---
title: Does suppressing prolactin affect how the menstrual cycle works?
description: No clear difference was found. When prolactin was suppressed to low levels, the menstrual cycle continued with the same pattern of hormonal changes.
url: https://niyora.com/research/papers/lack-of-action-of-prolactin-suppression-on-the-regulation-of-the-human-menstrual-1975/
---

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- Does suppressing prolactin affect how the menstrual cycle works?

Study, 1975

# Does suppressing prolactin affect how the menstrual cycle works?

No clear difference was found. When prolactin was suppressed to low levels, the menstrual cycle continued with the same pattern of hormonal changes.

 Moderate study design

15 women: 8 who were breastfeeding and 7 who had regular menstrual cycles

## What they did

Fifteen women in two groups (8 breastfeeding and 7 with regular periods) took bromocriptine 1 mg three times daily. The breastfeeding group took it for 14 days. The menstruating group took it for a whole cycle, with a cycle measured before treatment. Blood was taken during sleep.

## What they found

Prolactin dropped from 10.8 to 3.7 ng/mL in breastfeeding women and from 9.5 to 3.2 ng/mL in menstruating women. This drop was enough to stop milk production within 24 to 48 hours in breastfeeding women. However, the pattern of hormones during the menstrual cycle stayed the same despite the large prolactin drop.

## What it means for you

Prolactin does not appear to control how the menstrual cycle works. The main limit is the small sample size and lack of a placebo comparison in the menstruating women.

10.8 to 3.7

prolactin drop in breastfeeding women (ng/mL)

9.5 to 3.2

prolactin drop in menstruating women (ng/mL)

24 to 48 hours

time for milk production to stop

## About the study

Original title Lack of action of prolactin suppression on the regulation of the human menstrual cycle Authors del Pozo E, Goldstein M, Friesen H et al. Journal American journal of obstetrics and gynecology Year 1975 Study design Study Participants 48 What was tested Bromocriptine (a drug that suppresses prolactin) - 1 mg three times daily Read the paper [doi.org/10.1016/0002-9378(75)90494-9](https://doi.org/10.1016/0002-9378(75)90494-9)

## Topics

[Low mood and depression](https://niyora.com/research/topics/symptom-depression-mood/)[Diuretics and other drugs](https://niyora.com/research/topics/treatment-diuretics-other-drugs/)[Pregnancy and postpartum](https://niyora.com/research/topics/comorbidity-postpartum/)

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