HeraSphere #39: Motherhood & Your Brain

Hi friends,

Happy Mother’s Day! Last year, I wrote about the gift of estrogen to mark this holiday. Flowers are lovely, but I can buy those for myself. This year I'm giving you some neuroscience instead.

A few nights ago, I was at Union Stage for a moms-only dance party — women in everything from sequins to sweatpants, moms of newborns next to empty nester moms. I was there with a group of fellow 9th grade moms, and somewhere between songs I found myself thinking about the early years, when I became a mom for the first time and had absolutely no idea what was coming.

Everyone talks about what pregnancy does to your body. That part is more visible. Nobody talks about what it does to your brain. The changes are significant, measurable, and some of them are still running in the background right now, whether your youngest is three months old or out of college.

The TL;DR

• Pregnancy restructures your brain for threat detection, and that rewiring interacts directly with perimenopause, amplifying anxiety and sleep disruption in ways most women never connect back to motherhood.

• Postpartum depression and perimenopause share the same neurological mechanism. If PPD was in your history, treated or not, your brain has already navigated one estrogen crash. The second one deserves your attention.

• The light sleep started with your first baby and never fully reset. Maternal hypervigilance and perimenopausal sleep disruption stack. There are specific reasons and fixes.

• Your pregnancy complications are cardiovascular data your doctors may not have. Preeclampsia and gestational hypertension predict heart disease risk decades later. Most women never connected those dots.

• Your mother figure's health history is your most predictive data set, and if you can still call her or see her, the most important health investment you can make this Mother's Day might be in her, not just yourself.

Your Brain Got Remodeled During Pregnancy

• Pregnancy restructures the brain. This shows up on MRI scans. A landmark study tracked women's brain scans before pregnancy, during, and two years after delivery. Gray matter volume decreases in specific regions: targeted pruning, similar to adolescence. The regions that change are precisely those involved in reading social cues and detecting threat.

• Your amygdala becomes more reactive after pregnancy. This is why you bolt awake at the smallest sound. Why a mother can hear her baby breathe across the room. The brain is calibrating itself for what new motherhood requires.

• These structural changes are detectable at least two years postpartum. Some researchers believe certain adaptations last longer.

• In perimenopause, this rewiring matters more than most women know. Estrogen has been moderating that same threat-detection system for decades. As it drops, the already-primed amygdala has less regulation. The anxiety that feels disproportionate, the hair-trigger stress response, the emotional intensity has a neurological history that likely started in the delivery room.

• If you’re experiencing anxiety during perimenopause: tell your doctor. Ask specifically about estrogen's role in amygdala regulation. Push for specifics, not just "this is normal at your age."

Postpartum Depression (PPD) and Perimenopause

• I didn't experience PPD myself, but I watched close friends go through it — and what struck me was how invisible it was. How hard they worked to seem fine, and how long it took anyone to name what was happening. If any of this sounds familiar from your own past, talk to your OB or a psychiatrist. This is a biology problem with real treatments.

• After delivery, estrogen and progesterone fall faster than at any other point in a woman's life. Within 24–72 hours of birth, both drop off a cliff. Estrogen drives serotonin. Progesterone supports GABA, the brain's primary calming neurotransmitter. When both crash simultaneously, the brain's mood regulation system loses its footing almost overnight.

• Up to 1 in 5 women experience postpartum depression or postpartum anxiety. Most cases go untreated, dismissed as ordinary exhaustion by doctors, partners, and the women themselves.

• Baby blues and PPD are not the same thing. Baby blues (tearfulness and mood swings in the first two weeks) are nearly universal and resolve on their own. PPD is more persistent, more impairing, and has a clear neurobiological driver. The distinction matters for treatment.

• PPD and perimenopause share the same underlying mechanism: estrogen withdrawal. Women with a history of PPD, even mild or untreated, are at higher risk for depression and anxiety during the perimenopausal transition. Your brain has navigated this crash before. That history is clinically relevant.

• What to do today: tell your gynecologist or psychiatrist if you had PPD — even years ago, even if never formally diagnosed. That information should shape how proactively they monitor your mood during perimenopause. If they don't ask, bring it up yourself.

The Sleep Identity Theft of Motherhood

• I was a deep sleeper before kids. I could sleep anywhere and any time. That person has not fully returned, and I always assumed it was just aging.

• Maternal hypervigilance is a documented neurological state. The amygdala rewiring that makes you responsive to your infant also keeps you in lighter sleep stages — your brain stays partially alert, monitoring for distress. For many women, this persists for years after children start sleeping independently.

• Chronic sleep fragmentation has measurable downstream consequences: elevated cortisol, suppressed immune function, accelerated cognitive aging. This compounds over years, not just weeks.

• Maternal hypervigilance and perimenopausal sleep disruption are additive. Progesterone — which promotes deep sleep — declines first in perimenopause. Hot flashes fragment REM. If you were already a lighter sleeper after kids, you're entering the hardest sleep decade of your life starting behind.

