed in the brain, and 55 percent more likely to suffer an ischemic stroke, caused by a blood clot cutting off blood supply to part of the brain.
Stroke is the number one cause of death among pregnant women, said to be due to the strain pregnancy puts on the body. About 30 out of every 100,000 women who give birth suffer a stroke up to one year after delivery.
It was not immediately clear why women who received fertility treatments were at higher risk, but the researchers said it could be because of the hormone treatments women undergoing the procedures must take, as well as a higher risk for these women that the placenta does not implant properly.
Researchers at Rutgers University in New Jersey, who tracked 30million pregnancies — including nearly 300,000 involving IVF — found those who used IVF were 66 percent more likely to be hospitalized with a stroke a year after delivery (stock)
This graph shows the raised risk of stroke among women who receive IVF
The number of women getting pregnant via IVF or IUI is continuing to rise as more Americans wait until later in life to start a family. A record number of women in their 40s are now giving birth, official data shows, as the birth rate in the US continues to decline.
IVF is one of several fertility treatments available to conceive a baby. During the process, an egg is removed from the ovaries and fertilized with sperm in a lab. This embryo is then implanted into the woman’s uterus to grow and develop.
IUI is a process that involves injecting sperm directly into the uterus.
While undergoing treatments, patients are injected with the hormone estrogen to stimulate the release of an egg — ovulation — and the growth and maintenance of the uterine lining.
The higher levels of estrogen — which can be well above natural levels — can trigger damage to the lining of blood vessels and raise the number of clotting factors in the blood, raising the risk of a stroke.
In addition to stroke, women who undergo IVF are also at a higher risk of ischemic placental disease — when the placenta is too small or does not attach properly to the uterine lining.
The scientists said this could raise the risk of stroke by triggering high blood pressure as the body attempts to get more blood and nutrients to the uterus, higher levels of inflammation because of stress, and a rise in the number of clotting factors in the blood to avoid a severe bleed.
Scientists also suggested women receiving fertility treatment may have more underlying health risks such as obesity, smoking or alcohol use, all of which can make it more difficult to conceive naturally.
Age was also suggested to be a factor. Although the average age of women using IVF in the study was 32 years old — below the 35-year threshold where risk increases — it was older than those who ‘conceived spontaneously’ in the study, which was 27.
Scientists said the strokes were not occurring until after pregnancy because they were being triggered by a drop in blood pressure as the body returned to its pre-pregnancy state.
In the study, published Wednesday in JAMA Network Open, scientists looked at 30million pregnant women in the Nationwide Readmissions Database, which stores data on patients and whether they were readmitted to hospitals in 28 states across the US.
They reviewed the records of more than 31 million women who delivered babies between 2010 and 2018.
Of the pregnant women in the study, 287,000 — less than one percent — had undergone fertility treatment in order to conceive.
Data showed there was a hospitalization rate of 37 readmissions per 100,000 women within 12 months for those who underwent fertility treatments.
But for those who got pregnant naturally, this rate dropped to 29 per 100,000.
Analysis was then undertaken — adjusting for factors like maternal age, multiple births, hospital type and income — which showed a 66 percent higher risk for women who had had the fertility treatment.
Among women who underwent treatment, 52 — 18 per 100,000 — were hospitalized for a hemorrhagic stroke.
But among those who got pregnant naturally 3,791 — 12 per 100,000 — were hospitalized for hemorrhagic stroke.
Details on how many children each woman gave birth to and whether those receiving fertility treatments were on their first or consecutive pregnancy were not documented.