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Period may be delayed even in those ladies who have regular periods but it is also important to rule out pregnancy
Urine pregnancy test depend upon hCG
hormone in urine which is excreted only after fertilization of ovum.
Urine pregnancy test may be false negative or weakly positive in early days due to less amount of hCG in urine.
Generally,Urine pregnancy test is done after missed period for confirmation of pregnancy,but Ultrasound
of pelvis is the investigation of choice for confirmation of pregnancy.It can detect G-sac earliest.
Hope i have answered your query.