Epidemiology and etiology of preterm delivery

: The causes of the increase in preterm delivery are unknown. A large proportion of very early childbirths are due to infections, with a previous preterm delivery also constituting a strong risk factor. As much as 60% of preterm deliveries are, however, first births, whereby predicting is difficult. Important risk factors also include smoking, diseases of the mother and the fetus as well as the mother's age and social status. Prematurity is more common among blacks. Despite being previously considered safe, loop electrosurgery of the vaginal part of the cervix also predisposes to preterm delivery.