Prolactin levels in nursing mothers

Area of Science:

• Endocrinology
• Reproductive Biology
• Human Physiology

Background:

• Prolactin (PRL) is a key hormone in lactation and reproductive function.
• Postpartum hormonal profiles, particularly prolactin, are influenced by infant feeding patterns.
• Understanding prolactin dynamics is crucial for postpartum health and family planning.

Purpose of the Study:

• To investigate the relationship between infant nursing frequency and maternal plasma prolactin (hPRL) levels over 24-hour periods.
• To determine the duration of elevated hPRL and its association with amenorrhea in nursing mothers.
• To examine the temporal response of hPRL to nursing episodes and nighttime release patterns.

Main Methods:

• Plasma hPRL concentrations were measured in four nursing mothers over 24-hour periods.
• Blood samples were collected using indwelling catheters.
• Infant nursing times and maternal sleep periods were meticulously recorded.

Main Results:

• Elevated hPRL and amenorrhea persisted for up to 13 months postpartum in mothers with frequent nursing.
• One mother with less frequent nursing experienced menstruation with lower prolactin levels while continuing lactation.
• Plasma hPRL showed a decreased response to nursing episodes after two months postpartum.
• Nighttime hPRL release was higher in nursing mothers, similar to normal physiological patterns.

Conclusions:

• Prolactin levels can remain elevated for over a year postpartum in nursing mothers with continued frequent nursing.
• Lactation is possible even with normal hPRL levels.
• A consistent hPRL rise after nursing episodes diminishes significantly after two months postpartum.
• Nursing mothers exhibit higher nighttime prolactin release, consistent with non-nursing women.