Cycles longer than 35 days: PCOS, thyroid, and anovulation

Cycles that regularly stretch beyond 35 days (called oligomenorrhea — "few periods") are one of the most common reasons women see a gynaecologist. In most cases the root problem isn't the long wait — it's that the ovary isn't reliably releasing an egg.

Anovulation — the usual explanation

Anovulation means a cycle in which no egg is released. Without ovulation, the second half of the cycle (the luteal phase) doesn't happen properly, so the period is delayed — sometimes by weeks.

Common causes

• PCOS (polycystic ovary syndrome) — by far the most common. Around 10–13% globally and up to 1 in 5 in India. Usually comes with acne, hair growth, or weight around the middle.
• Thyroid problems — both under- and over-active thyroid.
• High prolactin — the hormone that's high during breastfeeding, can rise for other reasons too.
• Very low body fat — common in athletes or restrictive eating.
• Perimenopause in your 40s.

Why it matters

• Anovulation means lower fertility — trying to conceive is harder.
• The uterine lining can build up too much over long cycles, which occasionally leads to abnormal bleeding or, rarely, precancerous changes.
• PCOS raises longer-term risks (diabetes, high cholesterol) that South Asian women face at even higher rates.

What your doctor may test

• Blood tests: testosterone, LH, FSH, thyroid (TSH), prolactin, AMH
• Ultrasound of the ovaries
• Fasting glucose and HbA1c (blood sugar average over 3 months) — especially if PCOS is likely

Lifestyle steps that help

• Movement most days — improves insulin sensitivity, which is often the root problem
• Protein and fibre first at meals to keep blood sugar steady
• 7–8 hours of sleep — sleep loss worsens hormone regulation
• 5–10% weight loss (if overweight) often brings cycles back

When to see a doctor

• 3+ cycles over 35 days in a row
• You're trying to conceive
• You have acne, unwanted hair, or unexplained weight gain