Objective:To explore anti-seizure medication (ASM) treatment patterns, seizures, maternal and fetal outcomes and offspring outcomes of pregnant women with epilepsy (PWWE) who withdraw ASM in the first trimester of pregnancy.Methods:A retrospective analysis was performed on the PWWE database registered in West China Hospital, Sichuan University from January 2009 to October 2022. Patients who withdrew ASM therapy in the first trimester and those who maintained ASM therapy throughout pregnancy were included. Withdrawal in the first trimester was defined as discontinuation of ASM between 0 and 3 months of pregnancy. Sixty-five PWWE (withdrawal group) who withdraw ASM in the first trimester were included, and 130 PWWE (maintained-therapy group) who took ASM throughout pregnancy in West China Hospital during the same period were matched 1∶2. Demographic characteristics, ASM, seizures, maternal and fetal outcomes within 1 year were compared between the 2 groups. In the subgroup analysis, the withdrawal group was divided into a full withdrawal group ( n=53) and a resumption group ( n=12) according to whether the ASM was resumed in the second and third trimesters of pregnancy, and the 2 groups were stratified and compared. Results:In the withdrawal group, the proportion of patients with bachelor degree below [72.3% (47/65) vs 54.6% (71/130), χ 2=5.68, P=0.017], family income less than 5 000 yuan per capita [44.6% (29/65) vs 18.5% (24/130), χ 2=14.98, P<0.001], a family history of epilepsy [12.3% (8/65) vs 3.1% (4/130), χ 2=4.90, P=0.027], and a second pregnancy [43.1% (28/65) vs 26.2% (34/130), χ 2=5.72, P=0.017] was higher than in the maintained-therapy group. The proportion of patients who received multiple ASM was lower in the withdrawal group than in the maintained-therapy group [16.9% (11/65) vs 38.5% (50/130), χ 2=9.35, P=0.002]. In the withdrawal group, the rate of seizures with tonic-clonic seizures during pregnancy [50.8% (33/65) vs 31.5% (41/130), χ 2=6.81, P=0.009] and seizure exacerbation during pregnancy [32.3% (21/65) vs 9.2% (12/130), χ 2=16.41, P<0.001] was higher. The preterm birth rate in the withdrawal group was lower than that in the maintained-therapy group [4.6% (3/65) vs 19.2% (25/130), χ 2=101.70, P<0.001]. The rate of seizure exacerbation during pregnancy was higher in the resumption group than in the full withdrawal group [7/12 vs 26.4% (14/53), χ 2=3.22, P=0.073]. Conclusions:PWWE with a family history of epilepsy and a second pregnancy were more likely to withdraw ASM during pregnancy. After withdrawal, the seizures during pregnancy were significantly worse, but the preterm birth rate of offspring was relatively reduced.