Originally Posted by
atomic sagebrush
Yeah, I'm sorry but the implantation dip isn't a real thing. What that temp dip actually is is a surge of estrogen called the "secondary estrogen surge" that happens as the corpus luteum starts to wither away. This helps to maintain the lining (and since estrogen causes lower temps the temp drops on some charts) until a baby can finish implanting and send the signal to the body to maintain the corpus luteum longer, and then it will start making progesterone to sustain pregnancy till the placenta forms and takes over that job late in the first trimester.
So unfortunately that dip does not mean pregnancy. Now, just like HLM noted, FF did study this phenomenon and while it's true that there are more pregnancies in charts that have a good dip, that is very very likely because they were more "hormone-y" and not because the dip itself tells us anything - since there are many, many charts that end in pregnancy that don't have that dip, and quite a few charts that DON'T end in pregnancy that DO have that dip. It's one of those correlation does not equal causation type of things unfortunately.
But that is still a very gorgeous chart and I hope that temp rebounds into the stratosphere tomorrow. :)