The Menstrual Cycle
Breast tissue changes throughout the menstrual cycle in response to oestrogen and progesterone fluctuations. In the first half of the cycle (follicular phase), oestrogen causes breast tissue to develop. After ovulation, progesterone causes fluid retention and tissue swelling — which is why many people experience breast tenderness and fullness in the week before menstruation. These changes are normal and reverse after menstruation begins.
Self-Examination Timing
For menstruating people, the ideal time for breast self-examination is a few days after menstruation ends — when hormonal influence on breast tissue is at its minimum. Examining at the same phase each cycle gives the most consistent baseline for noticing change.
Perimenopause
Perimenopause involves fluctuating and eventually declining oestrogen and progesterone levels. Breast tissue often becomes less dense as the glandular tissue that responds to hormones decreases. Some people notice increased breast tenderness during perimenopause due to the hormonal fluctuations of this transition.
Hormone Replacement Therapy
HRT during and after menopause affects breast tissue — combined HRT (oestrogen and progesterone) can increase breast density and has a small associated increase in breast cancer risk. The decision to use HRT involves weighing benefits against risks with your healthcare provider, taking your individual circumstances into account.
