Timing Intercourse After PDG Rise for Conception
Your reproductive endocrinologist's recommendation to have intercourse a day after the PDG (pregnanediol-3-glucuronide) rise is actually counterproductive for conception, as ovulation has already occurred by that time and the fertile window has closed.
Understanding the Timing Problem
The fundamental issue is that PDG rises AFTER ovulation has already happened, not before:
- Urinary PDG increases 24-48 hours after ovulation occurs, rising in parallel with serum progesterone from the corpus luteum 1
- Studies using ultrasound-confirmed ovulation demonstrate that PDG rises a median of 0.81 days after ovulation, with the peak occurring approximately 7.5 days post-ovulation 2
- The PDG rise confirms that ovulation already occurred, but does not predict when it will happen 3, 4
Why This Timing Misses the Fertile Window
Sperm must be present BEFORE ovulation occurs to maximize conception chances:
- The optimal fertile window is the 6 days leading up to and including ovulation day, with the highest pregnancy rates occurring when intercourse happens 1-2 days before ovulation 5
- Sperm can survive in the female reproductive tract for up to 5 days, but the egg is only viable for 12-24 hours after ovulation 5
- By the time PDG rises (24-48 hours post-ovulation), the egg has already been released and may no longer be fertilizable 2, 1
What You're Already Doing Right
Your current approach of having intercourse 2-3 days before ovulation is actually optimal:
- This timing places sperm in the reproductive tract before the egg is released, which is ideal for conception 5
- The American Society for Reproductive Medicine recommends timing intercourse in the days leading up to ovulation, not after 5
The Role of Your Progesterone Supplementation
Your 200 mg daily progesterone starting on cycle day 15 is likely intended for luteal phase support, not ovulation timing:
- Progesterone supplementation after ovulation supports the luteal phase and potential implantation 6
- This supplementation would not change the optimal timing for intercourse, which should still occur before ovulation 6
Possible Explanation for the Recommendation
There may be a miscommunication or misunderstanding about what your RE intended:
- Your RE may have meant to use PDG testing to confirm that ovulation occurred (not to time intercourse), as PDG ≥5 μg/mL confirms ovulation retrospectively 6, 3
- The recommendation might have been to continue having intercourse throughout your cycle, with PDG testing used separately to verify ovulation happened 4
- Alternatively, your RE may have been referring to timing based on LH surge (which precedes ovulation by 24-36 hours), not PDG rise 2
What You Should Actually Do
For optimal conception timing, you should:
- Continue having intercourse every 1-2 days starting 3-5 days before expected ovulation 5
- Use LH testing (not PDG) to predict ovulation, as LH surge precedes ovulation by approximately 0.81 days 2
- Use PDG testing only to retrospectively confirm that ovulation occurred, not to time intercourse 6, 3
- Clarify with your RE whether they meant LH surge (predictive) versus PDG rise (confirmatory), as these are fundamentally different markers 2
Critical Pitfall to Avoid
Do not wait until after the PDG rise to have intercourse, as this guarantees you will miss the fertile window entirely since ovulation has already passed 2, 1.