Abstract: The present study aims to determine levels of IgA, IgG and IgM in HIV sero-negative pregnant subjects, subjects with malaria infection during pregnancy and HIV sero-positive pregnant subjects as compared to healthy HIV sero-negative non-pregnant subjects in Port Harcourt, Nigeria. This is to enable better understanding of the pattern of changes of immunoglobulin concentration in malaria and HIV infection and assist in the antenatal management of these subjects in our environment. A total of 200 female subjects resident in Port-Harcourt, southeastern Nigeria were recruited into the study. These comprised four groupsof 50 female subjects in each group: healthy HIV sero-negative, non-pregnant subjects (group A); healthy HIV sero-negative pregnant subjects (group B); subjects with malaria infection during pregnancy (group C) and HIV sero-positive pregnant subjects (group D). All pregnant subjectswere further divided to the appropriate trimester depending on the duration of their pregnancy. Venous blood samples were obtained and levels of immunoglobulins A, G and M determined with the turbidimetric immunoassay method using an automated chemical analyzer. Significant differences were observed in the values of the various types of immunoglobulins studied between healthy HIV sero-negative non-pregnant (group A) subjects and healthy HIV sero negative pregnant (group B) subjects. Noteworthy is the observation that the values of both IgG and IgM were significantly higher while the values of IgA were significantly lower amongst the nonpregnant subjects in group A, compared to all the other pregnant subject groups: B, C and D (p<0.05). Furthermore, group B subjects were found to have significantly higher values of both IgG and IgM compared to group C subjects but significantly lower values compared to group D subjects (p<0.05). Values of IgA were found to be consistently higher in both group C and D subjects as compared to both group A and group B subjects. During the course of gestation, both group C and D subjects were found to have significantly higher values of IgA compared to group B subjects (p<0.05); whereas group C subjects were found to have significantly lower values of both IgG and IgM compared to group B subjects (p<0.05). Group D subjects were found to have significantly higher values of both IgG and IgM compared to group B subjects (p<0.05). These differences were found to exist despite the duration of gestation. The present study reports that IgG and IgM values were significantly lower and IgA values significant higher in all pregnant subjects compared to HIV seronegative non-pregnant subjects. Furthermore, in subjects with malaria in pregnancy IgG and IgM levels were consistently and significantly low and IgA levels were found to be lowest amongst HIV sero-negative pregnant subjects. Our study describes for the first time the pattern of these changes in immunoglobulin values amongst pregnant subjects of southeastern Nigeria and confirms previous suggestions of an apparent modulation of the immune system by the effects of both pregnancy and malaria infection during pregnancy. We recommend the continual need for adequate checks and enhanced care of these subjects by antenatal care providers in southeastern Nigeria.