Fertility Trends and Adverse Pregnancy Outcomes in Female Patients With Psoriasis in the UK

IMPORTANCE: Evidence regarding fertility trends and obstetric outcomes among patients with psoriasis is limited by studies of small sample sizes, noninclusion of comparators, and the lack of accurate pregnancy records. OBJECTIVE: To investigate fertility rates and obstetric outcomes of pregnancies in female patients with psoriasis compared with age- and general practice–matched comparators without psoriasis. DESIGN, SETTING, AND PARTICIPANTS: This population-based cohort study used data from 887 primary care practices that contributed to the UK Clinical Practice Research Datalink GOLD database between 1998 and 2019, linked to a pregnancy register and Hospital Episode Statistics. There were 6 223 298 patients of common childbearing ages (15-44 years), and 63 681 patients with psoriasis had at least 1 year of follow-up data prior to the diagnosis of psoriasis. For each patient with psoriasis, 5 patients were matched by age from the same general practice. The median follow-up duration was 4.1 years. Data analysis was performed in 2021. EXPOSURES: Patients with psoriasis were identified using clinical diagnostic codes from consultations. MAIN OUTCOMES AND MEASURES: Fertility rates were calculated as the number of pregnancies per 100 patient-years. The outcomes of each pregnancy recorded in the pregnancy register or Hospital Episode Statistics were screened to identify obstetric outcomes. A negative binomial model was used to examine the association between psoriasis and the fertility rate. Logistic regression was applied to compare the association between psoriasis and obstetric outcomes. RESULTS: A total of 63 681 patients with psoriasis and 318 405 matched comparators were included in the analysis (median [IQR] age, 30 [22-37] years). Lower fertility rates (rate ratio, 0.75; 95% CI, 0.69-0.83) were found in patients with moderate to severe psoriasis. Compared with matched comparators without psoriasis, pregnancies in patients with psoriasis had a higher risk of loss (odds ratio, 1.06; 95% CI, 1.03-1.10); however, there was no increase in the risks of antenatal hemorrhage, preeclampsia, or gestational diabetes. CONCLUSION AND RELEVANCE: In this cohort study, patients with moderate to severe psoriasis had a lower fertility rate, and the risk of pregnancy loss was higher than in matched comparators without psoriasis. Future research should identify the mechanism of increased risk of pregnancy loss among patients with psoriasis.