The implantation dip is called that merely because it occurs around the time of implantation (5-10 days past ovulation).
What happens during this dip in temp is that the cells in the corpus luteum (empty shell of the follicle left behind in the ovary) have been producing progesterone since ovulation. At 5-10 dpo the corpus luteum begins to disintegrate, producing less and less progesterone. Progesterone raises our temperature.
If you are pregnant, the hormone hCG will revive the corpus luteum to continue producing progesterone through the first trimester until the baby takes over production of the hormones. This is when you will see the triphase (third rise) temps.
If you are not pregnant, the temp will drop, then maybe have one more surge (usually don't go any higher than it's already been) and continues to drop until your period arrives.
Love and positive thoughts +++
Momma Kath
