Dr. Mary Claire Haver’s The New Perimenopause (2026) is a work of nonfiction that serves as a health guide for women navigating the hormonal transition preceding menopause. Haver, a board-certified obstetrician-gynecologist and certified menopause specialist, argues that perimenopause is a critical yet misunderstood phase of life. The book explains the systemic biological changes occurring in the female body, challenges the medical status quo that often dismisses women’s symptoms, and provides evidence-based strategies for managing health and preventing long-term disease. Key themes include Perimenopause Is Systemic, Not Gynecologic; Hormones Drive Midlife Mood and Cognition; and Confronting Medical Gaslighting.

Haver is the best-selling author of The Galveston Diet and The New Menopause and has built a large social-media following by providing evidence-based guidance on women’s midlife health. Her work is informed by her own difficult menopause experience, which revealed significant gaps in her medical training and led her to found The ’Pause Wellness clinic, dedicated to menopause care. The New Perimenopause is positioned as a corrective to the fear and undertreatment that followed the flawed interpretation of a key 2002 Women’s Health Initiative study. By framing perimenopause as a key window for prevention, the book serves as a guide for both patients and clinicians, advocating for earlier risk screening and proactive interventions to improve women’s long-term health outcomes.

This guide refers to the 2026 hardcover edition published by Rodale Books.

Content Warning: The source material and guide feature depictions of illness, mental illness, pregnancy loss, gender discrimination, and sexual content.

Plot Summary

Dr. Mary Claire Haver, a board-certified obstetrician-gynecologist, writes from the dual perspective of clinician and patient. She admits that despite decades of medical training, she received almost no education on perimenopause, the transitional hormonal stage preceding menopause that can begin in a woman’s mid-thirties or forties. When her own menopause arrived, she experienced the same dismissals that her patients had long described. That discovery, combined with learning that her clinical practices had been shaped by flawed conclusions drawn from a Women’s Health Initiative study from 2002 on the subject, drove her to research and write first The New Menopause and now this companion volume focused on perimenopause.

Part 1 of the book opens with Amy, a patient whose experience represents the status quo: unexplained weight gain, irritability, vanishing libido, rising cholesterol, sleep disruption, and repeated dismissals by physicians. Amy’s story illustrates a pattern that Haver traces to several systemic causes. Medical schools devote almost no curriculum time to perimenopause. The American College of Obstetricians and Gynecologists perpetuates outdated guidelines, with an average 17-year gap between new evidence and changes in clinical practice. The National Institutes of Health dedicates less than 10% of its annual budget to women’s health, and menopause receives an estimated less than 1% of that share. No standard lab test exists for diagnosing perimenopause, forcing clinicians to rely on symptom recognition that they were never trained to perform. Haver presents her 2024 community survey of more than 800 perimenopausal women, which found the most common symptoms to be hot flashes and night sweats, weight gain, anxiety and depression, sleep disturbances, and fatigue. She frames perimenopause as a once-in-a-lifetime opportunity for prevention, citing research showing that women spend 25% more of their lives in poor health compared with men.

Haver explains the hormonal mechanics she calls the “zone of chaos” (16). Women are born with 1 to 2 million egg cells, of which only about 400 will ovulate across roughly 33 years of menstrual cycling. As the supply diminishes, the pituitary gland sends increasingly intense hormone signals to stimulate the ovaries. The ovaries respond erratically, producing volatile spikes in estradiol, a potent form of estrogen, while progesterone lags because ovulation becomes sporadic. Citing a 1996 study by Dr. Nanette Santoro, Haver emphasizes that this shift is sudden and tumultuous rather than gradual. Estrogen receptors exist in nearly every organ, meaning that hormonal changes affect far more than the reproductive system.

The book catalogs common misdiagnoses that perimenopausal women receive. Fibromyalgia shares symptoms like fatigue, brain fog, and muscle aches with perimenopause, and Haver cites Dr. Vonda J. Wright’s 2024 research introducing the “musculoskeletal syndrome of menopause” as an overlapping framework (45). Interstitial cystitis overlaps with the genitourinary syndrome of menopause (GSM), a condition caused by estrogen deficiency in vulvar, vaginal, and urinary tissues. Long COVID symptoms mirror perimenopause in women aged 40 to 54. The popular but clinically unvalidated label of “adrenal fatigue” is reframed as dysregulation of the hypothalamic-pituitary-adrenal axis, the body’s central stress-response system, driven by estradiol volatility.

Part 2 examines vulnerabilities across multiple organ systems. Haver reframes estrogen, progesterone, and testosterone as neurologically essential hormones, following neuroscientist Dr. Lisa Mosconi’s terminology. Estrogen regulates key neurotransmitters including dopamine and serotonin. Progesterone enhances activity at receptors for gamma-aminobutyric acid, a neurotransmitter that produces calming and sedative effects. Testosterone supports myelination, the insulation of nerve pathways, and the generation of new neurons. Unlike estrogen and progesterone, testosterone does not fluctuate wildly but declines slowly, about 1% to 2% annually from the mid-twenties onward, making attention to this hormonal level crucial in women.

