Hi and welcome to Healthcare Magic. Thanks for your question... Thyroid disorders, particularly hypothyroidism (which you may be having) is associated with both depression, weight gain and menstrual irregularities. Weight gain is one of the common symptoms of hypothyroidism. Also, thyroid disorders can sometimes be a causative or precipitating factor for depressive and anxiety disorders. Thyroid disorders are also well known to cause menstrual irregularities. Since you are already experiencing irregular periods, it is likely that this missed period could be due to a menstrual irregularity caused by the thyroid problem. However, the only way to find out if your missed period is due to pregnancy or not is to do a pregnancy test. So, I suggest that you have a pregnancy test done to clear your doubts with certainty. Also, remember that it is important to take proper and regular treatment for your thyroid problem, because if not treated properly, it can worsen your depression or dampen the treatment response. All the best. - Dr. Jonas Sundarakumar Consultant Psychiatrist