How Long Can Heroin Be Detected In The Umbilical Cord?

How long can heroin be detected in the umbilical cord? I recently found out that I am pregnant and I'm about 17 weeks and I was using heroin up until about a week ago when I found out and went directly and got put on subutex and then I heard about this umbilical cord testing and am worried that it still may show up on this new test even though I've stopped using the heroin...