1. Chawanpaiboon S, Vogel JP, Moller AB, Lumbiganon P, Petzold M, Hogan D. Global, regional, and national estimates of levels of preterm birth in 2014: a systematic review and modelling analysis. Lancet Glob Health 2019; 7(1): e37-e46.
2. Walani Salimah R. Global burden of preterm birth. Int J Gynaecol Obstet 2020; 150(1): 31-3.
3. Karlsson O, Kim R. Age distribution of all-cause mortality among children younger than 5 years in low- and middle-income countries. JAMA Netw Open 2022; 5(5): e2212692.
4. Hamilton BE, Martin JA, Ventura SJ. Births: preliminary data for 2005. Health E-Stats. Hyattsville, MD, 2006. Available from: http://www.cdc.gov/nchs/products/ pubs/pubd/hestats/prelimbirths05/ prelimbirths 05.html (accessed July 15, 2007).
5. Khandre V, Potdar J. Preterm birth: an overview. Cureus. 2022; 14(12): e33006.
6. Sharifi N, Khazaeian S. Investigating the Prevalence of Preterm Birth in Iranian Population: A Systematic Review and Meta-Analysis. J Caring Sci. 2017; 6(4): 371–380.
7. Ali Bin Dahman H. Risk factors associated with preterm birth: a retrospective study in Mukalla Maternity and Childhood Hospital, Hadhramout Coast/Yemen. Sudan J Paediatr. 2020; 20(2): 99–110.
8. Shana Green E, Clara Arck P. Pathogenesis of preterm birth: bidirectional inflammation in mother and fetus. Semin Immunopathol 2020; 42(4): 413-29.
9. Norooznezhad AH, Shamshirsaz AA, Hantoushzadeh S. Labor Could Increase Systemic Inflammation and Cause or Deteriorate Cytokine Storm in COVID-19. Iran J Immunol 2022; 19(3): 330-6.
10. Sellersa S, Clark Gray C. Climate Shocks Constrain Human Fertility in Indonesia. World Dev 2019; 117: 357–69.
11. Kassabian S. Building a global policy agenda to prioritize preterm birth: A qualitative analysis on factors shaping global health policymaking. Gates Open Res 2020; 4: 65.
12. Cucinotta D, Vanelli M. WHO Declares COVID-19 a Pandemic. Acta Biomed 2020; 91(1): 157–61.
13. Wen J. Impact of COVID-19 pandemic on birth outcomes: A retrospective cohort study in Nanjing, China. Front Public Health 2022; 10: 923324.
14. Qiao C, Menon R. Preterm birth update in Australasia: A report of the international symposium of Preterm Birth International Collaborative-Australasia branch. Front Pediatr 2022; 10: 903546.
15. Rodriguez K, Nudelman M, Jegatheesan P. Are preterm birth and very low birth weight rates altered in the early COVID (2020) SARS-CoV-2 era? Front Pediatr 2023; 10: 1093371.
16. Andersson-Engelsa S, Andersen PE. Perspectives in Biophotonics: a special issue in honor of the International Graduate Summer School on Biophotonics. J Biomed Opt 2022; 27(5): 050102.
17. Rumea T, Islam D. Environmental effects of COVID-19 pandemic and potential strategies of sustainability. Heliyon 2020; 6(9): e04965.
18. Smith Louisa H, Dollinger CY, VanderWeele TJ, Wyszynski DF, Hernández-Díaz S. Timing and severity of COVID-19 during pregnancy and risk of preterm birth in the International Registry of Coronavirus Exposure in Pregnancy. BMC Pregnancy Childbirth 2022; 22(1): 775.
19. Bobei TI, Haj Hamoud B, Sima RM, Gorecki GP, Poenaru MO, Olaru OG, et al. The Impact of SARS-CoV-2 Infection on Premature Birth—Our Experience as COVID Center. Medicina (Kaunas). 2022; 58(5): 587.
20. Jaberi E, Roksana M. A study on preterm births during 2013-2015, Shiraz, Iran. J Obstet Gynaecol 2018; 38(1): 22-6.
21. Halimi Asl A, Safari S. Epidemiology and Related Risk Factors of Preterm Labor as an obstetrics emergency. Emerg (Tehran) 2017; 5(1): e3.
22. Mohammadi D. Environmental extreme temperature and daily preterm birth in Sabzevar, Iran: a time-series analysis. Environ Health Prev Med 2019; 24(1): 5.
23. Omani-Samani R, Mansournia M. Decomposition of socioeconomic inequalities in preterm deliveries in Tehran, Iran. Int J Gynaecol Obstet 2018; 140(1): 87-92.
24. Nezhadsafar R, Masoumi MTM, Sadeghieh Ahari S. The pattern of seasonal distribution of preterm delivery in Ardabil County [in Persian]. Nursing and Midwifery Journal 2018; 16(1): 38-44.
25. Khojasteh F, Arbabisarjou A, Boryri Tm Safarzadeh A, Pourkahkhaei M. The relationship between maternal employment status and pregnancy outcomes. Glob J Health Sci 2016; 8(9): 53533.
