Luteal phase abnormalities in early menstrual cycles after pregnancy have been shown to cause confusion in the practice of natural family planning (NFP) for some patients and to restrict severely the number of late infertile days available to others. The cause of the abnormalities is uncertain but appears to be related to the nursing status of the patient.
PIP: Over a 6-year period, 1975-80, all patients who requested instruction in the use of natural family planning (NFP) after pregnancy were offered the opportunity of collating their family planning observations with the results of urinary hormone assays. Participants were asked to record the basal body temperature (BBT) each morning at the same time and at the same body site before arising or imbibing fluid, hot or cold. At night, on retiring, patients were asked to record the mucus signs experienced during the day. The observations recorded were the basic patterns of dryness, of infertile or of fertile mucus, and the transitions between patterns of mucus signs. It was recommended that charts be commenced immediately on returning home after an abortion and within 3 or 4 weeks of term delivery. 24 hour urine collections were assayed for total estrogen and pregnanediol excretion commencing on day 7 for postabortion patients, at 4 weeks for nonlactating postpartum patients, and from 6 weeks for nursing mothers. Participants also were asked to collect urine specimens immediately before ovulation as predicted by the peak mucus sign and again 3-4 days after the temperature rise. The charted mucus signs and BBT observations were examined analogically with the results of the urinary hormone assays and a marginal line, separating the preovulatory from the higher postovulatory BBT, was drawn at the completion of each cycle. Patients were free to remain in the study for as long as they wished, that is, until they were confident that they could practice NFP without further supervision or until planned or unplanned pregnancies occurred. Postovulatory levels of total estrogen excretion greater than the preovulatory peak values occurred in a number of participants. Luteal phases longer than 16 days were found in 6 patients during the study period. A short luteal phase was common in all groups, especially in the 1st post-pregnancy cycle. The important finding was the wide scatter of preovulatory estrogen excretion levels before the 1st postpartum ovualtion, especially in lactating women, yet the mean levels of estrogen excretion were generally greater in non-breastfeeding than in breastfeeding women. Abnormal BBT charts were restricted to cycles with short luteal phases. The position of the marginal line on the BBT charts was stable over the first 3 cycles in 106 of 197 (54%) participants and inconstant in 91 (46%). No significant difference was found in the incidence of constant or variable levels of the marginal line in the successful and unsuccessful participants.