Embryo implantation and decidualization are crucial for successful pregnancy

which include multiple genes and signaling pathways

while the precise mechanism regarding embryo implantation and decidualization has yet to be explored. The GABA which activates GABA

A

or GABA

B

receptors has been found playing an important role in early pregnancy. Here we seek to investigate whether GABA

B

receptors participate in embryo implantation in mice. This study first characterized the spatiotemporal expression pattern of GABA

B

receptors in the uterus during the peri-implantation period and found that GABA

B1

expression was drastically upregulated in stromal cells on days 4–6

a period of embryo implantation and early stages of decidualization. Embryo delayed implantation and oil-induced decidualization models were further used to confirm that the GABA

B1

was associated with embryo implantation and decidualization. We also found estrogen or progesterone had no directly effect on expression of GABA

B1

in ovariectomized model. Because we were unable to detect significant GABA

B2

which couples with GABA

B1

to form whole GABA

B

receptors

and the agonist and antagonist of whole GABA

B

receptors had weak effect on the proliferation and differentiation of stromal cells as well

we excluded the possibility whole GABA

B

receptors function

and concluded it should be non-classical signals of GABA

B1

involving in embryo implantation and decidualization. Future studies should focus on investigating the roles and mechanisms of GABA

B1

during embryo implantation and decidualization.