1. WHO: recommended definitions, terminology and format for statistical tables related to the perinatal period and use of a new certificate for cause of perinatal deaths. Modifications recommended by FIGO as amended October 14, 1976;Acta Obstet Gynecol Scand,1977
2. The epidemiology, etiology, and costs of preterm birth;Frey;Semin Fetal Neonatal Med,2016
3. Vitamin D and the regulation of placental inflammation;Liu;Reprod Sci,2011
4. The global epidemiology of preterm birth;Vogel;Best Pract Res Clin Obstet Gynaecol,2018
5. Outcomes in preterm infants;Platt;Public Health,2014