Missed Period for 6 Weeks: Causes, Symptoms, and What to Do

A missed period for 6 weeks (42 days) warrants evaluation. Pregnancy is the most common cause in reproductive-age women, but many other factors can delay menstruation.

Step 1: Rule Out Pregnancy

• Home pregnancy test (HPT) — use first-morning urine. Sensitivity ~25 mIU/mL; accurate at this point.
• If negative, repeat in 48h or get quantitative serum β-hCG (definitive).
• If positive → prenatal care.

Non-Pregnancy Causes of Secondary Amenorrhea (≥3 months / 2 cycles)

1. Hormonal:
   • PCOS (most common) — oligo/anovulation, hyperandrogenism.
   • Thyroid: Hypothyroidism (↑TRH → ↑prolactin) or hyperthyroidism.
   • Hyperprolactinemia: Prolactinoma, medications (antipsychotics, metoclopramide, opioids).
   • Premature ovarian insufficiency (POI): <40yo, ↑FSH, ↓AMH.
   • Perimenopause: Irregular cycles, vasomotor symptoms (typically 40s–50s).
2. Hypothalamic (functional hypothalamic amenorrhea): Stress, low weight/energy availability (athletes, eating disorders), excessive exercise → ↓GnRH pulsatility.
3. Medications: OCPs (withdrawal bleed may be absent), depot medroxyprogesterone, implant, hormonal IUD, antipsychotics, antidepressants, chemotherapy, TKIs.
4. Weight change: Rapid loss/gain; BMI <18.5 or >30.
5. Chronic disease: Uncontrolled diabetes, celiac, IBD, renal/liver failure.
6. Pituitary/structural: Sheehan syndrome, craniopharyngioma, empty sella.

Initial Workup

• β-hCG (quantitative)
• TSH, prolactin, FSH, LH, estradiol
• CBC, CMP, HbA1c
• Pelvic ultrasound (ovarian morphology, endometrial thickness)

When to See a Doctor

• 6 weeks amenorrhea + negative HPT
• Any concerning symptoms (hirsutism, galactorrhea, hot flashes, headache, vision changes, pelvic pain)
• Desire for fertility

Treatment targets the underlying etiology: lifestyle modification (FHA), metformin/OCP (PCOS), levothyroxine (hypothyroid), dopamine agonist (prolactinoma), HRT (POI/menopause), etc.