The Postpartum and Perimenopause Overlap in Women of Advanced Maternal Age

MARKABLE Research Team · August 2026 · 8 min read

Maternal age at first and subsequent birth has risen steadily across high income countries. One consequence is a growing population in whom two major reproductive endocrine transitions are adjacent rather than separated by two decades. The presentations overlap almost completely, and the default attribution is almost always to the postpartum state.

Summary. Delivery produces an abrupt withdrawal of placental progesterone. Lactation then suppresses ovulation and therefore luteal progesterone. In a woman who delivers in her mid forties, resumption of cycling after weaning is commonly resumption into a perimenopausal pattern rather than to a pre pregnancy baseline. The result can be a continuous low progesterone state spanning several years. This article is educational content for clinicians and informed readers, not clinical guidance.

Phase one: the delivery withdrawal

Placental progesterone production ceases with delivery of the placenta, and circulating levels fall over the following one to two days. Progesterone is metabolised to allopregnanolone, a positive allosteric modulator of GABA-A receptors, so this withdrawal removes a substantial component of endogenous GABAergic tone (Belelli et al., 2021).

The clinical significance of this mechanism is no longer inferential. A phase 3 randomised controlled trial of oral zuranolone, a neuroactive steroid acting on synaptic and extrasynaptic GABA-A receptors, in severe postpartum depression reported significant improvement in Hamilton Depression Rating Scale scores compared with placebo at day 15, sustained at days 28 and 45 (Deligiannidis et al., 2023).

Phase two: the lactational extension

During lactation, elevated prolactin suppresses gonadotrophin releasing hormone pulsatility and therefore ovulation. Because progesterone is a corpus luteum product, absence of ovulation means absence of luteal progesterone regardless of whether bleeding has resumed. Prolonged breastfeeding, which is increasingly common, can extend this state for one to two years.

Phase three: resumption is not restoration

This is the step most often missed. The endocrine environment a 45 year old returns to after weaning is not the one she left. Prior and Hitchcock characterise perimenopause as three concurrent changes: erratically higher estradiol, decreased progesterone in anovulatory or short luteal phase cycles, and disturbed ovarian to pituitary to hypothalamic feedback (Prior & Hitchcock, 2011). Prior further notes that ovulatory disturbances occur within cycles of clinically normal length, so returning regular bleeding is not evidence of restored luteal function (Prior, 2018).

The practical consequence is a woman attempting to re establish ovulation precisely as ovulation becomes least reliable, moving from one low progesterone state directly into another.

Why the attribution defaults away from the transition

A sufficient explanation is already present. Fatigue, hyperarousal and fragmented sleep in the parent of a toddler are readily and reasonably attributed to caregiving.
Age is obscured by context. The presence of an infant shifts the clinical frame towards a younger patient.
Testing is least informative here. The post lactational endocrine picture is unstable, and single time point measurement carries little information.
Referral pathways diverge. Postpartum mood symptoms route to perinatal mental health services; perimenopausal symptoms route to gynaecology. The overlap population fits neither pathway cleanly.

Assessment considerations

Establish the timeline explicitly. Date of delivery, date of weaning, date of first return of bleeding, and symptom trajectory across each.
Characterise returned cycles. Length, volume and predictability, rather than presence or absence alone.
Ask about cyclicity of mood. Luteal clustering is the most useful discriminator available without testing.
Screen the depletion mimics. Ferritin with full blood count, vitamin B12, vitamin D, and thyroid function with antibodies. Iron deficiency impairs thyroid hormone synthesis by reducing heme dependent thyroid peroxidase activity (Zimmermann & Köhrle, 2002), so iron and thyroid are not competing explanations. See our review of micronutrient depletion in perimenopause.
Address contraception. Returning cycles, however irregular, indicate returning fertility, and this population may not have raised the question.

For the underlying neurosteroid mechanism, see our review of progesterone and allopregnanolone in perimenopause.

A baseline that spans both transitions

MARKABLE produces a personal baseline across facial, cognitive, sensory and symptom signals that can be repeated over time, making trajectory visible where a single visit cannot.

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Frequently Asked Questions

Can a woman be perimenopausal shortly after giving birth?

Yes. Perimenopause is defined by age and ovarian ageing, not by time since delivery. A woman who delivers at 44 or 45 may already be within the transition, with postpartum and lactational recovery running concurrently. The two states are frequently conflated because the presentations overlap almost completely.

Why does lactation extend the low progesterone state?

Elevated prolactin during lactation suppresses gonadotrophin releasing hormone pulsatility, which suppresses ovulation. Because progesterone is produced by the corpus luteum only after ovulation, the absence of ovulation means the absence of luteal progesterone. Prolonged breastfeeding therefore extends the period without luteal progesterone well beyond the immediate postpartum window.

Why is resumption of cycling different in a woman over 43?

Because the ovary she is returning to is not the one she had before pregnancy. Prior and Hitchcock describe perimenopause as erratically higher estradiol with decreased progesterone in anovulatory or short luteal phase cycles. Resumption after weaning at this age is therefore commonly resumption into an already perimenopausal pattern rather than a return to a prior baseline.

How can postpartum depression and perimenopausal mood symptoms be distinguished?

They are difficult to separate because both involve withdrawal of progesterone and its neurosteroid metabolite allopregnanolone. Cyclicity is the most useful available discriminator: symptoms that track the luteal phase point more towards a cyclical hormonal pattern. Both can coexist, and the distinction is a clinical judgement rather than a test result.

What should be excluded in this population?

Pregnancy and lactation deplete iron, vitamin B12 and vitamin D, and perimenopausal menorrhagia adds further iron loss. Ferritin with full blood count, vitamin B12, vitamin D, and thyroid function with antibodies are reasonable baseline investigations. Iron deficiency also impairs thyroid hormone synthesis through heme dependent thyroid peroxidase, so the two should be assessed together.

Does MARKABLE diagnose postpartum depression?

No. MARKABLE is a general wellness product, not a medical device. It does not diagnose, treat, or cure any condition, including postpartum depression. It produces a personal baseline across facial, cognitive, sensory and symptom signals that can be tracked over time and shared with a clinician.

References

Prior JC, Hitchcock CL. The endocrinology of perimenopause: need for a paradigm shift. Frontiers in Bioscience (Scholar Edition). 2011;3(2):474-486. doi:10.2741/s166
Deligiannidis KM, Meltzer-Brody S, Maximos B, et al. Zuranolone for the treatment of postpartum depression. American Journal of Psychiatry. 2023;180(9):668-675. doi:10.1176/appi.ajp.20220785
Belelli D, Phillips GD, Atack JR, Lambert JJ. Relating neurosteroid modulation of inhibitory neurotransmission to behaviour. Journal of Neuroendocrinology. 2021;34(2):e13045. doi:10.1111/jne.13045
Zimmermann MB, Köhrle J. The impact of iron and selenium deficiencies on iodine and thyroid metabolism: biochemistry and relevance to public health. Thyroid. 2002;12(10):867-878. doi:10.1089/105072502761016494
Prior JC. Progesterone for the prevention and treatment of osteoporosis in women. Climacteric. 2018;21(4):366-374. doi:10.1080/13697137.2018.1467400

Sources were located and verified against PubMed. DOI links are provided so the primary literature can be read directly.

This article is educational content and does not constitute medical advice, diagnosis, or a treatment recommendation, including for postpartum depression. MARKABLE is a general wellness product, not a medical device, and is not intended to diagnose, treat, cure, or prevent any disease.