Early life stress in gestation may result in an increased vulnerability to disease and behavior alteration in offspring. The fetus may often experience intermittent intrauterine hypoxia stress under a variety of conditions, such as pregnancy at high altitude, pregnancy with anemia, cord compression, hypertension, obstructive sleep apnea and preeclampsia. The mechanism regarding the fetal antecedents contributing to disease development remains limited. Here we reported that maternal gestational intermittent hypoxia (GIH) induced by hypobaric high-altitude hypoxia of 5km (equivalent to ~10.8% O2 at sea level), 4 hour / day for 21 days caused a sex-dependent anxiety-like behavior in 90-day-old (P90) male offspring but not female offspring analyzed by open-field test, light-dark box test and elevated plus maze test (n=10, p<0.05). The CRHR1 mRNA expression in PVN and central amygdala (CeA) of P90 (n=8) and in hypothalamus of embryonic day 19 (E19) (n=7) were tested by quantitative real-time PCR. We found that there was a significant increase of CRHR1 mRNA expression in male’s PVN (p<0.05) but not in female’s at the age of P90. No difference of CRHR1 mRNA expression was found in CeA of P90 offspring. GIH also induced an increased CRHR1 mRNA in the hypothalamus at the E19 (p<0.05). There were two CpG (island-1 and -2) within the Crhr1 gene promoter by the software analysis, and we demonstrated the island-1 between -607 and -502 bp functioned as the major regulatory domain of Crhr1 transcription activity, and found that the demethylation at the CpG sites of Crhr1 promoter enhanced CRHR1 mRNA expression in vitro (n=3, p<0.001). Furthermore, in vivo, the increase of CRHR1 mRNA expression might be modulated by the decreased methylation at -535 CpG sites within the island-1 occurred in male E19 embryo (n=7, p<0.05) and the other in CpG three sites, such as -587 (p<0.01), -547 (p<0.05) and -544 (p<0.01) in the PVN of P90 male offspring (n=10), which might come from a decreased expression of DNMT3b in male offspring after GIH (n=7, p<0.05). In conclusion, GIH induces anxiety-like behavior in male adult offspring, which associated with the sex-dependent expression of CRHR1 mRNA in the PVN but not in the CeA in offspring. GIH can alter Crhr1 gene methylation, principally via DNMT3b, and Crhr1 demethylation is associated with high-expressed CRHR1 mRNA, suggesting a sex-biased mechanism for Crhr1 gene expression associated with the anxiety-like behavior in GIH adult offspring. Our findings suggest that the vulnerability to hypoxia-induced anxiety in offspring occurs through the sexually differential epigenetic modification of Crhr1 genomic regions. We address a novel hypothesis, that GIH-induced male-sexdependent demethylation at CpG sites of Crhr1 DNA in promoter triggers elevation of CRHR1 mRNA in PVN and anxiety-like behavior in adult offspring.