Objectives: Evaluation of the effect of preconception H pylori (HP) infection on the incidence of preeclampsia (PE), gestational diabetes mellitus (GDM) and preterm birth (PTB) in diabetic and non-diabetic women.   
Patients & Methods: 305 pregnant women were eval-uated for body mass index (BMI), presence of diabetes mellitus (DM), and HP infection and estimation of at booking fasting (FBG) and postprandial blood glucose and glycated hemoglobin A1c (HbA1c) and blood pres-sure measures. Women were categorized in two groups: DM and No DM groups, and were subcategorized accord-ing to presence of positive blood for HP IgG as HP+ and HP- subgroups and were followed for devel-opment of complications.    
Results: 117 women had preconception DM and 188 women had no DM; and 132 wom-en were HP+ and 173 were HP- with sig-nificantly (p=0.026) higher incidence of HP infection among diabetic women. Forty-two women of No DM group developed GDM with significantly (p=0.033) higher incidence among HP+. Thirty-seven diabetic women developed poor glycemic control and glu-cosuria with significantly (p=0.0165) high-er incidence among HP+ women. Diabetic HP+ women showed significantly higher HbA1c levels in comparison to diabetic HP- women both at booking time and at the 24th GW. Thirty-six women developed PE with significantly higher frequency of PE among DM than No DM women and among HP+ than HP- women. Twenty women got PTB with significantly higher incidence among HP+ and diabetic women. Statistical analysis defined high at booking FBG, preconception HP infection and BMI as the significant pre-dictors for pregnancy complications.
Conclusion: HP infection with or without DM increased the incidence of PE and PTB. HP infection also increased the incidence of GDM in non-diabetics and aggravates DM in diabetic women.