The Royal College of Obstetricians and Gynaecologists RCOG have released updated guidelines on prevention of early onset neonatal group B streptococcal GBS infection which were published online September 13 2017 in the British Journal of Obstetrics and Gynecology. The guidelines do not recommend universal bacteriological screening. And if performed bacteriological testing should ideally be carried out at 35 37 weeks of gestation or 3 5 weeks prior to the anticipated delivery date e.g. 32 34 weeks of gestation for women with twins.