Objective To investigate the effect of fluoxetine-exposure during pregnant period on depression-like behaviors and hippocampal BDNF in offspring mice.Methods Sixteen C57BL/6 pregnant mice were randomly divided into fluoxetine group (Flu group) and normal saline group (NS group),including 8 mice in each group.And the mice in the Flu group and NS group were treated with fluoxetine (10 mg/kg) and normal saline respectively by intragastric administration from the date of conception 9 to day 18.The adult offspring mice were divided into 8 groups including 4 subgroup with 8 in each group based on gender and circadian rhythm.That was Flu-MD group,Flu-MN group,Flu-FD group,Flu-FN group,NS-MD group,NS-MN group,NS-FD group and NS-FN group;"M" and "F" stands for gender;and "D"and "N" stands for circadian rhythm.The depression-like behavior of offspring adult mice was observed by tail suspension and forced swimming test,and the expression of brain derived neurotrophic factor (BDNF) in hippocampus was detected by Western blot.Results (1) There was no deformity in the adult offspring mice of NS group and Flu group;(2) In the tail suspension test and forced swimming test,there was no significant difference in cumulative immobility time between the Flu group and the NS group (P＞0.05).There was no significant difference in cumulative immobility time between male and female mice in NS group or Flu group (P＞0.05).There were significant differences in immobility time between Flu-MD group and Flu-MN group (tail suspension test:Flu-MD group (175.94± 30.93)s,Flu-MN group (127.65±44.91)s;forced swimming test:Flu-MD group (108.17±44.92)s,Flu-MN group (169.00±62.50) s,P＜0.05),and there were no significant difference in the rest groups.(3) There was no significant difference in the expression of BDNF protein between the Flu group and NS group (P＞0.05).Conclusion There is no phenotypic abnormalities on offspring when female mice were exposed to fluoxetine during their pregnancy period.It does not increase the occurrence of depression-like behavior of the adult offspring and does not affect the expression of BDNF in hippocampus.