It can happen at any time; in fact some estimates say that 50-60% of pregnancies end in miscarriage BEFORE the mom even realizes that she is pregnant. I lost mine at 4 weeks, 2 days.As far as your bleeding; painless brown spotting is usually nothing to get too concerned about; but if bleeding/spotting is accompanied by cramps, you have a fever, if the blood is red or pink (rather than brown), if it´s more than just spotting, these are all signs of miscarriage. Unfortunately 20% of KNOWN pregnancies end in miscarriage (ie, the mom has already realized she is pregnant) so it is extremely common. Most often, it is due to a chromosomal anomaly and is no fault of either of the parents; or anything that the parents have or have not been doing. Most couples who have an early miscarriage go on to have healthy pregnancies in the future; so it is usually not an indication of infertility.If you are in doubt, go and see your doc or go to the ED to find out for sure what is going on. They will draw blood to see how much hCG (the ¨pregnancy¨ hormone) you are producing; they may also do a sonogram to see what is going on in your uterus. Best of luck