By The SABI
The weeks after birth are unlike anything else. Your body has just done something extraordinary, but instead of rest, you’re plunged into sleepless nights, leaking milk, hot sweats, tears that come without warning. As founders and as mothers, we’ve lived this transition. Between us, we’ve breastfed for over four years, and we know how chaotic the postpartum period feels, like your body and your emotions no longer belong to you.
What’s happening beneath the surface is hormonal. Within hours of birth, oestrogen and progesterone collapse to pre-pregnancy levels, while prolactin and oxytocin surge to initiate milk production (NIH Bookshelf). This steep hormonal transition explains why many women feel both physically raw and emotionally fragile in the early days.
Breastfeeding not only helps stabilise these postpartum hormonal swings, but the very hormonal environment it creates is thought to protect mothers long-term, including against breast cancer. In fact, multiple cohort studies and meta-analyses now suggest that breastfeeding reduces breast cancer risk across populations and ethnicities, though the magnitude of protection varies by duration, exclusivity, and cancer subtype.
Prolactin: A Double-Edged Hormone
Prolactin is the hormone of milk production. After birth, levels rise sharply and remain elevated with regular feeding or pumping. Prolactin suppresses ovulation, delaying the return of menstrual cycles, and in turn reduces lifetime exposure to circulating oestrogen, a major driver of breast cancer risk.
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A prospective cohort in Shanghai found that longer durations of breastfeeding were associated with significant reductions in premenopausal breast cancer risk, largely attributed to prolactin-driven suppression of ovarian cycling (American Journal of Epidemiology).
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Meta-analyses confirm that each additional 6–12 months of breastfeeding is associated with lower risk of hormone receptor–positive breast cancers, consistent with this mechanism (BMC Cancer).
Oxytocin: The Hormone of Bonding and Cellular Protection
Every let-down reflex is triggered by oxytocin, which contracts smooth muscle in the breast to release milk. But oxytocin also exerts systemic effects: calming, lowering blood pressure, and improving stress resilience. Emerging evidence suggests oxytocin may have anti-tumour properties, inducing apoptosis (programmed cell death) in breast epithelial cells and modulating immune pathways.
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A review in Endocrine-Related Cancer highlighted the potential anti-proliferative role of oxytocin in breast tissue, suggesting that regular oxytocin surges during breastfeeding could reduce malignant transformation (PubMed).
Oestrogen Suppression and Reduced Hormonal Exposure
High lifetime exposure to oestrogen, early menarche, late menopause, nulliparity, is one of the strongest risk factors for breast cancer. Breastfeeding suppresses ovulation, lowering oestrogen and progesterone levels for months at a time.
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A pooled analysis of African-American women showed that extended breastfeeding was significantly associated with reduced risk of aggressive breast cancers, including triple-negative disease, partly attributed to reduced oestrogen exposure (J Natl Cancer Inst).
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Another large cohort, the Nurses’ Health Study, found that women who breastfed for two years or more across their lifetime had a 23% lower risk of breast cancer compared to those who never breastfed (Am J Epidemiol).
Breast Tissue Differentiation and Involution
Breastfeeding drives mammary epithelial cells into full differentiation, transforming them into milk-secreting cells. Mature, differentiated cells are less likely to become cancerous. Later, when breastfeeding ends, the process of involution clears out old cells, effectively “resetting” the tissue.
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Research in Nature Reviews Cancer describes how pregnancy and lactation cycles may act as a natural remodelling and cleansing process, reducing the pool of vulnerable cells (PubMed).
Metabolic and Immune Pathways
Breastfeeding also impacts insulin, IGF-1, and cortisol, all hormones linked to cancer risk. Lower IGF-1 levels and reduced inflammatory signalling during lactation may help create a less tumour-promoting environment.
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A systematic review in The Lancet Global Health concluded that breastfeeding was associated not only with reduced breast cancer risk, but also with lower maternal risk of type 2 diabetes and ovarian cancer, suggesting broad metabolic benefits
Real Life: The Challenge of Postpartum Balance
The science is clear, but the lived reality is more complicated. Many women stop breastfeeding earlier than they hoped, often because of supply concerns, exhaustion, or lack of support. Globally, more than 60% of mothers end breastfeeding sooner than intended.
Nutrition and rituals play a role in making breastfeeding sustainable. Our Breastfeeding Herbata, with fennel, nettle, moringa, oat straw, tulsi, and vervain, was designed to help mothers feel nourished and calm in this demanding chapter. It is not a cancer-prevention product, but it can support milk supply and ease the hormonal rollercoaster of the postpartum period.
Breastfeeding shapes postpartum hormone balance in ways that extend far beyond the nursery. Elevated prolactin and oxytocin, suppressed oestrogen, and shifts in insulin and immune signalling all contribute to a biological environment less favourable to breast cancer.
The protective effect varies, stronger with longer durations, more consistent for hormone receptor–positive and triple-negative cancers, and especially relevant for women at higher inherited risk. But the message is consistent: the hormones that make breastfeeding possible are the same ones that help protect mothers long-term.
HORMONAL & PROUD
Created as a brand to help women navigate the toughest moments in pregnancy, childbirth, postpartum — and practically every stage of life –– The SABI is changing the narrative around our hormones from one of taboo, embarrassment, and loneliness to awareness and even, pride. As more than a wellness brand, The SABI offers a carefully-crafted line of products to carry you through your hormonal journey, including rituals, supportive tools, and ancient herbal remedies that have been tested time and time again by women and now come backed by medicine. The SABI is a blend of science and nature conceived by women who have experienced the joys and deep struggles of bringing a child into the world, the pains of a heavy, difficult period, miscarriage, and difficulty conceiving.
We invite you to get to know your body and its cycles better –– to really understand what is going on inside. Learn to use your hormones to your advantage no matter your stage of life, and know that you can support and balance your hormone levels. We are here to help with the information, understanding and natural tools to support your body and the emotional process along with it.
DISCLAIMER
The SABI blog and articles are not meant to instruct or advise on medical or health conditions, but to inform. The information and opinions presented here do not substitute professional medical advice or consultations with healthcare professionals for your unique situation.
References
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Neville MC, et al. Endocrine control of lactation. NIH Bookshelf.
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Zheng T, et al. Lactation and breast cancer risk: cohort study in Shanghai. Am J Epidemiol. 2000.
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Islami F, et al. Breastfeeding and breast cancer risk: systematic review and meta-analysis. BMC Cancer. 2013.
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Cassoni P, et al. Oxytocin and its receptors in cancer: a critical review. Endocr Relat Cancer. 2014.
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Palmer JR, et al. Breastfeeding and risk of aggressive breast cancers in African-American women. J Natl Cancer Inst. 2014.
