PMOS (formerly PCOS) and irregular periods: why, and what to do?
PMOS disrupts ovulation: it happens late, or not at all some months. That is why the large majority of women with the condition have irregular, often long, cycles. You cannot "fix" that rhythm yourself, but you can observe it honestly, and that is what makes medical follow-up effective.
Why PMOS disrupts the cycle
PMOS, polyendocrine metabolic ovarian syndrome, was called PCOS until 2026 and many women still know it by that name. It rests on a hormonal imbalance: too many so-called male hormones, often insulin resistance, and ovaries that prepare many follicles without bringing one to ovulation.
The result: ovulation happens late, unpredictably, or not at all some months. Since your period comes about two weeks after ovulation, it comes late, or not at all. Irregular cycles are one of the signs used for diagnosis, and the large majority of women with the condition have them. Cycles of 40, 60, 90 days are not rare.
What you can track yourself
You cannot decide your ovulation. But you can do one thing your doctor cannot do for you: observe your cycle over time.
- The first day of each period, even when it comes after two months. This is the data that matters most.
- Bleeding outside of periods, because with PMOS you can bleed without having ovulated, and that can be mistaken for a period.
- The symptoms that come with it: acne, fatigue, sugar cravings, mood. Over several months, they draw a picture.
A classic app, set to 28 days, does not help you: it announces periods that do not come and shows "late" for weeks. An app built for long cycles gives you a window instead of a date, and does not make you feel guilty when the window is wide.
What belongs to your doctor
PMOS can be managed, and well. Depending on your situation and your plans, your doctor may suggest:
- a hormone panel and an ultrasound to confirm the diagnosis;
- changes in diet and physical activity, which act on insulin resistance and, for many women, on cycle regularity;
- a treatment to regularise cycles, or to trigger ovulation if you are trying to conceive;
- monitoring of weight, blood sugar and blood pressure, because PMOS raises certain long-term risks.
When to see someone
- Your cycles regularly go past 35 days, or you go more than three months without a period.
- You have irregular cycles with acne, increasing hair growth on the face or body, or weight gain that is hard to explain.
- You are trying to conceive: with PMOS, early support changes a lot.
- You have a PMOS diagnosis and no follow-up for more than a year.
Lovae is a wellbeing app, not a medical device. It is built for cycles that follow no rule, but it replaces neither the diagnosis nor the treatment.
Sources
- Comprendre le syndrome des ovaires polykystiques : définition, causes et fréquence (Assurance Maladie, ameli.fr)
- Symptômes, diagnostic et évolution du syndrome des ovaires polykystiques (Assurance Maladie, ameli.fr)
- Polyendocrine metabolic ovarian syndrome, PMOS, formerly PCOS (NHS)
- Teede HJ et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome (PubMed)
Pages consulted on 4 September 2026.