Implantation happens on average 9 days after ovulation, with a normal range of 6-12 days. Some people have suggested that there are some BBT temperature charts which may show signs of implantation such as a triphasic BBT curve (a rise to a third level of temperatures) or an "implantation dip" (a one-day decrease in temperatures about a week after ovulation).
Neither a triphasic curve nor an "implantation dip" are sufficient enough evidence that pregnancy has happened and it gives too many women false hope.
- Many women with a triphasic pattern and/or a dip in temperature are not pregnant.
- Many women who are pregnant do not have a typical triphasic pattern or a temperature dip, and,
- Some women who are not pregnant may have either a triphasic pattern and/or a dip or both.
The three best indicators of a pregnancy are:
- The absence of your period (amenorrhea) 15 or more days after ovulation.
- A basal body temperature that is elevated 14-15 days or more, and
- A positive pregnancy test.
Prior to missing your period there are no reliable enough signs of pregnancy on your BBT curve. The best (and some say only) way to diagnose a pregnancy from the BBT curve is to have no period (amenorrhea) 15+ days after ovulation. Anything else is just speculation.