Q: I am 16 days past my ovulation, and I took a home pregnancy test and it came back negative. Could I still be pregnant?

A: Most urine pregnancy tests are positive within 1-2 days after you miss your period. But even though you tested negative, you still may be pregnant.

Here are some reasons for pregnancy tests becoming positive later, even if you are pregnant:

A home pregnancy test (HPT) becomes positive only when a certain level of the pregnancy hormone hCG is detected in your urine. Because of different sensitivity levels, different brands of pregnancy tests become positive earlier than others. Brands with higher sensitivity levels turn positive later than those with lower sensitivity levels.

Urine hCG levels vary a lot from one pregnancy to the other. About 20% of pregnant women test positive later than 15-16 days post ovulation, so for one in five pregnant women, it may normally take some more days for the home pregnancy test to become positive. You may want to wait another couple of days and then retest again.