(B-278) Medication use in the pre-conceptional, pregnancy and post-pregnancy periods, with emphasis on drugs for chronic conditions. Data of the PregVal cohort, Spain (2009- 2021).

Background: The prevalence of chronic conditions in women who enter pregnancy has risen in the last years but evidence on current medication exposure is scarce.

Objectives: To assess the use of medications for chronic conditions in the pre-conceptional, pregnancy and post-pregnancy period, in order to inform potential research priorities.

Methods:

Design: We used data of PREGVAL (pregnancy population-based retrospective cohort -2009-2021) in Spain. Medication use was defined as at least 1 dispensing of the drug of interest. We defined 5 periods: 1) pre-conception (PC) 2) first trimester (T1), 3) second trimester (T2), 4) third trimester (T3), 5) post-pregnancy (PP). Setting: Valencia Health System Integrated database (VID), Spain, covering a population of around 5 million people. Statistical analyses: 1) Descriptive analysis of characteristics of the cohort; 2) proportion of drug use of interest overall and by ATC and period.

Results: Among 520,352 pregnancies during the study period (mean age 31.4 y.), two percent had chronic hypertension, 1.7 % type 2 diabetes and 7.1% depression when entering pregnancy. Regarding drug use, 80% of the cohort had at least 1 medicine dispensed. Chronic conditions drugs accounted for 24.6% of medications used, with the most used ATC being antirrheumatics and antiinflamatory (25.7%), followed by thyroid treatments (11.6%), mainly levothyroxin; corticosteroids in dermatological presentations (7.2%) and anti-asthmatics (5.9%). Regarding utilization patterns, overall, a decrease in use was observed as pregnancy progressed, with a recovery in the post-pregnancy period. It was the case for antidepressants (PC: 2.4%; T3: 0.5%; PP: 1.4%), antipsychotics (PC: 0.6%; T3: 0.1%; PP: 0.5%), antimigraine- (PC: 0.7%; T3: 0.04%; PP: 0.27%) and antiepileptic- (PC: 0.6%; T3: 0.3%; PP: 0.5%) drugs. However, use increased during pregnancy for antidiabetics (PC: 0.6%; T3: 2.0%; PP: 0.6%), antihypertensives (PC: 0.8%; T3: 2.1%; PP: 2.1%) and thyroid treatment (PC: 2.5%; T3: 6.2%; PP: 3.5%).

Conclusions: An important proportion of pregnancies were exposed to medications for chronic conditions, many of which decreased their use as pregnancy progressed. This was the case for drugs aiming to treat mental health problems or neurological conditions. It would be necessary to evaluate the risk-benefit of these interruptions in exposure.