The P+3 progesterone lab test was developed by Dr. Thomas Hilgers after 30+ years of research. He published a study in 2020 which indicated that a progesterone level drawn on P+3 was a good marker to determine that an "ovulatory event" has passed. Please note, the only way to determine if a "healthy ovulation" has occurred is via a Follicular US series.
The P+3 test can be used if a woman is lacking confidence using the CREIGHTON MODEL FertilityCare™ System (CrMS), such as in the case where she may have a "continuous mucus pattern", which can make identifying a true Peak day more challenging.
Table 1 below represents the P+3 progesterone interpretation used by many NaPro providers.
- 0.0–1.0 ng/mL: You have either not yet had an ovulatory event or you are within twenty-four hours of starting your period.
- 1.1–2.3 ng/mL: You are ready to ovulate, or in the midst of an ovulatory event. Repeating another level in 24 hours should clarify your situation. You should consider yourself fertile.
- 2.4–3.0 ng/mL: You have almost for certain had an ovulatory event. Repeating another level in 24 hours to confirm. You should consider yourself fertile.
- 3.1 ng/mL or >: You have had an ovulatory event. Follow the CrMS Basic Method Instructions. You will be naturally infertile starting on the evening of P+4 through your next CD1.
PLEASE NOTE: This test is not for medical, diagnostic or therapeutic purposes. It is for assisting you in identifying a natural ovulatory event and it is intended for use in association with the CREIGHTON MODEL FertilityCare™System.
Reference:
Hilgers TW. The Identification of Postovulation Infertility with the Measurement of Early Luteal Phase (Peak Day +3) Progesterone Production. Linacre Q. 2020 Feb;87(1):78-84. doi: 10.1177/0024363919885551. Epub 2019 Nov 13. PMID: 32431450; PMCID: PMC7016439. Full article here: