BACKGROUND: Evidence informing providers and payers regarding the appropriate management of women with reproductive potential continues to grow and was primarily stimulated by the FDA's Pregnancy and Lactation Labeling Rule. The objective of this analysis was to examine the unmet clinical needs of patients with Crohn's disease (CD) during pregnancy. METHODS: CD patients with pregnancies resulting in live births were identified in the MarketScan® database (1/2010-9/2016) using ICD-CM/CPT/MS-DRG codes. The estimated conception date (index date) was calculated based on the gestational age indicated by the diagnosis or procedure code for delivery. Continuous enrollment from the baseline (BL) period (6-months pre-index) through the postpartum period (6-months post-delivery) was required. Clinical proxies were developed to assess flares during the study period: (1) At least 2 ICD-CM codes for CD-related symptoms: abdominal pain, blood in stool, diarrhea, fatigue, fever, loss of appetite, weight loss, rashes; (2) ICD-CM code for CD-related complication: abscess, anal fissure, arthritis, bowel obstruction/stricture, fissure, fistula, gallstone, inflammation of the eye/mouth, kidney stone, liver disease, ulcers; (3) CD-related hospitalization/ER visit; (4) 60% increase in CD-related outpatient visits from BL; (5) addition or potency increase of oral corticosteroid from BL; (6) addition or dose increase in biologic therapy from BL; and (7) addition of other CD indicated therapies from BL. An assumption was made that only a single flare could occur within 30 days. RESULTS: 1,726 successful pregnancies among CD patients were identified. The mean age was 30.3 years, mean (SD) Deyo-Charlson comorbidity index was 0.1 (0.4), most patients had commercial PPO coverage (63.4%), and the most prevalent comorbid condition was infection (42.5%). There were no significant differences in BL characteristics between pregnancies with and without flares. Among the 1,726 pregnancies, there were a total of 5,074 flares (1,268 flares [25.0%] during the BL period, 2,227 flares [43.9%] during the pregnancy period, and 1,579 flares [31.1%] during the post-partum period). To account for differences in the duration of each peri-pregnancy period (baseline [6.0 months], pregnancy [9.2 months], postpartum [6 months]), average monthly flare rates were calculated. The rates were 211.3, 241.7, and 263.2 flares/month, respectively, for the BL, pregnancy and post-partum periods. The most frequent clinical proxies for flares during the BL period were an increase in CD-related outpatient visits from BL (23.7%) and CD-related symptoms (23.0%). The most frequent clinical proxies for flares during both the pregnancy and postpartum periods were the addition or increase in dose of CD-indicated therapies (45.6% pregnancy period, 35.8% postpartum period) and CD-related complications (25.0% pregnancy period, 35.4% postpartum period). CONCLUSION(S): The consistently high risk of flares during the peri-pregnancy period demonstrates the need for optimizing the management of CD. While sole reliance on claims data is a limitation in assessing poor CD control, the use of clinical proxies to explore national trends in CD disease control might help uncover unmet needs. Healthcare professionals should aim for disease control prior to pregnancy and have a treatment plan during and after pregnancy to optimize clinical outcomes and minimize CD-related complications for women.