As a preofessional pharmacist, you will need to navigate risks when antiepileptics are started in women of childbearing age. Keep in mind, these medications are often used for migraine, mood disorders, fibromyalgia, etc, NOT only seizures.
Weigh teratogenic risk. Generally, feel comfortable if lamotrigine (Lamictal) or levetiracetam (Keppra, Tiratam) is chosen for women who may become pregnant, these medications seem to have the lowest risk. On the other hand, consider valproate as a last resort, it has the highest risk. Think of the risk as falling in the middle with many antiepileptics, including oxcarbazepine and phenytoin. See note, "Medication safety and drug exposure in pregnancy". And be aware that data are limited for some others, such as lacosamide (Lacosamet, andovimpamide) and pregabalin (Lyrica). Consider the indication and potential for pregnancy, then help balance antiepileptic efficacy and risks. Encourage women using ANY antiepileptic during pregnancy to enroll at "AEDPregnancyRegistry.org" website to help researchers learn more.
Recommend optimal contraception. Explain that combo hormonal contraceptive levels are reduced by enzyme-inducing anticonvulsants including carbamazepine, phenytoin, and topiramate. To be safe, suggest an IUD or depot medroxyprogesterone (Depo-Provera, etc) for effective contraception. Tell these patients not to rely on a pill, patch, or ring alone.
Emphasize pregnancy planning. Counsel that antiseizure medications should be optimized well BEFORE pregnancy, up to 12 months if possible since the first trimester is the highest-risk period for birth defects. Advise using at least 0.4 mg/day of folic acid and up to 4 mg/day in some cases. For example, certain antiepileptics (carbamazepine, valproate, etc) can lower folic acid levels or interfere with metabolism.
REFERENCES
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Gynecologic Management of Adolescents and Young Women With Seizure Disorders: ACOG Committee Opinion, Number 806. Obstet Gynecol. 2020 May;135(5):e213-e220. Available at: https://journals.lww.com/greenjournal/Fulltext/2020/05000/Gynecologic_Management_of_Adolescents_and_Young.55.aspx
Tomson T, Battino D, Bromley R, Kochen S, Meador K, Pennell P, Thomas SV. Management of epilepsy in pregnancy: a report from the International League Against Epilepsy Task Force on Women and Pregnancy. Epileptic Disord. 2019 Dec 1;21(6):497-517. Available at: https://pubmed.ncbi.nlm.nih.gov/31782407
Curtis KM, Tepper NK, Jatlaoui TC, Berry-Bibee E, Horton LG, Zapata LB, Simmons KB, Pagano HP, Jamieson DJ, Whiteman MK. U.S. Medical Eligibility Criteria for Contraceptive Use, 2016. MMWR Recomm Rep. 2016 Jul 29;65(3):1-103. Available at: https://www.cdc.gov/mmwr/volumes/65/rr/rr6503a1.htm