Maternal Health and Antiseizure Medication Use During Pregnancy
Authors:   , Rast Jessica , Lee Brian K. 
Published: November 2022

Antiseizure medications (ASMs) are the main course of treatment for epilepsy and a common treatment for bipolar disorder and neuropathic pain. ASMs are also known teratogens that have been connected to major congenital malformations when used during pregnancy. However, there is not sufficient research evidence to guide clinical practice during this time. A clear picture of current behavior and a deliberate concurrent assessment of ASM risks and benefits is necessary before nuanced guidance can be issued. To this end, the purpose of this study is to 1) present national estimates of the patterns of ASM use around the time of pregnancy, and 2) estimate maternal risks of changes in ASM use during pregnancy. This study was conducted using data from the UK Clinical Practice Research Datalink (CPRD) GOLD, a primary care database, using patient records from 1995-2018. We identified people with ASM indications including epilepsy, bipolar disorders, other psychiatric indications, and somatic conditions including neuropathic pain, fibromyalgia, and recurrent migraine. ASM prescribing during pregnancy increased between 1995 and 2018. Much growth in the use of ASMs during pregnancy was driven by use in indications other than epilepsy, and a substantial portion of ASM users were women without epilepsy. Discontinuation of ASMs during pregnancy was common, particularly among women with an indication for ASMs other than epilepsy: more than two-thirds of women with epilepsy continued to use ASMs during pregnancy, compared to just over 20% of women with other indications. People who discontinued ASM use during pregnancy were less likely to have a seizure than people who continued to use their ASM. Conversely, people who had a lower dosage during the second trimester had a higher prevalence of seizure in the second or third trimester than people who did not change dosage. These differences may be due to differing clinical recommendations based on patient profiles, where a patient who wishes to reduce potential fetal harm may decrease their dose if their condition is not at a low enough risk for worsening to discontinue. These findings suggest that a lowered dose was unsafe for seizure control, and the clinical decision to decrease the dose was less certain in this group of people than the decision to discontinue. In contrast, people who discontinued ASM use in the second trimester were at increased risk for emergency caesarean compared to people who did not change their pre-pregnancy dose in the second trimester. Dosage increases were associated with increased seizure occurrence and A&E visits in the second and third trimester of pregnancy. People who increased their dose in the second trimester were at increased risk for rehospitalization within 30 days of delivery compared to people who did not change their pre-pregnancy dose in the second trimester. Together, these findings may suggest that dosage decrease or discontinuation could lead to increased risk of maternal harm if it does not consider pre-pregnancy maternal health and condition management potential without medication. Many of the indications for ASM use, especially epilepsy and bipolar disorders, often pose increased risk for poor maternal health and obstetric outcomes compared to people without these conditions, another point that should weigh the decision to continue medication use.