Impaired follicular growth and abnormal luteinizing hormone surge in luteal phase defect

Abstract

To determine whether luteal phase defect (LPD) is associated with follicular growth or LH surge. The length of luteal phase was determined by the date of ovulation assessed by serial ultrasound measurements of follicle growth on a daily basis. Luteal phase defect was defined when the length of the luteal phase was < 11 days and/or the midluteal serum P level was < 10 ng/mL (31.8 nmol/L). Preovulatory follicular growth was examined by transvaginal ultrasonography. Blood samples taken at midluteal phase were assayed for P. Urine LH levels were determined in samples collected twice a day during periovulatory cycles using rapid urinary assay kits. Infertility outpatient clinic, Tokyo University Hospital. Eighty-one menstrual cycles from 63 normally cycling infertile women who were not administered any medications. Thirty-six of 81 cycles showed LPD. The mean +/- SD maximal preovulatory follicular diameter was significantly smaller in LPD cycles than in non-LPD cycles (16.5 +/- 2.7 versus 19.0 +/- 2.8 mm). The mean +/- SD peak level of urinary LH surge was significantly lower in LPD cycles compared with non-LPD cycles (50 +/- 25 versus 65 +/- 21 IU/L). Luteal phase defect cycles showed a relatively high incidence of abnormal LH surges, namely, lower peak levels or prolonged duration. Luteal phase defect was associated with impaired follicular growth and/or abnormal LH surge. These factors may be involved in the pathogenesis of LPD.