26. Akbari N, Delaram M. Association between maternal weight gain during pregnancy and neonatal birth weight [in Persian]. Journal of Knowledge & Health 2016; 3(2): 39-43.
27. Pak-Niat H, Emam A. Intrauterine fetal death and its associated risk factors in Qazvin Province. In: Proceedings of the 20th Annual Research Congress of Medical Sciences Students of Iran; 2019; Iran. [in Persian].
28. Shoja M, Shoja M, Shoja E, Gharaei M. Prevalence of preterm labor and its associated factors among pregnant women referred to Bent-ol-Hoda Hospital in Bojnurd [in Persian]. North Khorasan Univ Med Sci J 2015; 4: 23.
29. Chehreh R, Karamolahi Z, Aevazi A, Borji M, Saffar A. Prevalence of Preterm Birth Recurrence and Related Factors in Ilam [in Persian]. Iran J Obstet Gynecol Infertil 2018: 21(10): 20-9.
30. Forozanfard F, Mesdaghinia E, Tabasi Z, Sehat M, Totonian S. Prediction of preterm labor based on vaginal pH and cervical length in low risk population during the second trimester of pregnancy [in Persian]. Feyz 2014; 18(3): 260-6.
31. Ajami M, Nik-Khah Shahmirzadi A. Prevalence of preterm labor and its associated factors in Shahroud city [in Persian]. Nasim-e Tondorosti 2013; 2(3): 43-8.
32. Amini L, Mahmoudi Z. Association between structural social determinants of health and pregnancy outcomes: preterm labor and premature rupture of membranes [in Persian]. Sabzevar Univ Med Sci J 2013; 20(1): 109-16.
33. Sehati Shafaei F, Fartash F, Qoujazadeh M, Fardi Azar Z. Maternal outcomes following magnesium sulfate and nifedipine administration in the inhibition of preterm labor [in Persian]. Iran J Obstet Gynecol Infertil 2014; 17(112): 1-6.
34. Soleymani-e- Shayesteh Y, Kamali-Nia Z. The relationship between pregnancy, preterm and premature delivery [in Persian]. J Dent Med-tums 2002; 15(1): 65-72.
35. Rajaei-Fard A, Mohammadbigi A, Mohammadi M, Jolaee H, Alipour H. Risk factors of preterm labor and the effect of education on its prevention [in Persian]. Daneshvar Med 2010; 18(1): 11-8.
36. Neshat R, Majlesi F, Rahimi A, Shariat M, Pourreza A. Association between preterm labor and levels of anxiety, stress, and depression during pregnancy among women attending urban health centers in Dorud [in Persian]. Iran J Obstet Gynecol Infertil 2013; 16(67): 16-24.
37. Ganji T, Einipour Z. Preterm labor and its association with stressful life events during pregnancy [in Persian]. Iran J Nurs 2009; 22(57): 77-86.
38. Sohrabi D, Ghanbari Gorkani M. A survey on Risk factors and outcomes of women with preterm labor admitted to Valieasr hospital in Zanjan [in Persian]. Nursing and Midwifery Journal 2011; 9(2).
39. Afrakhteh M, Ebrahimi S. Prevalence of preterm labor and its associated factors among patients referred to Shohada-e Tajrish Hospital [in Persian]. Pajouhandeh 2002; 7(4): 141-3.
40. Saei M, Mohaddesi H, Edalatnemun R. The predisposing factors of postpartum depression in women referring to selected health centers in Urmia in 2015 [in Persian]. Nursing and Midwifery Journal 2017; 14(11): 918-25.
41. Bobei T, Haj Hamoud B, Sima RM, Gorecki GP, Poenaru MO, Olaru OG, et al. The impact of SARS-CoV-2 infection on premature birth-our experience as COVID center. Medicina (Kaunas) 2022; 58(5): 587.
42. Oakley LL, Örtqvist AK, Kinge J, Vinkel Hansen A, Petersen TG, Söderling J, et al. Preterm birth after the introduction of COVID-19 mitigation measures in Norway, Sweden, and Denmark: a registry-based difference-in-differences study. Am J Obstet Gynecol 2022; 226(4): 550.e1-550.e22.
43. Mullin AM, Handley SC, Lundsberg L, Elovitz MA, Lorch SA, McComb EJ, et al. Changes in preterm birth during the COVID-19 pandemic by duration of exposure and race and ethnicity. J Perinatol 2022; 42(10): 1346-52.
44. Margerison-Zilko CE, Strutz KL, Li Y, Holzman C. Stressors across the life-course and preterm delivery: evidence from a pregnancy cohort. Matern Child Health J 2017; 21(3): 648-58.
45. Fell DB, Dimanlig-Cruz S, Regan AK, Håberg SE, Gravel CA, Oakley L, et al. Risk of preterm birth, small for gestational age at birth, and stillbirth after covid-19 vaccination during pregnancy: population based retrospective cohort study. BMJ 2022: 378: e071416.
46. Darling AM, Shephard H, Nestoridi E, Manning SE, Yazdy MM. SARS-CoV-2 infection during pregnancy and preterm birth in Massachusetts from March 2020 through March 2021. Paediatr Perinat Epidemiol 2023; 37(2): 93-103.
