Medical explanation for implantation dip

Dear all,


There's so much talk about the implantation dip on the web, but so little explanation for it that I'm wondering whether its a reliable indicator or not.


I read some doc's comments on the web saying that the dip is just a myth, fabricated by conception-obsessed women. Can anyone offer a medical/physiological explanation for BBT to fall when the fertilised egg plants itself on the uterine lining? I haven't been able to find the answer anywhere!


I'm now 8DPO and yesterday my temp fell but still remained above the coverline. Its now back up today. I also got tons of pastey mucus yesterday, but no spotting which leads me to think that I had a surge in oestrogen and not an implantation dip.

"Reliable indicator" - do you mean of pregnancy? The best indicator is levels of hCG.


From my lay knowledge, a downward shift of the BBT post-implantation could be caused by the timing of implantation during the reproductive cycle, for example very close to menses when there is a natural fall in progestrone levels and the corpus luteum regresses.


There are a few studies which suggest another reason why the BBT might drop but I don't think it's really appropriate for me to go into that here.