With an unusually light period
and history of
unprotected sex, yes, possibility of
pregnancy is always there. However, the urine test can be false positive or false negative
. Hence do blood HCG estimation test. This is more confirmatory. If this is positive, you are pregnant. If this is negative
, then the cause of
light periods could be stress, PCOD, hypothyroidism or hormonal imbalance. Do discuss this with your doctor and get yourself examined. Take care!