47. Smith EF, Hemy NR, Hall GL, Wilson AC, Murray CP, Simpson SJ. Risk factors for poorer respiratory outcomes in adolescents and young adults born preterm. Thorax 2023; 78(12): 1223-32.
48. Karasek D, Baer RJ, McLemore MR, Bell AJ, Blebu BE, Casey JA, et al. The association of COVID-19 infection in pregnancy with preterm birth: A retrospective cohort study in California. Lancet Reg Health Am 2021; 2: 100027.
49. Wood SL, Tang S, Crawford S. Cesarean delivery in the second stage of labor and the risk of subsequent premature birth. Am J Obstet Gynecol 2017; 217(1): 63. e1-63. e10.
50. Huseynova R, Bin Mahmoud L, Abdelrahim A, Al Hemaid M, Almuhaini MS, Jaganath PP. Prevalence of Preterm Birth Rate During COVID-19 Lockdown in a Tertiary Care Hospital, Riyadh. Cureus 2021; 13(3): e13634.
51. Shah S, Desai S, Desai T, Szkwarko D, Desai G. Trends and risk factors in tribal vs nontribal preterm deliveries in Gujarat, India. AJOG Glob Rep 2021; 4(1): 100026.
52. Harvey EM, McNeer E, McDonald MF, Shapiro-Mendoza CK, Dupont WD, Barfield W, et al. Association of preterm birth rate with COVID-19 statewide stay-at-home orders in tennessee. JAMA Pediatr 2021; 175(6): 635-7.
53. Martinez-Perez O, Rodriguez PP, Hernandez MM, Encinas Pardilla MB, Perez NP, Vila Hernandez MR, et al. The association between SARS-CoV-2 infection and preterm delivery: a prospective study with a multivariable analysis. BMC Pregnancy Childbirth 2021; 21(1): 273.
54. Berghella V, Saccone G. Cervical assessment by ultrasound for preventing preterm delivery. Cochrane Database Syst Rev 2019; 9(9): CD007235.
55. Been JV, Burgos Ochoa L, Bertens LCM, Schoenmakers S, Steegers EAP, Reiss IKM. Impact of COVID-19 mitigation measures on the incidence of preterm birth: a national quasi-experimental study. Lancet Public Health 2020; 5(11): e604–e611.
56. Hedermann G, Hedley PL, Bækvad-Hansen M, Hjalgrim H, Rostgaard K, Poorisrisak P, et al. Danish premature birth rates during the COVID-19 lockdown. Arch Dis Child Fetal Neonatal Ed 2021; 106(1): 93-5.
57. Yang J, Baer RJ, Berghella V, Chambers C, Chung P, Coker T, et al. Recurrence of Preterm Birth and Early Term Birth. Obstet Gynecol. 2016; 128(2): 364-72.
58. de Souza Silva GA, da Silva SP, da Costa MAS, da Silva AR, de Vasconcelos Alves RR, das Chagas Ângelo Mendes Tenório F, et al. SARS-CoV, MERS-CoV and SARS-CoV-2 infections in pregnancy and fetal development. J Gynecol Obstet Hum Reprod 2020; 49(10): 101846.
59. Ali Ashraf M, Keshavarz P, Hosseinpour P, Erfani A, Roshanshad A, Pourdast A, et al. Coronavirus Disease 2019 (COVID-19): A systematic review of pregnancy and the possibility of vertical transmission. J Reprod Infertil 2020; 21(3): 157-68.
60. Creswell L, Rolnik DL, Lindow SW, O’Gorman N. Preterm Birth: Screening and Prediction. Int J Womens Health 2023; 15: 1981-97.
61. Arboleya S, Rios-Covian D, Maillard F, Langella P, Gueimonde M, Martín R. Preterm Delivery: Microbial Dysbiosis, Gut Inflammation and Hyperpermeability. Front Microbiol 2021; 12: 806338.
62. Brown J, Chang X, Matson A, Lainwala S, Chen MH, Cong X, et al. Health disparities in preterm births. Front Public Health. 2023; 11: 1275776.
63. Mohammad Jafari R, Zargar M, Barati M, Ershadian S. The comparison of predictive value of cervical length in singleton spontaneous preterm labor with in vitro fertilization pregnancies: A cohort study. Int J Reprod Biomed 2021; 19(1): 57-62.
64. Phillips C, Velji Z, Hanly C, Metcalfe A. Risk of recurrent spontaneous preterm birth: a systematic review and meta-analysis. BMJ Open 2017; 7(6): e015402.
65. Cristina Melo E, de Oliveira RR, de Freitas Mathias TA. Factors associated with the quality of prenatal care: an approach to premature birth. Rev Esc Enferm USP 2015; 49(4): 540-9.
66. Lassi ZS, Ana A, Das JK, Salam RA, Padhani ZA, Irfan O, et al. A systematic review and meta-analysis of data on pregnant women with confirmed COVID19: Clinical presentation, and pregnancy and perinatal outcomes based on COVID-19 severity. J Glob Health 2021: 11: 05018.
