Based on my hormone profile (LH surge to 45 IU on cycle day 13‑14, low luteal‑phase progesterone), did I ovulate on day 13‑14, when should luteal‑phase progesterone supplementation be initiated, how long does the oocyte remain viable after ovulation, and can fertilization still occur after I started progesterone on day 15?

Ovulation Timing and Progesterone Supplementation in Your Cycle

You ovulated on cycle day 13-14 (most likely CD13 evening through CD14 morning), your progesterone supplementation started on CD15 was appropriately timed, and fertilization can still occur because the oocyte remains viable for approximately 12-24 hours after ovulation and sperm can survive 1-4 days in the reproductive tract. 1, 2

Evidence of Ovulation

Your hormone pattern definitively confirms ovulation occurred:

• LH surge peaked at 45 IU/L on CD13, which is the primary trigger for ovulation 3, 4
• Ovulation typically occurs 0-2 days after LH rise, with 70% of women ovulating the day immediately after LH peak and 21% ovulating 2 days after 2
• Your E1G peaked at 288.2 on CD13 then declined appropriately post-ovulation (197.8 on CD14, 133.7 on CD15), confirming follicular rupture 4
• PDG (progesterone metabolite) rose from 3.1 on CD13 to 4.7 on CD14, indicating corpus luteum formation 3, 2

The cramping on CD15 is consistent with post-ovulatory changes and does not indicate ongoing ovulation 4.

Timing of Progesterone Supplementation

Your progesterone supplementation initiated on CD15 at 1pm was appropriately timed for luteal phase support:

• Progesterone supplementation should begin 1-3 days after confirmed ovulation to support the luteal phase without interfering with the ovulation process itself 5
• Starting on CD15 (2 days post-LH peak, likely 1-2 days post-ovulation) allows the natural ovulatory process to complete while providing early luteal support 2
• Your baseline PDG dropping to 2.1 on CD15 suggests inadequate corpus luteum function, making progesterone supplementation medically indicated 3, 5

A common pitfall is starting progesterone too early (before ovulation), which can prevent follicular rupture—you avoided this appropriately 2.

Fertilization Window and Viability

Fertilization remains possible despite starting progesterone on CD15:

• The oocyte remains viable for 12-24 hours after ovulation (approximately 0.7 days mean survival time) 1
• Sperm can survive 1.4 days on average in the female reproductive tract, with 5% surviving beyond 4.4 days 1
• The fertile window extends from 5 days before ovulation through the day of ovulation, with highest conception probability on the day before and day of ovulation 1, 4
• Intercourse on CD15 before progesterone administration at 1pm falls within the viable fertilization window if ovulation occurred CD13-14 6, 1

Exogenous progesterone does not prevent fertilization of an already-released oocyte or interfere with sperm function in the reproductive tract 5.

Luteal Phase Insufficiency Confirmation

Your hormone pattern strongly suggests luteal insufficiency requiring treatment:

• Mid-luteal progesterone should be ≥5 ng/mL (or equivalent PDG levels) to confirm adequate ovulation 3, 5
• Your PDG dropped to 2.1 on CD15, well below the threshold for adequate luteal function 3
• Normal luteal phase progesterone should peak around 7 days post-ovulation and remain elevated—your early decline indicates corpus luteum dysfunction 5

The American College of Obstetricians and Gynecologists confirms that progesterone <6 nmol/L (approximately <2 ng/mL) indicates inadequate luteal function 3.

Clinical Interpretation Summary

• Ovulation occurred: CD13-14 based on LH surge timing and hormonal pattern 2, 4
• Progesterone timing: Appropriately initiated on CD15 5, 2
• Fertilization potential: Remains viable through CD15 intercourse before progesterone administration 1
• Luteal support: Medically indicated based on inadequate endogenous progesterone production 3, 5

Continue progesterone supplementation as prescribed and consider beta-hCG testing 10-14 days post-ovulation (CD23-27) to assess for pregnancy 5.