Hello dear Understand your concern Most common cause of delayed period is pregnancy if you had unsafe intercourse in the unsafe time of your period. Chance of pregnancy is less as you are on the implanon because its failure rate is 0.05 % only. You have to go for pregnancy test if period is delay more than 10 days from your normal date.(Pregnancy should be confirmed by urine pregnancy kit, blood HCG, USG ). If pregnancy test is negative you have to confirm the other causes. Not the other causes of delayed period: excessive stress, change in dietary habit, ovarian dysfunction/cyst, endometriosis, hormonal imbalance, thyroid dysfunction. Following investigations are needed: full hormone profile, endometrial biopsy, ovarian follicle study. Meanwhile avoid stress, start regular excercise like yoga, take healthy diet with fruits like papaya, orange and pine apple Hope this may help you Best regards Dr. Sagar