Hansen, J. L., Willis, S. K., Hu, N., Thomas, A., & Stanford, J. B. (2020). Peri-implantation intercourse does not lower fecundability. Human Reproduction (Oxford, England), 35(9), 2107-2112. https://doi.org/10.1093/humrep/deaa156
Hansen JL, Willis SK, Hu N, Thomas A, Stanford JB. Peri-implantation intercourse does not lower fecundability. Hum Reprod. 2020;35(9):2107-2112. doi:10.1093/humrep/deaa156
Hansen, J. L., et al. "Peri-implantation intercourse does not lower fecundability." Human Reproduction (Oxford, England), vol. 35, no. 9, 2020, pp. 2107-2112.
Intercourse 5 to 9 days after ovulation did not cut pregnancy chances
A prospective cohort followed 661 women with no known fertility problems. They logged mucus, temperature and intercourse. Intercourse 5 to 9 days after ovulation did not change pregnancy chances in these women. Analysis covered 2606 cycles with intercourse in the fecund window. Three or more such days gave a ratio of 1.00 against none.
Key Findings
The analysis included 2606 cycles from 661 women, with 418 pregnancies (conception cycles).
For three or more days of peri-implantation intercourse versus none, the adjusted fecundability ratio was 1.00 (95% credible interval: 0.76–1.13).
Compared with none, one day of peri-implantation intercourse gave a ratio of 1.00 (0.81, 1.00) and two days gave 1.00 (0.89, 1.08).
Timing ovulation by the mucus peak day (1583 cycles, 526 women) gave a ratio of 0.89 (95% CI, 0.54–1.50) for three or more days.
In the 2606 cycles, 886 (34.0%) had no peri-implantation intercourse. Another 933 (35.8%) had 1 day, 536 (20.6%) had 2 days and 251 (9.6%) had 3 or more days.
Interpretation
Fecundability is the chance of a pregnancy in a given cycle. This cohort study, the FERTILI study, followed women skilled in cycle charting in five European countries. Intercourse 5 to 9 days after ovulation gave the same pregnancy chances as no intercourse in that window. A second way to estimate ovulation day gave similar results. An earlier study of women aged 30 to 44 found a lower ratio for two or more such days. The authors found no single explanation for the difference. The authors note that women with known fertility problems were excluded from the study. The findings support further studies of this timing question, including in couples with fertility problems.
RRM Context
Daily diaries made this question testable. Each woman logged her mucus, temperature and intercourse. Researchers could then compare intercourse timing to ovulation. Restorative reproductive medicine builds on cycle charting. Charted data can answer timing questions like this one.
Our editorial summary of this paper, not the article's abstract.
Abstract
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 Interests
No external funding. The authors have no potential competing interests.
Trial Registration
N/A.
By this author
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