Relationship between cord blood vitamin D level and group B Streptococcus vaginal carriage rate in pregnant women

SummaryBackground & aimsGroup B streptococci (GBS) are a major cause of neonatal infection. The existence of a link between levels of vitamin D and vaginal carriage of GBS was investigated.MethodsVitamin D level, assayed from umbilical venous blood at birth, and the status of GBS vaginal carriage during the last term of pregnancy were available from 2246 mother–child couples.ResultsLevels of vitamin D in cord blood at birth was deficient (<10 ng/ml), insufficient (10 to 30 ng/ml), or normal (>30 ng/ml) in 32.1%, 53.0% and 14.9% of tested subjects, respectively. Levels differed significantly depending on the season of delivery, the duration of exposure to sunlight, the skin phototype, and on vitamin D supplementation. The percentage of GBS vaginal carriage was 15.4. A negative association was observed between GBS vaginal carriage and level of vitamin D (P < 0.01 by chi-square test). No relationship was established between GBS colonisation (27 cases identified) or infection (7 cases identified) and vitamin D status.ConclusionsA correct vitamin D level was associated with a lower rate of GBS vaginal carriage during pregnancy. This calls for the monitoring of vitamin D status in pregnant women, a screen which could greatly reduce the need for intrapartum antibiotic prophylaxis.