Investigating the Cause of Unwanted Pregnancies in Oral Contraceptive Pills Users Referred to Health Centers of Mashhad, Iran in 2008

Document Type : Original Article


1 Lecturer, Department of Midwifery, Evidence Based Research Center, School of Nursing and Midwifery, Mashhad University of Medical Sciences, Mashhad, Iran.

2 Lecturer, Department of Midwifery, Islamic Azad University of Quchan, Quchan, Iran.


Introduction: Although the failure rate of oral contraceptive pills is 2-3%, the women experienced 7% failure rate at first year of use of oral contraceptive pills. Because of 9-17.2% of women in reproductive age in Mashhad, Iran consumed oral contraceptive pills to prevent pregnancy, this study was conducted to assign the cause of unwanted pregnancies in oral contraceptive pills users.
Methods: This case-control study was conducted on 72 women referred to family health unit of medical health centers of Mashhad, Iran in 2008. We selected the women who had taken oral contraceptive pills in 2008 as case group. Data were obtained by interview forms and analyzed with SPSS software version 14.5, t-test, chi-square, Fisher exact test and Mann-Whitney tests by the confidence of 95%.
Results: There was no statistically significant difference in demographic characteristics and other distracted variables (p>0.05). According to regular consumption of pills, there was a statistically significant difference between two groups (p<0.001). The most common cause of irregular consumption in women with unwanted pregnancy (63.3%) was missing pills. Two groups had significant differences regarding having knowledge about missed pill guidelines (p= 0.024) and concomitant use of antibiotics (p= 0.033); as 14 women (38.9%) of unwanted pregnancy group and 6 women (16.7%) of non-pregnant group used both antibiotics and oral contraceptive pills simultaneously.
Conclusion: The most frequent cause of failure of oral contraceptive pills was irregular consumption and antibiotics interactions and missed pills.


  1. Hoseini M. [Population and family planning]. Tehran:Boshra Publisher;2001:32. [in Persian].
  2. Jarahi L, Erfanian M, Seyyed nouzadi M, Maslahati A. Assessment of reproductive behavior and women s compatibility in unwanted pregnancy in mashhad. Journal ofFundamentals of mental health 2012;14(1)16-23.
  3. vak O, Unsal atan S, Saruhan A, Sevil U.Preventing and Terminating Unwanted Pregnancies in Turkey. Journal of Nursing Scholarship 2006; 38(1): 6-10.
  4. Kavlak O, Atan SU, Saruhan A, Sevil U. Preventing and terminating unwanted pregnancies in Turkey. J Nurs Scholarsh 2006;38(1)6-10.
  5. Kabir SM. Causes and consequences of unwanted pregnancy from Asian women's perspectives. Suppl Int J Gynecol Obstet 1989;3:9-14.
  6. Christensen AL, Stuart EA, Perry DF, Le HN. Unintended pregnancy and perinatal depression trajectories in low-income, high-risk hispanic immigrants. Prev Sci 2011 Sep;12(3):289-99.
  7. Azizi A, Amirian F, Pashaei T, Amirian M. [Prevalence of unwanted pregnancy and its association with health[1]related quality of life in pregnant women city Salas city, Kermanshah, Iran, 2007] [Article in Persian]. J Obstet Gynecol Infertil 2011;14(5):24-9.
  8. Sable MR, Wilkinson DS. Pregnancy wantedness and adverse pregnancy outcomes: Differences by race and Medical status. Fam Plann Prespect 1997;29(2):76-81.
  9. Cunningham FG, Leveno KJ, Bloom SL, Hauth JC, Gilstrap III L, Wenstrom KD. Williams obstetrics. New York:McGraw-Hill;2005:841-72.
  10. Speroff L, Fritz MA. Clinical gynecologic endocrinology and infertility. 7 th ed. Philadelphia:Lippincott Williams & Wilkins;2005:735-809.
  11. Foster DG , Bley J , Mikanda J, Induni M, Arons A, Baumrind N, et al. Contraceptive use and risk of unintended pregnancy in California. Contraception 2004 Jul;70(1):31-9.
  12. Mousavifar N, Hafizi L, Hami A. [Determining the rate of oral contraceptive pills failure in unintended pregnancies] [Article in Persian]. ]. Iran J Obstet Gynecol Infertil 2011 Jun -Jul;14(2):1-6.
  13. .Robabi H, Sarani H, Azarkish F, Dastfan Z, Dashipoor A. [The survey of factors associated with unwanted pregnancy among women referring to health centers of Iranshahr in 2007] [Article in Persian]. Iran J Obstet Gynecol Infertil 2011 Oct-Nover;14(4):32-40.
  14. . Paul F, Brenner DR. Mishell JR. In: Scott JR, Gibbs RS, Karlan BY, Haney AF. Danforth's obstetrics and gynecology. 9th ed. Philadelphia:Lippincott Williams & Wilkins;2003: 709-728
  15. van Bogaert LJ. 'Failed' contraception in a rural South African population. S AFr Med J 2003 Nov;93(11):858- 61
  16. Amin Shokravi F, Filipa H Ch. Contraceptive failure and continuation rates. JOURNAL OF REPRODUCTION AND INFERTILITY.2005. jul 5(19):249-258.
  17. Sharifiyan Attar J. [Knowledge, attitude and practice of contraception in health centers in Mashhad] [Thesis in Persian]. Mashhad:School of Nursing and Midwifery, Mashhad University of Medical Sciences and Health Services;1997.
  18. Garcia F, Hatch KD, Berek JS. Intraepithelial disease of the cervix, vagina, and vulva. In: Berek JS, Berek DL. Berek & Novak's gynecology. 15th ed. Philadelphia:Lippincott Williams & Wilkins;2012:574-618.
  19. Cheng Y, Zhu W, Li Z, Zhang Y, Wang A. Contraceptive practices of women requesting termination of pregnancy: a study from China. Contraception 1997 Jan;55(1):15-7.
  20. Kovacs GT, Riddoch G, Duncombe P, Welberry L, Chick P, Weisberg E, et al. Inadvertent pregnancies in oral contraceptive users.Med J Aust 1989 May 15 ;150(10):549-51
  21. Barjot P , Graesslin O , Cohen D, Vailant P, Clerson P, Hoffet M. [Pregnancies occurring during oral contraception: lessons from the GRECO studt] [Article in French] .Gynecol Obstet Fertil 2006 Feb;34(2):120-6
  22. Sparrow MJ. Pill method failures in women seeking abortion: fourteen years experience. N Z Med J 1998 Oct 9;111(1075):386-8.
  23. Toh S, Mitchell AA, Anderka M, de Jong-van den Berg LT, Hernández-Díaz S; National Birth Defects Prevention Study. Antibiotics and oral contraceptive failure - a case-crossover study. Contraception 2011 May;83(5):418-25.
  24. Hansen TH , Lundvall F. Factors influencing the reliability of oral contraceptives . Acta Obstet Gynecol Scand 1997 Jan;76(1):61-4.
  25. Khan MA. Factors associated with oral contraceptive discontinuation inrural Bangladesh. Healthy Policy Plan 2003 Mar;18(1):101-8.
  26. Moos MK, Bartholomew NE, Lohr KN. Counseling in the clinical setting to prevent unintended pregnancy: an evidence-based research agenda. Contraception 2003 Feb;67(2):115-32.
  27. Omo-Aghoja LO, Omo-Aghoja VW, Okonofua FE, Aghedo O, Umueri C, Otayohwo R, et al. Perceptions and attitudes of a rural community to abortion in the Niger-delta region of Nigeria. Niger J Clin Pract 2009 Dec;12(4):443-9