The study, led by Huong Thu Nguyen from the Norwegian Institute of Public Health, analyzed nationwide registry data to determine whether the number of assisted reproductive technology (ART) cycles affects the long-term risk of
hypertension and cardiovascular disease (CVD).
The research team examined women born in Norway between 1965 and 2000 who were alive and residing in the country as of 1 January 2009. ART exposure was identified through dispensed prescriptions linked to fertility treatments, allowing the researchers to track the number of cycles each woman underwent.
Using Cox regression models, the investigators assessed outcomes in more than 1.6 million women, of whom over 42,000 had undergone ART. The median follow-up period was 12 years. Their analysis adjusted for several confounding factors, including age, educational status, diabetes, polycystic ovary syndrome, endometriosis, and parity. The risk was analysed in two ways—using both ART-naïve women and those with a single ART cycle as reference groups.
The results showed a clear pattern:
- Every additional ART cycle was associated with a slight increase in cardiovascular disease risk (HR 1.07).
- The link between ART cycles and chronic hypertension was minimal, with hazard ratios indicating no significant increase (HR 1.02).
- The rise in cardiovascular disease risk was mainly driven by thromboembolic events, including pulmonary embolism and deep vein thrombosis.
- Women who had undergone four or more ART cycles showed some indication of higher cardiovascular risk (HR 1.34).
- Programmed frozen cycles were associated with a more notable increase in cardiovascular disease risk (HR 1.35).
The lay summary included by the authors reiterates that while chronic hypertension did not show any significant rise, cardiovascular events—primarily those related to blood clots—became more frequent with increasing ART exposure. The findings suggest that as the number of cycles rises, so does the likelihood of thromboembolic complications.
The authors emphasise that although the dose-response relationship remains somewhat uncertain, the overall pattern indicates that women undergoing ART have a greater risk of cardiovascular disease compared with those who do not pursue fertility treatment. They recommend that further research with longer follow-up and more detailed data on lifestyle and cardiovascular risk factors is needed.
"Even so, the study supports the idea that women undergoing ART, especially repeated or programmed frozen cycles, may benefit from more vigilant monitoring of their cardiovascular health," the authors concluded.
Reference:
Nguyen, H. T., Hanevik, H. I., Fraser, A., Lawlor, D. A., Furu, K., Cohen, J. M., & Magnus, M. C. Women’s risk of hypertension and cardiovascular disease subtypes by number of cycles of assisted reproductive technologies: A Norwegian registry-linkage study. European Journal of Preventive Cardiology. https://doi.org/10.1093/eurjpc/zwaf719
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