Risk of preterm delivery in pregnant women with group B streptococcal urinary infections or urinary antibodies to group B streptococcal and E. coli antigens.

OBJECTIVE

To establish whether there is an association between preterm delivery and either group B streptococcal urinary infection or the presence of urinary antibodies to group B streptococcal or E. coli antigens.

DESIGN

A prospective study with urine culture and antibody measurement performed at the first antenatal visit and at 28 weeks gestation.

SETTING

Ninewells Hospital, Dundee.

SUBJECTS: Two thousand and forty-three women registering consecutively at an antenatal clinic.

MAIN OUTCOME MEASURE: Delivery at less than 37 weeks gestation.

RESULTS

No increase in preterm delivery was observed in women with positive urine cultures for group B streptococci either at booking or at 28 weeks, even when confirmed by positive repeat cultures. Preterm delivery was more common in women with elevated urinary antibodies to E. coli antigens at booking (relative risk 1.81, 95% CI 1.22-2.68, P = 0.005) and at 28 weeks (relative risk 2.36, 95% CI 1.60-3.48, P < 0.0001) and to group B streptococcal antigens at 28 weeks (relative risk 2.24, 95% CI 1.46-3.43, P = 0.0003).

CONCLUSIONS

These data do not support previous reports that positive urine cultures for group B streptococci are associated with an increased risk of preterm delivery. Our report of an association between elevated levels of urinary antibodies and preterm delivery is a new finding consistent with the possibility that a local inflammatory response to uro-genital infection may be important in stimulating the onset of preterm labour. The results suggest that screening for urinary antibodies at 28 weeks gestation might help to identify a group of women at increased risk of prematurity.