Women who get pregnant after infertility treatment are more likely to have a stroke in the year following the birth when compared with women who conceived naturally, scientists have found in a new report.
Stroke risk was elevated in the first 30 days after delivery among the women who had undergone treatments, and the odds continued to rise through the year after childbirth.
But the absolute numbers remained very low, the researchers emphasized: just 37 stroke hospitalizations for every 100,000 women who underwent treatment.
There is no need for alarm, the lead author said in an interview. But women seeking treatment should be made aware of a possible link.
Nigeria has one of the highest maternal mortality rates in the world, with 1047 deaths per 100,000 live births, to the World Health Organisation (WHO) Analytical factsheet for March 2023.
The major complications, which account for almost 75 percent of all maternal deaths, are severe haemorrhage, infection, high blood pressure during pregnancy (pre-eclampsia and eclampsia), complications during childbirth and unsafe abortion.
In 2017, Nigeria’s maternal mortality rate was estimated at 917 per 100,000 live births; it increased by nearly 14 percent in 2020 to reach 1047 deaths.
Nigeria is also one of the countries with the lowest contraceptive prevalence rates of 16.64 percent as of 2017, compared with Gambia 16.68 percent, Mali’s 17.24 percent, Niger 18.8 percent and Cameroon 19.3 percent .
In the new study, researchers defined these measures to include intrauterine insemination, assisted reproductive technology, use of a surrogate and fertility preservation procedures.
While infertility treatments are generally safe, some studies have linked them to increased risks during pregnancy, including higher rates of pre-eclampsia, a potentially deadly complication involving extremely high blood pressure — as well as placental abnormalities and preterm birth.
Previous studies of stroke after infertility treatments have yielded mixed results. The new study, published in JAMA Network, is believed to be the largest to examine the risk of hospitalization for stroke among these women.
Read also: Why Nigeria’s fertility challenge persists
It analyzed the health outcomes of 31 million patients who had a hospital delivery in 28 states between 2010 and 2018, including 287,813 who had undergone infertility treatments.
The risk of a hemorrhagic stroke, bleeding in the brain, was twice as high among women who had undergone fertility treatment, compared to those who did not, the study found.
The odds of an ischemic stroke, which occurs when the blood supply to the brain is interrupted, was 55 percent greater, compared with women who conceived naturally.
These results are not the final word on the subject, however.
Just a few weeks ago, the journal JAMA Cardiology published a study that examined long-term health outcomes among women in four countries who had received infertility treatments, and found no evidence of an increased risk for cardiovascular disease.
That study was much smaller, however, including only 2.4 million women.
The new research did not include data about important risk factors for stroke, such as smoking, body mass index, and hypertension.
The scientists took steps to account for the missing data and still found a heightened risk, said the paper’s senior author, Cande Ananth, chief of epidemiology and biostatistics at the Robert Wood Johnson Medical School in New Jersey.
“We know that women who receive infertility treatment have certain vascular complications, typically an increased risk of pre-eclampsia and placental abruption,” Ananth said.
Second, infertility treatments can bring physiological changes, he said. Patients often receive large amounts of estrogen, for example, which can lead to increased blood clotting, a strong risk factor for stroke, he said.
“It is like that people who receive the treatment receive it for a reason. Perhaps there are different biological characteristics” among women seeking treatment, he said.
Still, stroke remains very infrequent among women after childbirth, whether they received treatments or not, Ananth said. “Patients should be aware of the impending risks and counseled appropriately,” he said.