Haver also presents mental-health changes as biologically driven, paralleling the recognized hormonal basis of postpartum depression. Perimenopause quadruples the risk of a first depressive episode, and 57% of women with prior depression relapse during this transition. No diagnostic category exists in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition for perimenopause-related depression, a gap that Haver considers dangerous. She contends that selective serotonin reuptake inhibitors do not address the hormonal roots of these mood disorders and cites evidence that transdermal estradiol, delivered through the skin to bypass the liver and avoid clotting risks, may be more effective for new-onset depression linked to hormonal disruption. Cognitive symptoms affect approximately 85% of perimenopausal women. Dr. Mosconi’s imaging research reveals that women’s brains develop more estrogen receptors as hormone levels decline, an adaptive response that correlates with increased neurological symptoms. Difficulties similar to attention-deficit/hyperactivity disorder have risen sharply among women aged 30 to 49, but Haver cautions that undiagnosed perimenopause may be the true cause for many.

The metabolic consequences of perimenopause are substantial. Haver and a research team introduced the proposed concept of a “metabolic syndrome of menopause” (95), presented at the Endocrine Society meeting in July 2025. When estrogen declines, visceral fat, the metabolically dangerous fat surrounding internal organs, can increase significantly; LDL cholesterol can jump nearly 18.6%; insulin resistance develops; and blood pressure rises as blood vessels lose estrogen-mediated flexibility. GLP-1 receptor agonists, medications originally developed for diabetes, are discussed as emerging tools that improve insulin sensitivity, reduce inflammation, and may work synergistically with estrogen pathways. Liver health is also flagged, with postmenopausal women showing higher rates of metabolic dysfunction-associated steatotic liver disease.

Osteoporosis receives Haver’s urgent attention. Women may lose up to 20% of their bone mass during perimenopause, yet US guidelines do not recommend bone-density screening until age 65. Haver advocates for baseline DEXA scans, imaging that measures bone density, in the late forties or early fifties. Sarcopenia, the progressive loss of skeletal muscle, is framed as osteoporosis’s counterpart. The Study of Women’s Health Across the Nation found that women lose an average of 1% to 2% of lean body mass per year during the menopausal transition. Resistance training, protein intake of 1.2 to 1.6 grams per kilogram daily, and creatine supplementation are presented as evidence-based countermeasures.

Sleep disruption also affects 40% to 50% of perimenopausal women, driven by the dual loss of estrogen’s circadian rhythm regulation and progesterone’s sedative effects. Obstructive sleep apnea is flagged as severely underdiagnosed in women, with an estimated nine out of 10 cases undetected. Treatment strategies range from hormone therapy and cognitive behavioral therapy for insomnia to targeted supplements like magnesium, L-theanine, and melatonin.

Part 3 covers sexual function, fertility, and menstrual changes. Haver describes declining desire and painful intercourse from GSM, noting the absence of approved testosterone therapy for women in the US despite international guidelines supporting its use. She explains Dr. Emily Nagoski’s distinction between spontaneous desire and responsive desire, the latter emerging after rather than before physical or emotional intimacy and being far more common in women. Fertility after 35 is addressed with reproductive endocrinologist Dr. Natalie Crawford, who found that egg quality deteriorates faster than quantity and that fertility tracking becomes unreliable as hormonal signals destabilize. Menstrual irregularities are explained through the PALM-COEIN diagnostic framework, which classifies causes as structural (polyps, fibroids) or non-structural (ovulatory dysfunction).

Part 4 presents the treatment landscape. Haver details two approaches to perimenopausal hormone therapy: suppressing and replacing hormones with higher-dose contraceptive formulations or supporting fluctuating levels with low-dose bioidentical estradiol and progesterone. She lists absolute contraindications (factors that should negate the use of certain treatments), corrects misconceptions that exclude women from therapy unnecessarily, and criticizes testosterone pellet therapy for routinely producing dangerously elevated levels.

The lifestyle chapter consolidates recommendations around four pillars: anti-inflammatory nutrition emphasizing 30 different plant foods per week and elevated protein intake, resistance training and cardiovascular exercise, sleep optimization, and daily stress management. A final chapter provides scripts for navigating healthcare appointments and a comprehensive list of lab tests for perimenopausal patients.

The book closes with a letter from Haver to her 35-year-old self, distilling its messages into five directives: Shift from pursuing thinness to building strength, prioritize nutrients over calories, educate yourself about menopause, view aging as a privilege, and invest in function and longevity. She frames perimenopause as a window for prevention rather than a decline and positions the book as part of a broader movement to transform the standard of women’s healthcare.