الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Preterm birth (PTB) refers to a delivery that occurs between 20 and 37 weeks of gestation due to presence of uterine contractions of sufficient frequency and intensity to effect progressive effacement and dilation of the cervix prior to term gestation (a delivery before 20 weeks is a miscarriage in the United States, although the upper gestational age threshold for miscarriage varies worldwide i.e. 28 weeks in the developing countries). (2)
Many risk factors for preterm labour have been identified .The most widely recognized of these include history of spontaneous preterm birth, history of indicated preterm birth, history of abortion , genetic factors, non-hispanic black race,advanced maternal age , cervical surgery, uterine malformations, chronic medical disorders, previous infant with sudden infant death syndrome, assisted reproduction, vaginal bleeding in early pregnancy and infection.Additional risk factors are periodontal disease and genital tract infection/colonization.
The diagnosis of preterm labor based upon clinical criteria of regular painful uterine contractions accompanied by cervical change (dilation and/or effacement). Vaginal bleeding and/or ruptured membranes in this setting increase diagnostic certainty. Because the clinical findings of early labor are poorly predictive of the diagnosis, over-diagnosis is common until labor is well established.