Infertility, pregnancy complications increase risk for future stroke
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Infertility and certain pregnancy complications increased women’s risk for stroke later in life, according to an analysis in the BMJ.
“Our research shows that miscarriage and stillbirths are an indicator that a woman is at an increased risk of stroke; they should discuss their history of these reproductive events with their doctor,” Gita D. Mishra, FAHMS, PhD, CStat, head of the division of epidemiology and biostatistics at the University of Queensland in Brisbane, Australia, told Healio.
Mishra and colleagues analyzed data from eight prospective cohort studies conducted in seven countries to determine the correlation between infertility, recurrent miscarriage and recurrent stillbirth with fatal and nonfatal stroke. Recurrent miscarriage was defined as three or more miscarriages, and experiencing two or more stillbirths was considered recurrent.
With exception of the U.K. Medical Research Council National Survey of Health and Development (NSHD), all included studies began between 1990 and early 2000 and defined baseline as the first instance in which infertility, miscarriage or stillbirth was reported. The NSHD enrolled participants at birth in 1946 and defined baseline as 1982, when stroke information was first collected. NSHD participants retrospectively reported infertility and miscarriage for the first time in 1989.
All studies identified first nonfatal stroke through self-report, five studies identified fatal stroke through death registries and one collected self-reported data on stroke subtypes.
Among 618,851 women (age range at baseline, 32 to 73 years), 275,863 had data on nonfatal and fatal stroke, 54,716 had data on nonfatal stroke only and 288,272 had data on fatal stroke only. Overall, 17.2% of women experienced infertility, 16.6% experiences miscarriage and 4.6% experienced stillbirth.
Infertility
Having a history of infertility increased the risk for nonfatal stroke by 14% (HR = 1.14; 95% CI, 1.08-1.2). Specifically, infertility was associated with a greater risk for ischemic nonfatal stroke (HR = 1.15; 95% CI, 1.07-1.23).
Miscarriage
Miscarriage was associated with an 11% greater risk for nonfatal stroke compared with women who had ever been pregnant but had not had a miscarriage (HR = 1.11; 95% CI, 1.07-1.15).
Additionally, the risk for nonfatal stroke increased with the number of miscarriages. Women with recurrent miscarriage had a greater risk for ischemic (HR = 1.37; 95% CI, 1.23-1.53) and hemorrhagic (HR = 1.41; 95% CI, 1.08-1.84) nonfatal stroke compared with those who did not have a miscarriage.
Similarly, the number of miscarriages increasing was associated with a higher risk for fatal stroke compared with experiencing no miscarriages. Women with recurrent miscarriages were more likely to experience ischemic (HR = 1.83; 95% CI, 1.39-2.41) and hemorrhagic (HR = 1.84; 95% CI, 1.39-2.44) fatal stroke compared with those did no experience miscarriage.
Stillbirth
Among participants who had ever been pregnant, those who had experienced stillbirth had a greater risk for both nonfatal (HR = 1.31; 95% CI, 1.1-1.57) and fatal (HR = 1.07; 95% CI, 1-1.13) stroke compared with those who had never had a stillbirth. The risk for stroke increased with the number of stillbirths for fatal stroke only, according to the researchers.
Women with recurrent stillbirths had a greater risk for ischemic nonfatal stroke (HR = 1.77; 95% CI, 1.54-2.02) and hemorrhagic fatal stroke (HR = 1.44; 95% CI, 1.35-1.53) compared with women who experienced no stillbirths.
“Given that in most cases, the stroke occurred at least a decade after pregnancy loss, the knowledge that a woman is at a higher risk of stroke is an opportunity to monitor her health and for her to make lifestyle changes that can help prevent stroke,” Mishra said. “These include stopping smoking, being physically active and having a healthy diet.”
As for future research, Mishra highlighted a desire to assess “the social and biological mechanisms underlying the associations” between infertility, pregnancy loss and stroke.