What can cause people to have irregular periods?

Answer 1

PCOS (poly-cystic ovarian syndrome) Endometriosis Smoking Travelling Being overweight Being underweight A hormone imbalance or disorder An eating disorder, either current or previous A previous pregnancy Medication Illness Use of recreational drugs Dieting Stress Anxiety Not getting enough sleep or getting too much Lack of exercise or over-exercising Not eating enough or eating too much