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Nursing frequency, gonadal function, and birth spacing among !Kung hunter-gatherers
Science (New York, N.Y.)
|February 15, 1980
Summary
The !Kung hunter-gatherer mothers
Area of Science:
- Reproductive biology
- Anthropology
- Human lactation
Background:
- The !Kung hunter-gatherers exhibit unique birth spacing patterns.
- Lactation is known to influence postpartum fertility, but mechanisms are debated.
Purpose of the Study:
- To investigate the relationship between nursing behavior and maternal reproductive hormone levels in !Kung mothers.
- To explore the role of interbout interval in lactation-induced infertility and birth spacing.
Main Methods:
- Serum levels of 17 beta-estradiol and progesterone were measured in !Kung mothers.
- Nursing frequency, bout duration, and interbout intervals were recorded.
- Hormonal data were correlated with infant age, nursing patterns, and maternal reproductive status.
Main Results:
- Low maternal serum levels of 17 beta-estradiol and progesterone were observed.
- These hormone levels correlated with infant's age and the interval between nursing bouts, not total nursing time.
- Maternal gonadal function suppression appears to be mediated by prolactin through timed breast stimulation.
Conclusions:
- The interbout interval, not total nursing time, is a critical factor in suppressing maternal reproductive hormones.
- This timing-dependent, prolactin-mediated mechanism likely explains lactation infertility and the birth spacing observed in !Kung populations.
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