The timing of a positive home pregnancy test depends on the timing of fertilization and implantation. If your periods are regular, and you conceive mid-cycle, you should expect that a hpt will be positive as soon as you miss your period. If the hcg level isn't high enough to give a positive hpt, it can be because 1) you are not pregnant, 2) you conceived later than you thought. There is also the possibility that you conceived, but the pregnancy is not viable. The best thing to do is repeat the hpt in a few days. If you are pregnant, the amount of hcg will double every couple of days. If you still don't get your period, and your periods are usually regular, it's time to visit your provider. They can do a blood test which is much more sensitive, and possibly other bloodwork or ultrasound to determine why your period is late.
at 1:40 PM on Dec. 10, 2008