Inadequate luteal phase usually indicates ovulatory dysfunction: Observations from serial hormone and ultrasound monitoring of 115 cycles

We have studied 100 women with regular menstrual cycles and infertility and tried to assess how frequently an ‘inadequate’ luteal phase (defined by low-peak progesterone levels) follows ‘normal’ ovulation. Normal follicular growth on serial ultrasound scan and follicular disappearance or collapse within 48 hours of the recorded LH peak were taken together as convincing evidence of ovulation. Eighty-three of 115 cycles were judged to be ovulatory and 32 to be anovulatory. A peak mid-luteal phase maximum serum progesterone (Po) level of 32 nmol/L (10 ng/ml) was taken arbitrarily as the cut-off level of discrimination between ‘adequate’ and ‘inadequate’ corpus luteum function. Serum progesterone was undetectable (< 2.5 nmol/L) throughout in 2 cycles while the maximum was above 32 nmol/L in 102 and detectable but less than 32 nmol/L in 11. Of the latter only 1 was ovulatory. We conclude that cycles with low luteal phase Po levels represent luteinization without ovulation.