Caffeine consumption during pregnancy is reported to increase the risk of in utero growth restriction and spontaneous abortion. In the present study, we tested the hypothesis that modest maternal caffeine exposure affects in utero developing embryonic cardiovascular (CV) function and growth without altering maternal hemodynamics. Caffeine (10mg/kg/day subcutaneous) was administered daily to pregnant CD-1 mice from embryonic days (EDs) 9.5 to 18.5 of a 21-day gestation. We assessed maternal and embryonic CV function at baseline and at peak maternal serum caffeine concentration using high-resolution echocardiography on EDs 9.5, 11.5, 13.5, and 18.5. Maternal caffeine exposure did not influence maternal body weight gain, maternal CV function, or embryo resorption. However, crown-rump length and body weight were reduced in maternal caffeine treated embryos by ED 18.5 (P<0.05). At peak maternal serum caffeine concentration, embryonic carotid artery, dorsal aorta, and umbilical artery flows transiently decreased from baseline at ED11.5 (P<0.05). By ED13.5, embryonic aortic and umbilical artery flows were insensitive to the peak maternal caffeine concentration, however, the carotid artery flow remained affected. By ED 18.5, baseline embryonic carotid artery flow increased and descending aortic flow decreased versus non-caffeine exposed embryos. Maternal treatment with the adenosine A_2A receptor inhibitor reproduced the embryonic hemodynamic effects of maternal caffeine exposure. Adenosine A_2A receptor gene expression levels of ED11.5 embryo and ED18.5 uterus were decreased. Results suggest that modest maternal caffeine exposure has adverse effects on developing embryonic CV function and growth, possibly mediated via adenosine A_2A receptor blockade.