Interesting Info on "normal" prolactin levels for nursing women

Normal prolactin levels in breastfeeding mothers

Typical baseline serum prolactin levels in women		References
Not pregnant, not lactating	< 25 ng/mL	Walker p. 65, Riordan p. 76, Serri et al. p. 575
Pregnant, at term	200 ng/mL	Walker p. 65
Lactating, 7 days postpartum	100 ng/mL	Riordan p. 76
Lactating, 3 months postpartum	100 ng/mL	Walker p. 65
Lactating, menstruation not started before 180 days	110 ng/mL	Riordan p. 76
Lactating, menstruation started before 180 days	70 ng/mL	Riordan p. 76
Lactating, 6 months postpartum	50 ng/mL	Walker p. 65, Riordan p. 76

Per Riordan (2005, p. 76):

• "Plasma prolactin levels increase the most in the immediate postpartum period but rise and fall in proportion to the frequency, intensity, and duration of nipple stimulation."
• " Prolactin concentration in blood doubles in response to suckling and peaks approximately 45 minutes after the beginning of a breastfeeding session (Noel, Suh, and Frantz, 1974)."
• "During the first week after birth, prolactin levels in breastfeeding women fall about 50 percent. If a mother does not breastfeed, prolactin levels usually reach nonpregnant levels by seven days postpartum (Tyson et al., 1972)."
• Prolactin levels "follow a circadian rhythm: levels during the night (sleep) are higher than during the day."
• Prolactin levels "decline slowly over the course of lactation (Battin et al., 1985; Cox, Owens, & Hartmann, 1996) but remain elevated for as long as the mother breastfeeds, even if she breastfeeds for years (Stallings et al., 1996)."
• Prolactin levels "rise with suckling: the more feedings, the higher the level of serum prolactin. More than eight breastfeedings per 24 hours prevents decline of the concentration of prolactin before the next breastfeeding (Cox, Owens, & Hartmann, 1996; Tay 1996)."

For women who have their prolactin levels checked, Burns & Haddad (1998) note: "When drawing blood for a prolactin level, caution should be used so as not to produce an artificial elevation. Since stress can elevate the prolactin level, the patient should rest (but not sleep) before the sample is obtained. Also, the level should not follow a breast examination and should be drawn in a fasting state."

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