[MI] Medicines and Pregnancy Registry - Antiepileptic use in females aged 0 to 54 in England: April 2018 to March 2024

Register – A female aged 0 – 54 years who has been prescribed one or more prescriptions of antiepileptic drugs in one or more months between April 2018 and March 2024 is deemed to be on the core register and included in the analysis contained in this report.

Age – As at the time of prescription/reporting month. Only those prescriptions reported with an age between 0 and 54 in a reporting month are included. Patients who reach 55 mid-month and receive prescriptions before and after their birthday in the same month, will only have prescriptions issued before their 55th birthday included in the analysis for that reporting period.

Prescriptions/Prescribing – are used interchangeably within the report and refer to those prescriptions that have been prescribed in England AND dispensed in the UK, typically by community pharmacies and dispensing doctors AND have been processed for reimbursement by the NHS BSA for the month of reporting. This means that some prescriptions may have been prescribed and dispensed prior to the reporting month. Private prescriptions are not included in this data.

BNF – The therapeutic classifications used in this report are defined in the British National Formulary (BNF) using the classification system prior to edition 70. ‘antiepileptic drugs’ is BNF section 4.8 and ‘antipsychotic drugs’ is BNF section 4.2. Information on why a drug is prescribed is not available in this dataset. Since drugs can be prescribed to treat more than one condition, it may not be possible to separate the different conditions for which a drug may have been prescribed.

The NHS Business Service Authority, who process dispensed prescription forms and collect dispensed prescribing data and produce the medicines data, continue to use the old BNF classification system to code medicines, which has become widely used in the UK as a classification to allow comparisons between drug groups.

AEDs – are antiepileptic drugs as defined by the BNF section 4.8

APSYs – are antipsychotic drugs as defined by the BNF section 4.2

First trimester – is the month of conception plus the following 3 months unless the month of conception is stated separately in any figures presented in the report.

Rolling quarter – means a consecutive 3-month period and is applied to prescribing data to smooth out the monthly peaks and troughs that occur in prescribing patterns due to patients receiving different quantities of the same drug.