# monophasic bbt does not mean that you have not ovulated > The plasma concentration of progesterone, the urinary excretion of estrogens, and the basal body temperature were followed in 17 normally menstruating women during 33 menstrual cycles. A monophasic basal body temperature was found in 4 cycles (12 per cent) in spite of the fact that the other parameters investigated suggested that ovulation had occurred. It is thus concluded that the registration of a monophasic basal body temperature during a menstrual cycle does not give sufficient information for the conclusion that the cycle is anovulatory.[[(Johansson, Larsson-Cohn and Gemzell, 1972)#^vllod]] - Some women do not see an increase in BBT despite ovulation occurring - may be due to other factors such as thyroid issues - If yours does not increase, worth getting checked out to see what's going on