Table 3.

Relative risk of major congenital malformations with exposure to a specific antiepileptic drug monotherapy during the first trimester, compared with unexposed and lamotrigine groups, as reported by the North American AED Pregnancy Registry, 1997–2011

Antiepileptic Drug Monotherapy	Unexposed Reference Relative Risk, 95% Cl	Exposed Reference Relative Risk, 95% Cl
Lamotrigine (n = l562)	1.8, 0.7–4.6	Reference
Carbamazepine (n = 1033)	2.7, 1.0–7.0	1.5, 0.9–2.5
Phenytoin (n = 416)	2.6, 0.9–7.4	1.5, 0.7–2.9
Levetiracetam (n = 450)	2.2, 0.8–6.4	1.2, 0.6–2.5
Topiramate (n = 359)	3.8, 1.4–1.06	2.2, 1.2–4.0
Valproate (n = 323)	9.0, 3.4–23.3	5.1, 3.0–8.5
Phenobarbital (n = 199)	5.1, 1.8–14.9	2.9, 1.4–5.8
Oxcarbazepine (n = 182)	2.0, 0.5–7.4	1.1, 0.4–3.1
Gabapentin (n = 145)	0.6, 0.07–5.2	0.3, 0.05–2.5
Zonisamide (n = 90)	N/A	N/A
Clonazepam (n = 64)	2.8, 0.5–4.8	1.6, 0.4–6.8

Unexposed Reference = Relative risk of major congenital malformations with exposure to each specific antiepileptic drug monotherapy during the first trimester, compared with unexposed subjects or subjects not exposed to antiepileptic drug(s).

Exposed reference = Relative risk of major congenital malformations with exposure to each specific antiepileptic drug monotherapy during the first trimester, compared with subjects exposed to lamotrigine.

Abbreviation: N/A, not available, relative risk not available due to insufficient data.