Inter-Pregnancy Interval and the Incidence of Preterm Birth

  • Maryam Asgharnia Reproductive Health Research Center, Guilan University of Medical Sciences, Rasht, Iran
  • Tahereh Varasteh Mail Reproductive Health Research Center, Guilan University of Medical Sciences, Rasht, Iran
  • Davoud Pourmarzi School of Public Health, Faculty of Medicine, The University of Queensland, Brisbane, Australia
Inter-Pregnancy Interval, Preterm Birth, Preeclampsia, Gravidity


Objective: Preterm birth is associated with high rates of neonatal morbidity and mortality. This study aimed to investigate the relationship between inter-pregnancy interval and the incidence of preterm birth.
Materials and methods: In a case-control study, 185 women with preterm delivery and 185 women with term delivery were included. Data including inter-pregnancy interval, demographic characteristics, history of prenatal and neonatal complications, parity, gravidity, type of delivery, and smoking status were collected.
Results: The mean of the inter-pregnancy interval in the case and control groups were 79.84 ± 45.55 months and 78.49 ± 41.29 months, respectively (P = 0.767). Inter-pregnancy interval 12-month or less in comparison with Inter-pregnancy interval more than 24 months significantly increased the odds of preterm delivery (OR: 4.05, 95% CI: 1.06-15.39, p = 0.040). However, inter-pregnancy interval of 13-24 months was not a risk factor when compared with more than 24-month inter-pregnancy interval (OR: 1.54, 95% CI: 0.62-3.80, p = 0.351). Having an educational level less than high school in comparison with tertiary level decreased the odds of preterm delivery (OR: 0.25, 95% CI: 0.11-0.56, P = 0.040). With each increase in number of gravidity odds of preterm delivery increased by 1.5 times (95% CI: 1.11-2.04, P = 0.009). Having a history of preterm delivery (OR: 2.57, 95% CI: 1.17-5.64, P = 0.019) and experiencing preeclampsia (OR: 1.98, 95% CI: 1.06-3.68, P = 0.032) increased the odds of preterm delivery.
Conclusion: Inter-pregnancy interval of 12-month or less in comparison with more than 2-year inter-pregnancy interval, experiencing preeclampsia, history of preterm delivery and increased number of gravidity increase the risk of preterm delivery. Health care providers need to be informed with the appropriate inter-pregnancy interval and counsel women to make an informed decision regarding their pregnancy.


1. World Health Organization. Preterm birth, Fact sheet: World Health Organization: 2018. Available from:
2. Liu L, Oza S, Hogan D, Perin J, Rudan I, Lawn JE, et al. Global, regional, and national causes of child mortality in 2000–13, with projections to inform
post-2015 priorities: an updated systematic analysis. Lancet 2015; 385: 430-40.
3. Vogel JP, Chawanpaiboon S, Moller A-B, Watananirun K, Bonet M, Lumbiganon P. The global epidemiology of preterm birth. Best Pract Res Clin Obstet Gynaecol 2018; 52: 3-12.
4. Beck S, Wojdyla D, Say L, Betran AP, Merialdi M, Requejo JH, et al. The worldwide incidence of preterm birth: a systematic review of maternal mortality and morbidity. Bull World Health Organ 2010; 88: 31-8.
5. Vakilian K, Ranjbaran M, Khorsandi M, Sharafkhani N, Khodadost M. Prevalence of preterm labor in Iran: a systematic review and meta-analysis. Int J Reprod Biomed (Yazd) 2015; 13: 743-8.
6. DeFranco EA, Stamilio DM, Boslaugh SE, Gross GA, Muglia LJ. A short interpregnancy interval is a risk factor for preterm birth and its recurrence. Am J Obstet Gynecol 2007; 197: 264.e1-6.
7. Wendt A, Gibbs CM, Peters S, Hogue CJ. Impact of increasing inter‐pregnancy interval on maternal and infant health. Paediatr Perinat Epidemiol 2012; 26: 239-58.
8. Ball SJ, Pereira G, Jacoby P, De Klerk N, Stanley FJ. Re-evaluation of link between interpregnancy interval and adverse birth outcomes: retrospective cohort
study matching two intervals per mother. BMJ 2014; 349: g4333.
9. Smits LJ, Elzenga HM, Gemke RJ, Hornstra G, van Eijsden M. The association between interpregnancy interval and birth weight: what is the role of maternal polyunsaturated fatty acid status? BMC pregnancy childbirth 2013; 13: 23.
10. Zhu BP. Effect of interpregnancy interval on birth outcomes: findings from three recent US studies. Int J Gynaecol Obstet 2005; 89 Suppl 1: S25-33.
11. Howard EJ, Harville E, Kissinger P, Xiong X. The association between short interpregnancy interval and preterm birth in Louisiana: a comparison of methods. Matern Child Health J 2013; 17: 933-9.
12. Grisaru-Granovsky S, Gordon ES, Haklai Z, Samueloff A, Schimmel MM. Effect of interpregnancy interval on adverse perinatal outcomes-a national study.
Contraception 2009; 80: 512-8.
13. Simonsen S, Lyon JL, Stanford JB, Porucznik CA, Esplin MS, Varner MW. Risk factors for recurrent preterm birth in multiparous Utah women: a historical cohort study. BJOG 2013; 120: 863-72.
14. Miller JE. Birth intervals and perinatal health: an investigation of three hypotheses. Fam Plann Perspect 1991; 23: 62-70.
15. Zhu BP, Rolfs RT, Nangle BE, Horan JM. Effect of the interval between pregnancies on perinatal outcomes. N Engl J Med 1999; 340: 589-94.
16. van den Broek NR, Jean-Baptiste R, Neilson JP. Factors associated with preterm, early preterm and late preterm birth in Malawi. PloS one 2014; 9: e90128.
17. do Carmo Leal M, Esteves-Pereira AP, Nakamura-Pereira M, Torres JA, Theme-Filha M, Domingues RMSM, et al. Prevalence and risk factors related to preterm birth in Brazil. Reproductive health 2016; 13: 127.
18. Alijahan R, Hazrati S, Mirzarahimi M, Pourfarzi F, Hadi PA. Prevalence and risk factors associated with preterm birth in Ardabil, Iran. Iran J Reprod Med 2014; 12: 47-56.
19. Sharma D, Shastri S, Sharma P. Intrauterine growth restriction: antenatal and postnatal aspects. Clin Med Insights Pediatr 2016; 10: 67-83.
20. Ruiz M, Goldblatt P, Morrison J, Kukla L, Švancara J, Riitta-Järvelin M, et al. Mother's education and the risk of preterm and small for gestational age birth: a DRIVERS meta-analysis of 12 J Epidemiol Community Health 2015; 69: 826-33.
21. Ghose ST, Samal S, Armugam S, Parida P. Measurement of cervical biometry using transvaginal ultrasonography in predicting preterm labor. J Nat Sci Biol Med 2014; 5: 369-72.
22. Ahankari A, Bapat S, Myles P, Fogarty A, Tata L. Factors associated with preterm delivery and low birth weight: a study from rural Maharashtra, India. F1000Res 2017; 6: 72.
23. Wang H, Hu YF, Hao JH, Chen YH, Wang Y, Zhu P, et al. Maternal serum zinc concentration during pregnancy is inversely associated with risk of preterm birth in a Chinese population. J Nutr 2016; 146: 509-15.
How to Cite
Asgharnia M, Varasteh T, Pourmarzi D. Inter-Pregnancy Interval and the Incidence of Preterm Birth. J Fam Reprod Health. 14(1):52-56.
Original Articles