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Few women can have continued spotting once in a while after implantation bleeding during the first few weeks of pregnancy which can be attributed to hormonal changes. If pregnancy is suspected, then it should be confirmed by examination done by gynecologist/obstetrician along with a blood beta HCG level test.
Report your symptoms to your treating doctor. Look out for other symptoms suggesting early pregnancy like: fatigue, nausea, constipation, increased sleep, hunger and tiredness, mood changes, headaches, back pain, lower abdominal cramps, increased frequency of urine, breast soreness, nipple sensitivity.
Take care.