---
title: Do immune system cells change during the menstrual cycle? | Niyora
description: Yes, a key immune molecule called IL2 drops during the second half of the cycle. This might explain why some women get more infections before their period.
url: https://niyora.com/research/papers/luteal-phase-of-the-menstrual-cycle-in-young-healthy-women-is-associated-with-2001/
---

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- Do immune system cells change during the menstrual cycle?

Lab study, 2001

# Do immune system cells change during the menstrual cycle?

Yes, a key immune molecule called IL2 drops during the second half of the cycle. This might explain why some women get more infections before their period.

 Early or limited evidence

18 healthy women aged 19-29 with regular menstrual cycles

## What they did

In 18 healthy women aged 19-29, they measured immune and hormone levels at five different times during the cycle: days 5, 8, 14, 18, and 25.

## What they found

IL2 levels and the number of immune cells producing IL2 both decreased during the luteal phase (the second half of the cycle).

## What it means for you

Lower IL2 might make women more vulnerable to infections before their period. It might also help the body prepare for pregnancy by reducing immune response. The main limitations are the small sample (18 women) and that all were young and healthy.

18

women studied

19-29

age range in years

5

time points measured during cycle

## About the study

Original title Luteal phase of the menstrual cycle in young healthy women is associated with decline in interleukin 2 levels Authors Trzonkowski P, Myśliwska J, Tukaszuk K et al. Journal Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme Year 2001 Study design Lab study What was tested None; observation at different cycle phases. Read the paper [doi.org/10.1055/s-2001-15420](https://doi.org/10.1055/s-2001-15420)

## Topics

[Adolescents and young people](https://niyora.com/research/topics/life-area-adolescents/)

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