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If you have been sexually active (without protection/being on regular birth control measures), the chances of pregnancy cannot be ruled out. If you have been having irregular periods, the delay could be due to anovulatory cycles or PCOD, ovarian cysts, hormonal derangements, etc. Consider visiting your doctor/gynecologist for thorough evaluation to look for the underlying cause. If pregnancy is suspected, look out for development of any other new symptoms and consider visiting your doctor/gynecologist for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). If pregnancy gets ruled out, go ahead with further evaluation to look for the cause for absent periods. Get started on treatment as appropriate (as indicated by examination findings and investigation results) to get back your periods and regulate them. Be in regular monitoring and follow-up with your treating doctor/gynecologist and report any new/abnormal symptoms immediately. Take adequate rest. Drink plenty of water. Maintain healthy diet and lifestyle.
Take care.