Anonymous wrote:PP that's becAuse once your hcg gets too high they actually don't work as well. The test line either wicks away all the color from the control line or other wonky things. When I was pregnant they stopped working after maybe 22 or 23 or more dpo. They definitely work well around 10-20dpo. I assume your first sono was at 6 weeks or 7-8 weeks pregnant which explains that