Sometimes the periods are delayed due to stress, hormonal imbalance, obesity, chronic illness, excessive
exercises etc. The implantation bleeding is when the embryo/fertilized eggs get attached to uterus. The
implantation bleeding is very light and red in color and is more of a spotting and can be for 1-2 days.
Spotting means bit of blood from vagina which does not reach panty and can be swiped. The spotting is also
seen in non pregnant state between periods in the middle of cycle due to ovulation and 1-2 days after periods
and 2-3 days before periods is considered normal. You can always test for pregnancy if you have a doubt.
Delayed periods or missed periods are not always due to pregnancy. Hope it helps. Take care.