Is BBT charting one hundred percent accurate?

China
March 4, 2009 8:52am CST
My ultrasounds seem to be off by about 3 weeks now. I temp'd using the BBT method and here is some background. LMP was Sept 5th. Temps were low until Tuesday when they went up in the usual pattern when I ovulate. Then went higher again a few days later. So basically my temps pre-ovulation were around 97.3. After ovulation 97.7 then went up to 98.3 and stayed there. I took a HPT on October. Two actually that were positive. My question is, isn't my dating more accurate than the ultrasound? Why does my doctor insist on using the ultrasound to date my pregnancy when I have been charting my cycles and basically know when I conceived, or am I mistake and this is not a full proof method?
1 response
@maximax8 (31053)
• United Kingdom
5 Mar 09
The dating of pregnancy can differ depending on who is calculating it. Your LMP was September 5th so I would calculate that your due date will be around June 12th. I know that doctors use the LMP date as the due date. A lady can have a dating scan and in my home country that is when the lady thinks she is 12 weeks pregnant. I had mine and I wasn't 12 weeks pregnant but really 13 weeks pregnant. I think BBT charting is quite accurate but doctors prefer their own methods of calculation. Good luck with your pregnancy.