Supplementary material for Psoriasis and adverse pregnancy outcomes A nationwide case-control study in 491 274 women

Background
The chronic systemic inflammation associated with psoriasis supposedly creates an undesirable milieu for a pregnancy, resulting in an increased risk of adverse pregnancy outcomes (APOs).
Objective
To investigate the association between psoriasis and APOs, as well as how the association differs according to psoriasis severity (mild and moderate-severe).
Methods
This nationwide register-based case-control study collected data from 1973-2017. Cases were APOs (spontaneous abortion, ectopic pregnancy (EP), intrauterine fetal death and stillbirth). Singleton live births were controls. Adjusted logistic regression models were used for statistical analyses.
Results
42 041 (8,56%) APOs and 449 233 (91,44%) controls were included. EP was the only APO statistically associated with psoriasis (OR 1.34, 95% CI 1.06-1.68). OR for EP was highest for women with moderate-severe psoriasis (OR 2.77, 95% CI 1.13-6.76). Absolute risk of EP was 2.48% higher for women with moderate-severe psoriasis compared to women without psoriasis (3.98% vs 1.50%).
Limitations
No access to clinical data confirming psoriasis severity.
Conclusion
The present study found a significant association between EP and psoriasis (absolute risk 3.98%). As EP is the leading cause of maternal morbidity and mortality in the first trimester of pregnancy, our findings call for particular care for women with psoriasis of reproductive age.