Genitourinary Syndrome of Lactation: what every breastfeeding mother should know
Breastfeeding is one of the most powerful things a mother can do for herself and her baby.
The benefits are well established and far-reaching. For babies, breast milk provides unmatched nutrition, immune protection, and a foundation for healthy development. For mothers, breastfeeding is associated with reduced risk of breast and ovarian cancer, improved postpartum recovery, and a unique hormonal bonding experience that is truly beautiful.
As more women make the amazing decision to breastfeed again, we are also learning more about how to better support them through the experience — including the hormonal changes that come with it. Because breastfeeding, while deeply beneficial, does shift the body into a low-estrogen state that can bring its own set of challenges.
This is one of those topics I find myself bringing up more and more with my patients — because it affects so many women, and yet so few have ever heard of it.
If you've ever experienced vaginal dryness, discomfort during sex, recurring UTIs, unusual discharge, or difficulty healing from a postpartum injury while breastfeeding — this post is for you. These symptoms are common, they have a physiological explanation, more research is emerging, and they are treatable. You don't have to just push through them.
Let's walk through what's actually happening in your body, and what you can do about it.
Why Estrogen Drops During Breastfeeding
During breastfeeding, prolactin — the hormone responsible for milk production — remains elevated. One of prolactin's effects is to suppress the hormones responsible for ovulation, which in turn keeps estrogen levels very low.
How low? Potentially menopausal-level low. I know, right? In exclusively breastfeeding women, estradiol levels can fall below 20 pg/mL — sometimes even lower. To put that in context, cycling women generally range from about 15–400 pg/mL depending on where they are in their cycle, with a mid-cycle peak often exceeding 300 pg/mL. Postmenopausal estradiol is generally under 10–30 pg/mL — and breastfeeding women can land right in that postmenopausal range.
This is a significant hormonal shift, and the focus of this article will be on the effects it has on the genitourinary tissues.
What Is Genitourinary Syndrome of Lactation (GSL)?
In 2024, a new term was formally proposed: Genitourinary Syndrome of Lactation, or GSL. The term was introduced by Sara Perelmuter alongside a team of obstetricians, gynecologists, and urologists — a remarkable contribution to the field. The goal was to give clinicians a clear, unified way to describe the genitourinary symptoms that arise from the low-estrogen state of breastfeeding. (See full citation in References.)
GSL is not yet formalized in major clinical guidelines — the American College of Obstetricians and Gynecologists has not yet issued specific guidance on it — but its prevalence data really speaks for itself:
Vaginal atrophy was present in nearly two-thirds of postpartum breastfeeding women (63.9%)
Vaginal dryness occurred in 53.6%
Painful sex (dyspareunia) was reported in 60% at three months postpartum, 39.7% at six months, and still 28.5% at twelve months
These are not small numbers. If you're experiencing these symptoms, you are far from alone — and there is a biological reason for all of it.
Why This Low Estrogen State Can Increase UTI Risk, Just Like in Menopause
Estrogen plays an important protective role in the urinary tract. It supports the epithelial lining of the urethra and bladder, maintains an acidic vaginal environment that discourages unwanted bacterial growth, and promotes healthy blood flow to the genitourinary tissues.
When estrogen drops during lactation, the vaginal microbiome shifts. Lactobacillus — the beneficial bacteria that normally dominate a healthy vaginal environment — declines. Vaginal pH rises, and the result is an environment that is more hospitable to the bacteria that cause UTIs and bacterial vaginosis.
Low estrogen during lactation can also contribute to urinary frequency and urgency through potential overactivity of the bladder muscles. This may be why so many breastfeeding women find themselves running to the bathroom more often, or feeling like they can't quite empty their bladder.
What About BV?
Bacterial vaginosis (BV) is driven fundamentally by a loss of Lactobacillus dominance and a rise in anaerobic bacteria — which is exactly the environment that low estrogen during lactation creates. So while there aren't yet published RCTs specifically looking at BV rates in lactating women, the mechanistic evidence in postmenopausal women strongly suggests increased susceptibility in lactating women as well.
