Effect of Coital Activity on hastening onset of Labor and Prevention of Postdate Pregnancy

Document Type : Original Article


1 Assistant Professor of Obstetrics & Gynecology, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.

2 Assistant Professor of Pediatric, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.


Introduction: Some physicians believe that sexual intercourse at term will hasten the onset of labor. This study is done to determine whether coital activity hastens the onset of labor and prevents postdate pregnancy.
Methods: This prospective and cross-sectional study enrolled 215 pregnant women (>36wks) of low risk group who referred to obstetric clinic of university hospital of Shahid Sadoughi in Yazd in 2007-2008.In each weekly prenatal visit, the participants were asked about coital activity in previous week. The data of the labor were compared in the women with coital activity (study group) and those who had not (control group).Statistical analysis was done by SPSS (11.5 version), t-test and Chi-square test.
Results: In 105 women, intercourse was done in the last weeks of pregnancy (mean=2.3±0.6 times) and in 110 participants, there was no sexual activity. Coitus at term was accompanied by hastening of labor; less postdate pregnancy and less need for induction of labor. Spontaneous labor occurred in 66.7% of study group and 48.2% of control group. (P<0.05) Postdate delivery beyond 40 week was 7.6% in the study group and 17.3% in the control group that showed a significant decrease. (P<0.05)The incidence of cesarean section, postpartum fever and healthy neonate showed no significant difference in both groups.
Conclusion: Coitus at term can be associated with earlier onset of labor, reduction of postdate pregnancy and reduced requirement for labor induction.


1. Sharami SH, Milani F, Zahiri Z, Mansour­Ghanaei F. A randomized trial of prostaglandin E2 gel and extra­ amniotic saline infusion with high dose oxytocin for cervical ripening. Med Sci Monit 2005 Aug; 11(8):CR
2. van Gemund N, Scherjon S, LeCessie S, van Leeuwen JH, van Roosmalen J, Kanhai HH. A randomized 
trial comparing low dose vaginal misoprostol and dinoprostone  for labour induction. BJOG 2004 
3. Tomlinson AJ, Colliver D, Nelson J, Jackson F. Does sexual intercourse at term influence the onset of
labour? A survey of attitudes of patients and their partners. J Obstet Gynaecol. 1999 Sep;19(5):466­8.
4. Schaffir J. Sexual intercourse at term and onset of labor. Obstet Gynecol 2006 Jun;107(6):1310­4.
5. Tan  P, Yow CM,  Omar SZ. Effect of coital activity on  onset of labor in  women scheduled  for labor
induction: a randomized controlled trial. Obstet Gynecol 2007 Oct;110(4):820­6.
6. Schaffir J. Survey of folk beliefs about induction of labor. Birth 2002 Mar;29(1):47–51.
7. Fox NS, Gelber SE, Chasen ST. Physical and sexual activity during pregnancy are not associated with the  onset of labor and mode of delivery in low risk term nulliparous women. Int J Gynecol Obstet 2007; 8(1).
8. Susman J. Intercourse doesn't hasten onset of labor. J Fam Pract 2006;55(9):757.
9. Petridou  E, Salvanos  H, Skalkidou  A, Dessypris  N, Moustaki M,  Trichopoulos  D. Are  there  common 
triggers of preterm deliveries? BJOG 2001;108:598–604.
10. Sayle AE, Savitz DA, Thorp JM, Hertz­Picciotto I, Wilcox AJ. Sexual activity during late pregnancy and 
risk of preterm delivery. Obstetrics & Gynecology 2001;97:283­289.
11. Tan PC, Andi A, Azmi N, Noraihan MN. Effect of coitus at term on length of gestation, induction of labor, and mode of delivery. Obstet Gynecol 2006;108:134­140.
12. Sayle AE, Savitz DA, Thorp JM Jr, Hertz­Picciotto I, Wilcox AJ.Sexual activity during late pregnancy and 
risk of preterm delivery. Obstet Gynecol 2001;97(2):283­9.
13. Cito G. Sexual activity, cardiotocographic findings and time of delivery in physiologic pregnancy. Survey  of a population controlled by ambulatory cardiotocography. Minerva Ginecol 1997; 49 (12):551­4.
14. Berghella V, Klebanoff M,  McPherson C, Carey JC, Hauth  JC, Ernest JM, et al. Sexual intercourse
association with asymptomatic bacterial vaginosis and Trichomonas vaginalis treatment in relationship to  preterm birth. Am J Obstet Gynecol 2002;187(5):1277­82.