09/11/2026
I tracked my cycle all the ways so you don't have to!
This is my cycle 3 of the Kegg Clinical Trial.
Fertile window summary:
Actual Fertile Window: Day 13-20
Kegg Fertile Window: Day 13-20
Billings Fertile Window: Day 13-20
Sympto-thermal Fertile Window: Day 8-21
It took 3 cycles for Kegg's algorithm to finially get an accurate fertile window (peak fertility-dark green and overall fertility-light green). If you are counting on their 6 month pregnancy guarantee, this only gives you ~4 months where it actually gives you the best days to try.
This cycle my ovulatory hormone tests actually aligned perfectly with my observed biomarkers. It was likely the previous cycles were off due to the normal adjustment period of postpartum hormones.
⭐️ Estrogen started rising day 13 with the onset of fertile mucus.
⭐️ LH began to rise cycle day 17 (it may have began sooner but morning LH tends to be lower).
⭐️ Estrogen peaked day 16, the first day of slippery mucus.
⭐️ Estrogen fell after peak.
⭐️ Progesterone started rising day 18, with the sudden drying sensation, followed by a temperature rise day 19.
⭐️ Estrogen hit a second peak in the luteal phase.
⭐️ Estrogen and Progesterone fell right before the end of the cycle causing a temperature drop and the beginning of the next cycle.
Because I have continuous discharge, under the sympto-thermal method I am considered fertile as soon as my period ends. With Billings, I am able to identify my personal Basic Infertile Pattern which gives me a much shorter fertile window. Both methods have the same mucus peak day. I confirmed a temperature shift two days after mucus peak, closing my fertile window with the sympto-thermal method.
Overall Billings was the most accurate this cycle. Sympto-thermal was far more conservative, but that is also why it is so effective.