The new study was led by Catherine Pirkle, Ph.D., an assistant professor in the Office of Public Health Studies at the University of Hawaii at Manoa in Honolulu. The first author of the paper is Nicole Rosendaal.
Prof. Pirkle and her team examined the data available on 1,047 women from the 2012 International Mobility in Aging Study (IMIAS). The women were between 65 and 74 years old and were living in Albania, Brazil, Canada, and Colombia.
Having obtained information on the age of the women’s first pregnancy, the researchers used the Framingham Risk Score (FRS) to check for correlations with cardiovascular disease risk.
Cardiovascular disease — understood as heart disease and the blood vessel-related problems that give rise to it — is the leading cause of death among both men and women in the United States.
Teen moms at long-term cardiovascular risk
The new study found that women who had their first pregnancy before the age of 20 had a much greater long-term risk of cardiovascular disease than women who became mothers after that age.
Additionally, women who had never given birth had the lowest cardiovascular risk, as measured by the FRS.
Speaking to Medical News Today about the strengths of the study, Prof. Pirkle deemed the findings “robust.” She explained:
“Women who participated in our study came from five very different study sites. We observed a relatively consistent association in which early childbearing was associated with greater cardiovascular disease risk across study sites, which supports the validity of our results.”
Strengths and limitations of the study
In addition to the diverse sample of the study, Prof. Pirkle spoke to MNT about its other strengths, such as the researchers having used the laboratory-based version of the FRS to measure heart disease risk.
“Because this version of the [FRS] largely uses biomarker measures (e.g., blood test results) and clinical measures (such as blood pressure),” Prof. Pirkle explained, “It is less prone to the biases often encountered in observational epidemiological studies that rely on participant self-report.”
“We also repeated our analyses using office-based [FRS],” she added, “which are what doctors might ask during a clinical evaluation, and observed very similar results.”
The study authors admit, however, that the study has some limitations. For one thing, the research used data as they were reported by the study participants, who were seniors. This puts the study respondents at risk of memory loss, which may have biased the results, says the team.
Prof. Pirkle shared with us an additional potential limitation, which also has to do with the advanced age of the participants.
“Because the IMIAS includes study sites from middle-income settings,” she explained, “especially Brazil and Colombia, where premature mortality was high when these women were younger, there is a possibility that we only selected ‘survivors’ for our study.”
“It is possible that women who were at highest risk of cardiovascular disease mortality died before we could recruit them to our study. This is termed survivor bias,” Prof. Pirkle continued.
Possible explanations for the results
Although this was an observational study that cannot explain causality, Prof. Pirkle shared with us two potential explanations for the strong association between teen motherhood and heart disease risk.
These mechanisms “are not mutually exclusive,” she said.
“The first mechanism,” Prof. Pirkle went on, “relates to the consequences of adolescent pregnancy and childbirth […] Adolescents who have children early in life may have [fewer] opportunities to finish school and to earn sufficient incomes over their lifetimes.”
Source: Medical News Today