Abstract 3435: History of breastfeeding in relation to circulating inflammatory biomarkers
Authors: Lin Nan , Mongiovi Jennifer M. , Farland Leslie V. , Huang Tianyi , Eliassen Heather , Townsend Mary K. , Tworoger Shelley S. , Terry Kathryn L. , Sasamoto Naoko 
Published: March 2024

Abstract
Background: History of breastfeeding has been associated with reduced risk of various chronic diseases in which chronic inflammation is involved in disease etiology, including cardiovascular disease, type II diabetes, breast cancer, and ovarian cancer. However, few studies have investigated the long-term impact of breastfeeding on systemic inflammation. Thus, we aimed to examine the associations between breastfeeding history and circulating inflammatory biomarkers at midlife.
Methods: We conducted a cross-sectional analysis including 3,448 parous women with plasma inflammatory biomarkers in the Nurses’ Health Study and Nurses’ Health Study II. We examined self-reported history of ever breastfeeding (ever vs. never) and lifetime total duration of breastfeeding (never, &lt; 6 months, 7-11 months, 12+ months) prior to the time of blood draw. We calculated the geometric means of eight inflammatory biomarkers [i.e., high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL6], sIL6Rα, IL8, IL10, sIL2-receptor-α(Rα), soluble tumor necrosis factor α receptor 2 (sTNFR2), B-cell activating factor (BAFF), C-X-C motif chemokine ligand 13 (CXCL13)] by self-reported history of breastfeeding status adjusted for age, body mass index (BMI), smoking status, duration of oral contraceptive use, parity, proinflammatory diet, analgesic use, menopausal status, and cohort. Tests for trend were calculated using the median value of each lifetime breastfeeding duration category and modeling as a continuous variable. We also conducted stratified analyses by menopausal status and BMI (&lt; 25kg/m2 vs. ≥ 25kg/m2) at blood draw.
Results: Overall, we did not observe statistically significant differences in circulating inflammatory biomarker levels by history of breastfeeding among parous women. When stratifying by menopausal status at blood draw, total breastfeeding duration was inversely associated with sTNFR2 levels among premenopausal women (P-trend = 0.03) but not among postmenopausal women. Plasma IL8 levels were suggestively inversely associated with breastfeeding duration among postmenopausal women (P-trend = 0.07) but not among premenopausal women. Among women with BMI ≥ 25 kg/m2, plasma BAFF levels were lower in parous women who ever breastfed compared to those who never breastfed [1382.5 (95%CI = 1242.0 - 1539.0) pg/ml vs. 1611.9 (95%CI = 1424.9 - 1823.4) pg/ml; p = 0.03], and suggestively inversely associated with total breastfeeding duration (p-trend = 0.07) but no statistically significant association was observed in women with BMI &lt; 25kg/m2. IL10 was inversely associated with total breastfeeding duration among women with BMI ≥25 kg/m2 (P-trend = 0.007), but not in women with BMI &lt; 25kg/m2.
Conclusion: Overall, history of breastfeeding was not associated with inflammatory biomarkers at mid-life, however the association may vary by menopausal status and BMI.
Citation Format: Nan Lin, Jennifer M. Mongiovi, Leslie V. Farland, Tianyi Huang, Heather Eliassen, Mary K. Townsend, Shelley S. Tworoger, Kathryn L. Terry, Naoko Sasamoto. History of breastfeeding in relation to circulating inflammatory biomarkers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3435.