What could be causing my period to be over a month late?
Missing a menstrual period for over a month—often referred to as secondary amenorrhea when occurring in someone who previously had regular cycles—can stem from a wide range of physiological, hormonal, lifestyle, and medical causes. The most common and clinically significant possibility is pregnancy, especially in individuals of childbearing age with intact reproductive anatomy; therefore, a urine or serum beta-hCG test should be the first diagnostic step.
Other frequent contributors include stress-related hypothalamic suppression (functional hypothalamic amenorrhea), significant weight loss or low body fat percentage, excessive physical exercise, and eating disorders—all of which disrupt the hypothalamic-pituitary-ovarian axis and reduce gonadotropin-releasing hormone (GnRH) pulsatility. Polycystic ovary syndrome (PCOS) is another leading cause, often presenting with oligomenorrhea or amenorrhea alongside features such as hirsutism, acne, insulin resistance, and elevated androgens.
Thyroid dysfunction—both clinical and subclinical hypothyroidism—can impair gonadotropin secretion and ovarian responsiveness. Hyperprolactinemia, whether idiopathic or due to a prolactin-secreting pituitary adenoma (prolactinoma), may suppress ovulation by inhibiting dopamine-mediated inhibition of prolactin and interfering with GnRH release. Premature ovarian insufficiency (POI), defined as ovarian failure before age 40, should also be considered, particularly if accompanied by elevated follicle-stimulating hormone (FSH) levels and symptoms like hot flashes or vaginal dryness.
Less common but important etiologies include structural abnormalities (e.g., intrauterine adhesions following dilation and curettage), chronic systemic illness (e.g., celiac disease, inflammatory bowel disease), certain medications (e.g., antipsychotics, chemotherapeutics, long-term opioid use), and genetic conditions such as Turner syndrome or Fragile X premutation.
A thorough evaluation typically includes a detailed history (menarche, cycle patterns, recent stressors, weight changes, medication use, sexual activity), physical examination (including BMI, signs of hyperandrogenism or thyroid disease), and targeted laboratory testing—such as serum beta-hCG, TSH, prolactin, FSH, LH, estradiol, and possibly testosterone or AMH. Pelvic ultrasound may be indicated to assess ovarian morphology and endometrial thickness. Management depends entirely on the underlying diagnosis and may involve lifestyle modification, hormonal therapy (e.g., combined oral contraceptives or cyclic progesterone), treatment of comorbidities, or referral to an endocrinologist or reproductive endocrinologist for further evaluation.