Periods can be late for various reasons beyond pregnancy. Common causes include:

• Stress, which can disrupt hormone regulation in the brain affecting the menstrual cycle.
• Changes in weight, whether gain or loss, especially if abrupt.
• Increased or intense exercise.
• Hormonal imbalances such as polycystic ovary syndrome (PCOS) or thyroid issues.
• Starting perimenopause, typically between ages 45-55.
• Use of birth control or certain medications like antidepressants or thyroid medication.
• Chronic health conditions such as diabetes or heart disease.
• Breastfeeding can also delay periods due to hormonal effects.

If periods are consistently late or accompanied by other symptoms like weight changes, tiredness, or unusual hair growth, consulting a healthcare provider is recommended. Pregnancy should be ruled out with a test if sexually active and a period is late. Most of these causes affect hormone levels that regulate the menstrual cycle, making the timing of periods irregular or delayed.