In spite of advances in obstetric care, approximately thirteen million preterm birth occur annually worldwide. Infection is an important and frequent cause of preterm labour and birth using the ascending route from the vagina. Since there are adverse effects from antibiotic use, it is logical to ask do antibiotics given systemically decrease the incidence of preterm birth? A historical review was carried out to assess the numbers and quality of randomised clinical trials. The results confirmed improvement in the number and quality of trials since the sixties.Also, an umbrella review was carried out. Forty five clinical trials were included. The results indicated that the use of antibiotics during pregnancy had no effect in preventing preterm labour before 34 weeks and this is accompanied by an increase in the maternal adverse effects. Antibiotics were also shown to be not effective in preventing neonatal morbidity associated with prematurity. This book should be especially useful to Obstetricians, General Practitioners, young doctors, women in fertile age and researchers in the medical field.