An investigation of menstruation symptoms across consecutive menstrual cycles and the association with iron deficiency or self-reported heavy menstrual fluid loss : a thesis in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics, Massey University, Auckland, New Zealand

Abstract

Background: Menstrual cycle (MC) symptoms can vary by type and severity among women, and can affect their physical, emotional, and mental health (Schoep et al., 2019). However, few studies have prospectively examined symptoms during menstruation in healthy women. Menstrual bleeding increases iron requirements, and iron deficiency (ID) is common among menstruating women (WHO, 2023). The primary objective of this study was to describe the menstruation-related symptoms experienced by naturally menstruating women. A secondary aim was to examine whether iron status or self-reported menstrual flow contributed to differences in menstruation-related symptoms between women. Methods: Naturally menstruating women (n = 97) aged 18-40 residing in Aotearoa/New Zealand participated in a longitudinal prospective cohort study across up to five MCs. Daily surveys during menstruation captured symptom type and severity using a five-point scale, along with perceived bleeding heaviness. Iron status was assessed via venous blood samples collected at baseline and at the end of the study (mid-luteal phase of the last cycle of data collection). Iron deficiency was defined as serum ferritin (SF) < 30 µg/L and Hb ≥120 g/L. Group differences in symptom severity were analysed using Wilcoxon rank sum tests and multiple linear regression to predict associations with symptom severity. Results: Menstruation-related symptoms were generally mild, with most rated as “none” and “a little.” The most frequently reported symptoms included abdominal cramps, fatigue, mood changes, sleep disturbances, headaches, and reduced concentration. Compared with non heavy bleeders, women with self reported heavy menstrual bleeding (HMB) had higher severity for fatigue, abdominal cramps, and reduced concentration (p < 0.05). Women with ID reported significantly higher severity for fatigue, dizziness, joint pain/muscle cramps, and lower back pain (p < 0.05). In the multilinear regression, iron status did not predict symptom severity; only bleeding heaviness contributed to the overall symptom severity score. Conclusion: Perceived HMB was associated with greater menstruation related symptom severity and independently predicted overall symptom severity. Women who reported HMB experienced higher severity of specific symptoms, including fatigue, abdominal cramps, and reduced concentration. In contrast, ID did not independently predict symptom severity. These results suggest that perceived bleeding heaviness may explain some of the inter-individual variability in menstruation symptom experience.