Preterm Labor: A Review

Introduction: Preterm labor (PTL) is one of the leading causes of perinatal morbidity and mortality. It is one of the major public health problems, especially with reference to mortality, disability and health care expenses.Incidence: The overall incidence of PTL is around 10-15% (6-15% Range)3 (The incidence of PTL in our institute (JNMC) was 10.2% during 2006-2007. Out of all PTL 50% occur spontaneously, 25% following preterm prelabor rupture of membranes (PPROM) and another 25% iatrogenic (Induced due to maternal and/or fetal risks).Risk factors: Previous history of preterm labor is one of the important risk factor(risk of PTL in subsequent pregnancies is 14.3% and 28% after one and two preterm births. Others include multiple pregnancy, uterine over distension (polyhydramnios, macrosomia and fibroids), uterine anomalies, cervical incompetence, bacterial vaginosis, bleeding in early pregnancy, poor socioeconomic status, elderly and adolescent age group and tobacco use.Predictors : Cervical length assessment by USG, fetal fibronectin, vaginal pH are being used.Prevention: Progesterone and clindamycin (abnormal vaginal flora) antibiotic is being used with reasonable evidence.Treatment: Corticosteroids and antibiotics help in reducing neonatal morbidity and mortality and tocolytics (nifedepine and atosiban are recommended) helps in allowing the steroids to act.Newer developments: New predictors like higher vaginal pH (> 4.5) and Gram stain score of 9 to 10 with Nugent criteria in early pregnancy is increasingly associated with preterm labor. Search for selective and safe tocolytic is also under consideration, specially the prostaglandin synthetase inhibitors and the role of potassium channels in myometrium.Conclusion: Successful prediction, prevention and treatment of preterm labor has significant influence on the perinatal outcome, health care expenditure and quality of life. As the cause for preterm labor is still an enigma, it is difficult to predict, prevent and treat PTL successfully. At present the treatment of PTL is mainly antibiotics, tocolytics and corticosteroids with varied success.