Implantation Window Timing After LH Surge
Yes, you are still within the implantation window at 11-12 days post-LH surge, and this window typically extends through approximately day 12-13 after the LH surge (or roughly 6-7 days post-ovulation).
Understanding Your Timeline
Based on your LH surge timing, here's what has likely occurred:
Ovulation timing: Ovulation occurs approximately 28-36 hours after the beginning of the LH surge, or about 8-20 hours after the LH peak 1. A systematic review found the mean duration between LH surge onset and ovulation is approximately 34 hours (95% CI = 30.79-37.03) 2.
Your specific timeline: With your evening LH surge 12 days ago and peak LH 11 days ago, ovulation most likely occurred around 10-11 days ago 3, 1.
The Implantation Window
The implantation window typically occurs 6-12 days after ovulation, with the most common implantation occurring 8-10 days post-ovulation.
The egg remains viable for fertilization for only 12-24 hours after ovulation 4.
If fertilization occurred, the developing embryo (blastocyst) travels through the fallopian tube for approximately 5-6 days before reaching the uterus.
Implantation typically begins 6-7 days after ovulation and can continue through day 12 post-ovulation (which corresponds to approximately day 8-14 after your LH surge).
When Does the Implantation Period End?
The implantation window closes approximately 12-13 days after the LH surge (or about 10-12 days post-ovulation). 4, 5
At 11-12 days post-LH surge, you are in the late implantation window. Most successful implantations have already occurred by this point, but late implantation (up to day 12 post-ovulation) is still possible, though less common.
Clinical Implications
Pregnancy testing: Most sensitive urine pregnancy tests can detect hCG starting around 11-14 days post-ovulation (13-16 days post-LH surge), though some viable pregnancies may not be detectable until 2-4 days later 6.
Progesterone support: The luteal phase (post-ovulation period) requires adequate progesterone levels to support potential implantation. Sustained progesterone levels above 5 μg/mL throughout the implantation window are necessary for successful pregnancy 5.