To investigate the values of lymphocyte count (LYM), neutrophil to lymphocyte ratio (NLR), and platelet to lymphocyte ratio (PLR) for diagnosing pre-full term premature rupture of membranes (PPROM) of pregnant women and premature rupture of membranes (PROM) of pregnant women. Methods: 40 pregnant women with PPROM from January 2017 to January 2020 were retrospectively collected in study group 1, 40 pregnant women with PROM in the same period were collected in group study group 2, and 30 full-term pregnant women in the same period were collected in control group. The routine blood testing results, and the rate of group B streptococcus (GBS) infection in vaginal secretions of the women in the three groups were detected. The relationship between the values of LYM, NLR, and PLR of the pregnant women and their rates of GBS infection and premature rupture of membranes was analyzed. Results: There were no significant differences in the incidences of fetal distress, postpartum hemorrhage, placental abruption, intrauterine infection, neonatal asphyxia, neonatal pneumonia, and neonatal pathological jaundice among the three groups (all P>0.05). The incidence of premature delivery (57.5%) of the women in the study group 1 was significant higher than that (32.5%) of the women in the study group 2 and that (3.3%) of the women in the control group (P<0.05). There was no significant difference in YLM value of the women among the three groups (P>0.05). The values of NLR and PLR of the women in the study group 1 were significant higher than those of the women in the study group 2 and the control group (P<0.05). The infection rate of GBS (50.0%) of the women in the study group 1 was significant higher than that (17.5%) of the women in the study group 1 and that (0%) of the women in the control group (P<0.05). Correlation analysis showed there was no correlation between GBS infection of the women and the maternal YLM value (P>0.05), and GBS infection of the women were positively correlated with their NLR and PLR values (P<0.05). ROC curve indicated that NLR and PLR values of the women had good efficacy for diagnosing PPROM and PROM. Conclusion: The values of NLR and PLR of the pregnant women with PPROM or PROM are abnormally elevated, and both of them are positively correlated with the GBS infection of the women, moreover, which both have some clinical value for diagnosing premature rupture of membranes.