Evidence-based prenatal care: part II. Third-trimester care and prevention of infectious diseases.

All pregnant women should be offered screening for asymptomatic bacteriuria, syphilis, rubella, and hepatitis B and human immunodeficiency virus infection early in pregnancy. Women at increased risk should be tested for hepatitis C infection, gonorrhea, and chlamydia. All women should be questioned about their history of chickenpox and genital or orolabial herpes. Routine screening for bacterial vaginosis is not recommended. Influenza vaccination is recommended in women who will be in their second or third trimester of pregnancy during flu season. Women should be offered vaginorectal culture screening for group B streptococcal infection at 35 to 37 weeks' gestation. Colonized women and women with a history of group B streptococcal bacteriuria should be offered intrapartum intravenous antibiotics. Screening for gestational diabetes remains controversial. Women should be offered labor induction after 41 weeks' gestation.