Relationship between group B Streptococcal rectovaginal colonization and Vitamin D deficiency in pregnant women

Vitamin D has been recognized to have a significant impact on modulating immune response in the host body. The relationship between deficiency of Vitamin D and rectovaginal colonization with Group B Streptococcus (GBS) in pregnant women is still not well understood.

To determine the influence of Vitamin D deficiency on the rectovaginal colonization with Group B Streptococcus amongst pregnant women. The authors hypothesized that decreased level of Vitamin D in serum could be a significant risk factor for colonization with GBS in the last trimester of pregnancy.

The data for the maternal Vitamin D serum levels, an umbilical cord blood Vitamin D levels, maternal GBS status and mother's compliance to Vitamin D were collected and examined retrospectively for 795 pregnant women between November 2017 and May 2018. Additional comparators (demographic characteristics, ethnicity, pre-pregnancy obesity etc.) were included in the study.

Overall, 17.5% women (n = 139/795) were GBS positive in their third trimester rectovaginal swabs. Vitamin D deficiency group in early pregnancy had significantly higher number of women with GBS positive culture [85/396 (21%) vs. 54/399 (13%), p = 0.004]. GBS positive women had lower cord Vitamin D levels in comparison to GBS negative women (p = 0.016). Women compliant with their Vitamin D intake had significantly lower GBS positive rates [36/169 (18%) vs. 47/130 (27%), p = 0.030].

The study supported our hypothesis that low Vitamin D levels in maternal serum and cord blood are strongly associated with increased risk of GBS colonization in pregnancy. Further studies are warranted to examine this association and interventional potential of Vitamin D in reducing or preventing GBS colonization in pregnancy.