EFFECT OF NURSING PATTERN ON POSTPARTUM ANOVULATORY INTERVAL.
Contributors: University of California, Davis.
Published: 1989
Number of pages: 162
Subjects: Engineering, Biomedical.; Biology, Animal Physiology.
Description: Seventy-two nursing mothers participated in a nation-wide study by self-reporting the time and length of each nursing bout during the day and night, their waking basal body temperature and other indicators of fertility throughout the course of their postpartum anovulatory interval. Life table analysis of the date of first postpartum ovulation yielded a median of 12.8 months postpartum anovulatory interval for the study population.

Survival analysis of the postpartum anovulatory intervals and the time-series nursing-pattern data showed that the interval between nursing bouts, the frequency of nursing bouts and the daily total nursing time all significantly (p $<$ 0.05) affect the hazard function of the month-specific rate of ovulating. Maternal weight-for-height was found to be not related to the hazard rate for the first postpartum ovulation; however, liquid supplementation of breastfeeding as well as scheduled breastfeeding were found to be significantly related.

The underlying ovulation hazard function for the study population was estimated directly from the life table and indirectly by fitting a time-delayed Weibull distribution to the data. The analyses suggest that intermittent nursing (short, frequent nursing bouts) may extend the postpartum amenorrheic interval 4.0 months beyond that afforded by dosed nursing (longer, infrequent nursing bouts).

A mathematical model of prolactin release, distribution and removal is considered. The results of a series of simulation studies suggest that a limited capacity of the pituitary to store prolactin and the existence of refractoriness in the prolactin transformation phase could contribute to a lowering of the average concentration of circulating prolactin with a dosed nursing pattern, and to a maintenance of breastfeeding-induced hyperprolactinemia with an intermittent pattern of nursing. Such a model would be consistent with the ovulation-delaying effect of intermittent nursing patterns observed in the population studied.
Notes: Source: Dissertation Abstracts International, Volume: 50-08, Section: B, page: 3592.

Thesis (PH.D.)--UNIVERSITY OF CALIFORNIA, DAVIS, 1989.

School code: 0029.