Background: Pregnancy has been known to increase susceptibility to gingival inflammation. Epidemiological studies have shown that the prevalence of gingivitis increases in pregnant women when compared to non-pregnant women. New evidence supports an association between the gingival health status and increased serum levels of female sex hormones during pregnancy. Aim: The aim of the present study is to assess therelationship between serum levels of estrogen and progesterone in relation to its possible effect on gingival tissue health throughout pregnancy period. Patients and Methods: This study was conducted on 40 selected women with age range 20-35 years, diagnosed as having gingival inflammation. 30 of them were pregnant and the other 10 were non pregnant and were selected as controls. Blood sample from each woman was obtained at baseline to determine the serum levels of estrogen and progesterone. Gingival inflammation was assessed by gingival index (GI) and by bleeding on probing (BOP) and it was correlated with estrogen and progesterone serum levels in both pregnant and non-pregnant groups. Clinical parameters (GI, BOP and PI) were recorded. Comparisons between both groups as a regard to these clinical parameters were done. Results: Our data confirm that gingival tissues are more susceptible to inflammation during pregnancy. Gingival index (GI) and bleeding on probing (BOP) increased throughout pregnancy period when compared with the control group with statistically significant differences (p < 0.05) with peak level at third trimester. Dental plaque did not increase in relation to gingival inflammation during the course of pregnancy. Our results also, revealed that (GI) and (BOP) had strong positive correlation with changes in estrogen and progesterone serum levels with statistically significant difference (p < 0.05), while the plaque index (PI) Showed no correlation. Conclusions:pregnancy gingivitis has direct correlation with the increase of serum levels of estrogen and progesterone hormones. Bacterial plaque is important for the initiation   of gingival inflammation during pregnancy. Therefore, the maintenance of oral hygiene before and during pregnancy is very important in order to reduce the incidence and the severity of gingival inflammation and preserve gingival tissue health during pregnancy period.