###Human: I took pregnancy test as soon as I missed period and it turned negative. Why? ###Assistant: Hi,  Welcome to iclinq.com.  It is unlikely to be a pregnancy as the card is negative. However, if you do not get your regular cycles even after one more week. Do check serum beta HCG (human chorionic gonadotropin) blood test to rule out pregnancy, as some times false negatives can happen with urine tests. Such changes in the cycle pattern that you had mentioned can occur with hormonal imbalance, stress, weight gain, changes in diet and exercise pattern, anemia, hypothyroidism, etc. Hormonal. Serum beta HCG (if the normal cycle does not revert in a week). Hormonal. Reassurance, if the cycle pattern continues to be irregular in subsequent cycles, then you need to take TVS (transvaginal scan). Lifestyle modification.