(125) Pregnancy Rates in Patients with Immune-mediated Inflammatory Diseases

Publication Number: 1120

Background: While pregnancy registries for patients with immune-mediated diseases (IMIDs) report on outcomes in patients who become pregnancy, there is limited data on the frequency of pregnancy among women of child-bearing age with IMIDs, particularly as compared to their non-IMID counterparts.

Objectives: To compare the incidence rate of pregnancy among women of childbearing age with select IMIDs relative to patients without IMIDs.

Methods: A retrospective observational claims-based study was conducted using IBM® MarketScan® Commercial and Multi-state Medicaid Database between January 1, 2015 and September 30, 2021. The study population includes women aged 15-44 years diagnosed with rheumatoid arthritis (RA), ankylosing spondylitis (AS), atopic dermatitis (AD), psoriasis (PsO), Crohn’s disease (CD), and ulcerative colitis (UC) and their matched non-disease counterparts. Index date was defined as the first diagnosis of IMID; 183 days of continuous healthcare plan enrolment was required. Each patient with a disease of interest was matched with 2 patients without any IMIDs based on age, insurance type, and calendar time. Diagnosis codes indicating weeks of gestation or pregnancy outcome codes were used to identify pregnancy episodes and the last menstrual period (LMP). Incidence rate (IR) was calculated as the total number of cases divided by total person-years of follow-up, expressed as number of events/100 person-years (100 PY) of follow-up. Univariable Poisson regression model was used to calculate incidence rate ratio (IRR) comparing each disease cohort to its non-IMID counterparts.

Results: The study included a total of 700,965 patients with IMIDs; mean age at LMP ranged from 28 to 33 years, with the youngest in AD and the oldest in RA. Pregnancy rate across IMID (per 100 PY) ranged between 2.59 in RA and 4.25 in UC. Women of childbearing age with IMIDs were less likely to become pregnant than their non-IMID counterparts. IRR was 0.61 (0.56, 0.67) in AS, 0.67 (0.64, 0.70) in RA and 0.70 (0.68, 0.71) in PsO. Patients with AD, CD and UC had comparable IRR of 0.77-0.78.

Conclusions: Women of childbearing age with IMIDs are 22-39% less likely to become pregnant compared to non-IMID counterparts. Future investigations may assess how disease severity, disease activity, and other factors (such as contraceptive use, comorbid conditions, and lifestyle) affect pregnancy rates in IMIDs.