Currently, there is a gap in research in this area, as GSL only got a name in 2024 and the research is still catching up. But if you're experiencing recurrent BV while breastfeeding, the underlying hormonal state may be a contributing factor — and worth discussing with your provider.
Can Vaginal Estrogen Help?
This is a question I hear often — and the answer is individualized and encouraging.
For postmenopausal women, vaginal estrogen has a Grade A recommendation for the prevention of recurrent UTIs — the highest level of evidence-based support. The underlying physiology of GSL is the same as menopause (hypoestrogenism), which is why many researchers and experts believe the evidence should extend to breastfeeding women as well. I believe eventually, it will. It just takes a while for the research and guidelines to catch up to expert opinion sometimes.
A large multicenter study (cited below) found that following a vaginal estrogen prescription, 55.3% of hypoestrogenic women experienced one or fewer UTIs in the following year, and 31.4% had none — compared to an average of 3.9 UTI episodes in the prior year. This is a very clinically meaningful reduction in UTIs — and importantly, fewer UTIs means less antibiotic exposure, which matters for both gut microbiome health and the growing concern around antibiotic resistance.
For lactating women specifically, studies have shown minimal to no transfer of estrogen to breast milk with low-dose vaginal estrogen, and no reduction in milk supply. Vaginal estrogen works locally and is not significantly absorbed systemically, which is why it is considered safe during breastfeeding. As always, please work with your healthcare provider to discuss the right timing and formulation for you.
A Note on Postpartum Tissue Healing
One area that leading experts are beginning to discuss — though formal research is still limited — is the potential role of vaginal estrogen in supporting tissue healing after postpartum injuries such as perineal tears or episiotomies. Big shoutout to Dr. Rachel Rubin for her amazing education and advocacy on social media, podcasts, and more.
The physiological rationale is compelling: estrogen is known to increase blood flow to genitourinary tissues, support collagen synthesis, and promote healthy tissue repair. During the low-estrogen state of breastfeeding, these healing mechanisms are naturally blunted — which may contribute to slower or more uncomfortable recovery from perineal trauma.
While we don't yet have robust clinical trials specifically studying vaginal estrogen for postpartum wound healing in lactating women, the mechanism is physiologically sound — and it really does make sense. Some experts in integrative women's health are beginning to explore this application, and as GSL research continues to grow, this is an area I'll be watching closely.
As always, if you've experienced a postpartum injury and are struggling with healing, please discuss all options — including local hormonal therapy — with your healthcare provider. I would be honored to be that person for you - join my waitlist here if you are interested being my patient when I open my clinic in 2027!
In Summary
Breastfeeding is a beautiful and important experience — and it comes with a hormonal state that deserves more clinical attention than it currently gets. If you're experiencing vaginal dryness, pain with sex, recurrent UTIs, urinary urgency, or difficulty healing from a postpartum injury while nursing, these are not things you have to silently endure. They have a physiological explanation, more research is emerging, and there are options.
Understanding your body's physiology is empowering. I hope this post helps you feel more informed and more confident advocating for yourself at your next postpartum visit.
If you'd like to work together, I'd love to support you in your health journey. You can schedule an Individualized Educational Consultation with me here, or join my waitlist here to be one of the first notified when I open my integrative women's health practice in 2027.
*This is educational content only. Not a substitute for medical care. Views are my own and separate from my institution and employer. Always discuss individual health concerns with your personal healthcare provider.
References
Perelmuter S, et al. Genitourinary syndrome of lactation: a new framework for postpartum genitourinary symptoms. Obstet Gynecol. 2024. https://pubmed.ncbi.nlm.nih.gov/38757214/
Tan-Kim J, Shah NM, Menefee SA. Efficacy of vaginal estrogen for recurrent urinary tract infection prevention in hypoestrogenic women. Am J Obstet Gynecol. 2023;229(2):143.e1-143.e9. https://pubmed.ncbi.nlm.nih.gov/37178856/