News • November 07, 2025

New Norwegian study on IVF and endometriosis – important research, but no cause for concern

Gurpreet Singh Kalra

Fertility specialist and gynecologist

En large Norwegian registry study has recently gained attention for showing that women born after assisted reproduction (IVF) have a slightly higher risk of being diagnosed with endometriosis or adenomyosis. The findings are interesting – but must be interpreted with caution.

What the study actually shows

The study, conducted by the Norwegian Institute of Public Health (FHI) and published in Fertility and Sterility, included 449,000 women born in Norway between 1991 and 2006. Women conceived after IVF had a relative risk increase of around 49% to get a diagnosis of endometriosis or adenomyosis.

I absolute numbers does this make a difference? approximately 16 cases versus 11 per 10,000 person-years, that is, approximately 5 extra cases per 10,000 women per year of follow-up.

The researchers emphasize that this is a observational study – it shows correlation, not causation.

Important to interpret the findings correctly

The research is based on registry data where diagnoses are mainly registered in the healthcare system without it being known for sure whether they have been confirmed by laparoscopy. The study includes both endometriosis, adenomyosis and related symptoms – so it is not just classic endometriosis that is included in the analysis.

It is also possible that parents who have had fertility challenges themselves are more likely to seek health care for their children later – so-called surveillance biasThis means that more people can be diagnosed without the underlying risk necessarily being higher.

In addition, the data material concerns women born in the 1990s and early 2000s. ART technology, hormone stimulation, and laboratory procedures have changed significantly since then.

What this means in practice

The findings are important and should inspire further research. At the same time, it is crucial to put the results into perspective:

The the absolute risk referred to in the study is low.
The study does not say that IVF Causes endometriosis.
IVF is still a safe, well-documented and globally used treatment method – more than 12 million children have been born after ART worldwide.

Summary

The study shows a context, not a cause.
The absolute increase in risk is small (16 vs 11 per 10,000 per person-year).
IVF technology has developed significantly since the 1990s.

New Norwegian study on IVF and endometriosis – important research, but no cause for concern

What the study actually shows

Important to interpret the findings correctly

What this means in practice

Summary

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