1. Menon R. Preterm birth: a global burden on maternal and child health. Pathog Glob Health 2012; 106(3): 139-40.
2. Liu L, Oza S, Hogan D, Chu Y, Perin J, Zhu J, et al. Global, regional, and national causes of under-5 mortality in 2000-15: an updated systematic analysis with implications for the Sustainable Development Goals. Lancet 2016; 388(10063): 3027-35.
3. Delnord M, Blondel B, Zeitlin J. What contributes to disparities in the preterm birth rate in European countries? Curr Opin Obstet Gynecol. 2015; 27(2): 133-42.
4. Lantos JD, Lauderdale DS. What is Behind the Rising Rates of Preterm Birth in the United States? Rambam Maimonides Med J 2011; 2(4): e0065.
5. Lee AC, Katz J, Blencowe H, et al. National and regional estimates of term and preterm babies born small for gestational age in 138 low-income and middle-income countries in 2010. Lancet Glob Heal 2013; 1(1): e26-e36.
6. Blencowe H, Cousens S, Chou D, et al. Born too soon: the global epidemiology of 15 million preterm births. Reprod Health 2013; 10(Suppl 1): S2.
7. Steer P, Flint C. ABC of labour care: preterm labour and premature rupture of membranes. BMJ 1999; 318(7190): 1059-1062.
8. Mazaki-Tovi S, Romero R, Kusanovic JP, et al. Recurrent preterm birth. Semin Perinatol 2007; 31(3): 142-58.
9. Liu Y, Wang X, Zou L, Ruan Y, Zhang W. An analysis of variations of indications and maternal-fetal prognosis for caesarean section in a tertiary hospital of Beijing: A population-based retrospective cohort study. Medicine (Baltimore) 2017; 96(7): e5509.
10. van Eerden L, Zeeman GG, Page-Christiaens GCM, et al. Termination of pregnancy for maternal indications at the limits of fetal viability: a retrospective cohort study in the Dutch tertiary care centres. BMJ Open 2014; 4(6): e005145.
11. Kurkinen-Räty M, Koivisto M, Jouppila P. Preterm delivery for maternal or fetal indications: maternal morbidity, neonatal outcome and late sequelae in infants. BJOG 2000; 107(5): 648-655.
12. Reddy UM, Ko C-W, Raju TNK, Willinger M. Delivery indications at late-preterm gestations and infant mortality rates in the United States. Pediatrics 2009; 124(1): 234-40.
13. Varner MW, Esplin MS. Current understanding of genetic factors in preterm birth. BJOG 2005; 112(Suppl 1): 28-31.
14. Esplin MS, Varner MW. Genetic factors in preterm birth-the future. BJOG 2005; 112(Suppl 1): 97-102.
15. D‟Uva M, di Micco P, Strina I, Alviggi C, Iannuzzo M, RanieriA, et al. Hyperhomocysteinemia in women with unexplained sterility or recurrent early pregnancy loss from Southern Italy: a preliminary report. Thromb J 2007; 5: 10.
16. Hwang IW, Kang YD, Kwon BN, Hong JH, Han SH, Kim JS, et al. Genetic variations of MTHFR gene and their association with preterm birth in Korean women. Medicina (Kaunas) 2017; 53(6): 380-5.
17. Nan Y, Li H. MTHFR genetic polymorphism increases the risk of preterm delivery. Int J Clin Exp Pathol 2015; 8(6): 7397-402.
18. Uvuz F, Kilic S, Yilmaz N, Tuncay G, Cakar E, Yuksel B, et al. Relationship between preterm labor and thrombophilic gene polymorphism: A prospective sequential cohort study. Gynecol Obstet Invest 2009; 68(4): 234-8.
19. Gargano JW, Holzman CB, Senagore PK, Reuss ML, Pathak DR, Friderici KH, et al. Polymorphisms in thrombophilia and renin-angiotensin system pathways, preterm delivery, and evidence of placental hemorrhage. Am J Obstet Gynecol 2009; 201(3): 317.e1-9.
20. Du JY, Yang XY, Gong B, Guan YY, Mei LY LY. Relationship of plasma homocysteine levels, folate levels and MTHFR gene polymorphisms with premature delivery. J Sun Yat-Sen Univ (Med Sci) 2013; 34: 894-899 (in Chinese).
21. Nurk E, Tell GS, Refsum H, Ueland PM, Vollset SE. Associations between maternal methylenetetrahydrofolate reductase polymorphisms and adverse outcomes of pregnancy: the Hordaland Homocysteine Study. Am J Med 2004; 117(1): 26-31.
22. Engel SM, Olshan AF, Siega-Riz AM, Savitz DA, Chanock SJ. Polymorphisms in folate metabolizing genes and risk for spontaneous preterm and small-for-gestational age birth. Am J Obstet Gynecol 2006; 195(5): 1231.e1-11.