The relationship between prematurely ruptured membranes and fetal immunoglobulin production.

Cord blood and maternal sera were studied in a series of 227 cases of prematurely ruptured membranes (PRM) with respect to: (1) fetal immunoglobulin (lg) synthesis associated with PRM, (2) the interrelationship between different lg classes during infection, and (3) the relationship between lg values and the duration of PRM prior to the onset of labor. A preliminary report from this laboratory, which indicated that a humorla fetal immune response occurred in some but not all cases of PRM, and that significant increases in either IgA or IgM could be found, was confirmed. There was both clinical and immunologic evidence of one peak of infection one to 12 hours after onset of PRM and another after 72 hours after onset of PRM, suggesting that some patients were infected before the clinical onset of PRM symptomatology. Increased IgA and/or IgM was found in 16.3% of infants with clinical evidence of infection. This was comparable to the 18.5% of patients with PRM who had elevated IgA and/or IgM without clinical evidence of infection. Further, there was no correlation between the severity of infection and the presence of lg elevation. Based on the data in the present series, lg determination in cord blood cannot be used to distinguish cases of PRM with and without fetal infection.