Optimal Timing and Frequency of Intercourse for Conception
For couples trying to conceive, have intercourse every 1-2 days starting soon after menstruation ends, or use urinary ovulation predictor kits to detect the LH surge and then have intercourse when detected and continue for 2-3 days. 1, 2
Understanding the Fertile Window
The fertile window is approximately 6 days long, ending on the day of ovulation, with the highest probability of conception occurring on the day before ovulation. 3, 4
- For women with regular cycles (26-32 days), the most fertile days are days 8-19 of the menstrual cycle. 1, 2
- The timing of ovulation varies greatly even among women with regular cycles, making prediction challenging. 1, 2
- Conception probability drops to near zero after ovulation occurs. 3
Two Evidence-Based Approaches
Approach 1: Regular Intercourse Without Ovulation Tracking
Women with regular menstrual cycles should have vaginal intercourse every 1-2 days beginning soon after the menstrual period ends. 1
- This approach ensures coverage of the fertile window without requiring ovulation prediction. 1
- It is straightforward and avoids the stress and cost of ovulation monitoring. 4
Approach 2: Timed Intercourse Using Urinary Ovulation Predictor Kits
Use urinary ovulation predictor kits starting several days before expected ovulation, then have intercourse when the LH surge is detected and continue for 2-3 days. 2
- Urinary ovulation tests detect the LH surge that precedes ovulation by 24-36 hours. 2
- Timed intercourse using urine ovulation tests probably increases the chance of live birth (from 16% to 16-28% per cycle) compared to intercourse without ovulation prediction. 4
- This method also probably increases clinical pregnancy or positive pregnancy test rates (from 18% to 20-28%). 4
Important Caveats About Ovulation Prediction
Accuracy of Self-Estimation
Most women incorrectly estimate their ovulation day. 5
- Only 12.7% of women correctly estimated their ovulation day in one study. 5
- The most common assumption is ovulation on day 14 or 15, but only 55% of estimated ovulation days actually fell within the fertile window. 5
- Only 27% of self-estimated ovulation days corresponded to peak fertility days. 5
Fertility Awareness-Based Methods (FABM)
Evidence is insufficient to recommend fertility awareness-based methods (basal body temperature, cervical mucus monitoring, calendar tracking apps) over other approaches. 4
- We are uncertain whether FABM affects live birth rates, stress levels, or pregnancy outcomes compared to intercourse without ovulation prediction. 4
- The quality of evidence for FABM is very low. 4
Cycle Length Considerations
Regular Cycles (26-32 Days)
- The standard recommendations above apply. 1
- Even with regular cycles, the 6-day fertile window timing varies considerably. 1
Irregular Cycles (<26 or >32 Days)
For women with consistently irregular cycles, ovulation prediction becomes even more critical as the fertile window shifts unpredictably. 2
- Women with cycles shorter than 26 days experience earlier ovulation. 2
- For a 25-day cycle, the fertile period typically falls between days 6-11. 2
- Women with two or more cycles outside the 26-32 day range within one year have higher pregnancy risk with standard day methods. 1
Additional Fertility-Maximizing Recommendations
Beyond timing, couples should be counseled about other factors: 1
- Educate about signs of fertility, including slippery, stretchy cervical mucus during the fertile window. 1
- Discourage smoking, alcohol consumption, and recreational drug use, as these may reduce fertility. 1
- Avoid most commercially available vaginal lubricants, which might reduce fertility. 1
- Note that fertility rates are lower among women who are very thin or obese, and those consuming high levels of caffeine (>5 cups per day). 1
Common Pitfall: Peri-Implantation Intercourse
There is no need to avoid intercourse during the implantation window (5-9 days after ovulation). 6