Use of Contraceptive Pill in nulliparous women associated with three-fold increase in Multiple Sclerosis Risk: Study
Multiple research analyses have been done to ascertain the possibility that oral contraceptive pills would influence the development risks of Multiple Sclerosis (MS). Earlier studies on conflicting viewpoints were unclear whether Oral Contraceptives (OCs) influence the development of MS or not. A new study recently published, looking at information from UK Biobank, was an attempt to clarify the rationale and in particular how parity (having children) and how genetic susceptibility might modify this risk. This was published in the journal Fertility and Sterility by Andrea Nova and colleagues.
This was a population-based cohort study that included 181,058 white women from the United Kingdom born between 1937 and 1970, who were participants in the UK Biobank. A total of 1,131 women were diagnosed with MS. Oral contraceptive use was assessed in terms of ever/never use, current use, duration of use, and age at initiation. The primary outcome was defined as incident MS diagnosis (ICD-10 code G35).
Key Findings
• No case-control comparisons revealed a statistically significant increased MS risk in women who had ever used OCs versus never users, or in current users versus never users.
• The hazard ratio (HR) for ever vs. never users was 1.30 (95% CI: 0.93-1.82, p=0.12), and for current vs. never users, it was 1.35 (95% CI: 0.81-2.25, p=0.25).
• In nulliparous women, which means women that have never given birth, ever use or current use of OCs showed a strongly increased MS risk.
• The HR for ever use in nulliparous women was 2.08 (95% CI: 1.04-4.17, p=0.04), and for current use, it was even higher at 3.15 (95% CI: 1.43-6.92, p=0.004).
• These findings suggest that childbearing without childbirth may be an important modifier of the effect of OCs on MS risk.
• It was also noted that duration of use and age at first use were important.
• Longer current duration and earlier age at first use have been shown to increase MS risk.
• The authors did point out that among women with a lower genetic predisposition to MS polygenic risk score was a stronger association between use of OCs and MS risk.
The study's findings highlight the complexity of the relationship between OC use and MS. While OCs did not significantly increase MS risk in the general population, specific subgroups particularly nulliparous women experienced a much higher risk. This underscores the importance of considering individual factors such as parity and genetic susceptibility when evaluating the potential risks of OC use.
This research suggests that oral contraceptive use, particularly in nulliparous women, may significantly increase the risk of developing Multiple Sclerosis. While the findings provide valuable insights, the authors caution against drawing definitive causal conclusions without further research. Future studies are needed to validate these results across different populations and types of OCs.
Reference:
Nova, A., Di Caprio, G., Baldrighi, G. N., Galdiolo, D., Bernardinelli, L., & Fazia, T. (2024). Investigating the Influence of Oral Contraceptive Pill use on Multiple Sclerosis Risk using UK Biobank data. Fertility and Sterility. https://doi.org/10.1016/j.fertnstert.2024.07.999