• What to do today: if sleep is genuinely broken, ask your doctor about progesterone. For perimenopausal women, it addresses both the hormonal and the sleep problem simultaneously. This is a specific, targeted conversation, and not a general complaint about being tired.

• ICYMI: The science of sleep issue and why its so important for cardiovascular health, brain health, immunity and more.

Your Pregnancy Was a Cardiovascular Stress Test

• Pregnancy complications flag vascular health beyond that pregnancy. Preeclampsia, gestational hypertension, and preterm delivery reveal something about the underlying resilience of your vasculature — and predict future risk.

• Women with preeclampsia have roughly four times the risk of developing hypertension within 15 years of delivery — plus elevated risk of stroke and heart attack. Gestational hypertension and preterm delivery before 37 weeks carry their own elevated cardiac risk downstream.

• Most women were never told. In the chaos of new motherhood, if your OB mentioned long-term vascular risk, it got lost. Nobody followed up.

• Perimenopause adds another layer. Estrogen loss accelerates arterial stiffening and lipid changes. If you had pregnancy complications on top of that, your baseline cardiovascular risk is higher than average — and you may be managing it without knowing.

• What to do today: write down your complete pregnancy history — every complication, every early delivery, every blood pressure flag. Put it on every medical intake form for the rest of your life. If you had preeclampsia, ask for a referral to a preventive cardiologist now. A cardiologist who doesn't ask about your pregnancy history is not doing their job well.

• ICYMI: the full issue on cardiovascular risks from pregnancy symptoms

Your Mother Is Your Crystal Ball

• Your mother's health history is the most personalized longevity data you have. More predictive than most blood tests. Most of us have never systematically collected it. Menopause timing is roughly 50% heritable. The age your mother figure hit menopause is the single most predictive indicator of your own timeline. If she was 48, your planning horizon is probably closer to 48 than 55.

• Bone density trajectory, cardiovascular risk, and autoimmune tendencies all run in families. Knowing your inherited risk profile tells you where to look before symptoms appear.

• I finally asked mom last week when she hit menopause. She was around 55 or 56, which is late by most measures, and if heritability holds, that's probably good news for my timeline. Longer estrogen exposure tends to mean better bone density, lower cardiovascular risk, some cognitive protection. More runway than I expected.

• What to ask your mother and older female relatives: when menopause started, whether she had osteoporosis or fractures, heart disease or hypertension, autoimmune conditions, how her memory is. These are worth knowing.

Taking Care of the Mother Figures in Your Life

• Her bones are the most urgent issue. Women lose up to 20% of bone density in the five to seven years after menopause. If she hasn't had a DEXA scan recently, that's worth raising. A hip fracture is one of the most significant predictors of serious decline in older women, and most are preventable with earlier intervention.

• Isolation is a health crisis. Loneliness increases dementia risk, cardiovascular risk, and all-cause mortality in older adults. If she's widowed, living alone, no longer driving, help find ways for her go get regular contact with others.

• Her sleep problems are probably being undertreated. Older women have the highest rates of insomnia of any demographic, routinely dismissed as normal aging. Poor sleep in older adults accelerates cognitive decline and increases fall risk. If she mentions it, it warrants a real conversation with her doctor.

• Ask about her medications. Polypharmacy is common in older adults and frequently causes cognitive side effects, balance problems, and fatigue attributed to aging. A medication review with her doctor, with someone in the room asking questions, is one of the highest-value things you can do.

• Her estrogen story isn't over. Vaginal estrogen addresses recurrent UTIs, pelvic floor issues, and discomfort that many older women silently endure because no one brought it up. If she's dealing with any of this, it's worth asking her gynecologist about specifically.

What I'm Taking Away

That night at the mom’s dance party, somewhere between Bad Bunny and Cindy Lauper, the carpool schedules and the to-do lists and the thousand things we carry fell away from my brain. We were dancing and laughing, and for a few hours I escaped the reality and responsibilities of everyday life..

That's what I personally need more of. Just a night where to forget, completely, all that I am in charge of.

To every woman who keeps it all together: happy Mother's Day! I hope you get to have a dance party (or whatever is your equivalent) very soon.

xo,

Lilly

P.S. If this made you think of a fellow mom, please send it to her. She may needs it more than she knows.

If you’ve received this email from a friend and want to receive it in your own inbox

Note: While I love diving deep into research and sharing what I've learned about women's health and wellness, I want to be crystal clear: I'm a passionate health advocate and researcher, not a medical professional. Think of me as your well-informed friend who does extensive homework – but not your doctor.

Everything I share in HeraSphere comes from careful research and personal experience, but it's meant to inform and inspire, not to diagnose or treat any medical conditions. Your body is uniquely yours, and what works for one person might not work for another. Always consult your healthcare provider before making significant changes to your diet, exercise routine, or wellness practices, especially if you have underlying health conditions or take medications.

ICYMI, here are a few past issues that you may enjoy: