Peri-implantation intercourse does not lower fecundability. Article

Stanford, Joseph B, Hansen, Jared L, Willis, Sydney K et al. (2020). Peri-implantation intercourse does not lower fecundability. . HUMAN REPRODUCTION, 35(9), 2107-2112. 10.1093/humrep/deaa156

cited authors

  • Stanford, Joseph B; Hansen, Jared L; Willis, Sydney K; Hu, Nan; Thomas, Alun



  • Study question

    Does sexual intercourse in the implantation time window (5-9 days after ovulation) reduce fecundability?

    Summary answer

    After adjustment for intercourse in the fecund window and clustering by couple, there was no association between intercourse in the implantation time window and fecundity.

    What is known already

    Previous research has suggested an association between intercourse in the peri-implantation time window (5-9 days after estimated ovulation) and reduced fecundability.

    Study design, size, duration

    We used data from the FERTILI study, a prospective observational study conducted in five European countries, with data collected from 1992 to 1996.

    Participants/materials, setting, methods

    Women who were experienced in fertility awareness tracking kept a daily diary of cervical mucus observations, basal body temperature measurements, coitus and clinically identified pregnancy. We estimated the day of ovulation as cycle length minus 13 days. From 661 women, 2606 cycles had intercourse during the fecund window (from 5 days before to 3 days after the estimated day of ovulation), resulting in 418 pregnancies (conception cycles). An established Bayesian fecundability model was used to estimate the fecundability ratio (FR) of peri-implantation intercourse on fecundability, while adjusting for each partner's age, prior pregnancy, the couple's probability of conception and intercourse pattern(s). We conducted sensitivity analyses estimating ovulation as cycle length minus 12 days, or alternatively, as the peak day of estrogenic cervical mucus.

    Main results and the role of chance

    There was no effect of peri-implantation intercourse on fecundability: adjusted FR for three or more acts of peri-implantation intercourse versus none: 1.00, 95% credible interval: 0.76-1.13. Results were essentially the same with sensitivity analyses. There was an inverse relationship between frequency of intercourse in the fecund window and intercourse in the peri-implantation window.

    Limitations, reasons for caution

    Women with known subfertility were excluded from this study. Many couples in the study were avoiding pregnancy during much of the study, so 61% of otherwise eligible cycles in the database were not at meaningful risk of pregnancy and did not contribute to the analysis. Some couples may not have recorded all intercourse.

    Wider implications of the findings

    We believe the current balance of evidence does not support a recommendation for avoiding intercourse in the peri-implantation period among couples trying to conceive.

    Study funding/competing interest(s)

    No external funding. The authors have no potential competing interests.

    Trial registration number


publication date

  • September 1, 2020

published in


  • Bayes Theorem
  • Coitus
  • Embryo Implantation
  • Europe
  • Female
  • Fertility
  • Humans
  • Pregnancy
  • Time-to-Pregnancy

Digital Object Identifier (DOI)


  • Print

start page

  • 2107

end page

  • 2112


  • 35


  • 9