Hi Luisella,

The crinone won't effect a home pregnancy test, but your trigger shot does (contains synthetic hcg), and so do some of the IVF meds (but not all so just check your meds).

With the trigger shot, the number of days it will effect a pregnancy test depends on the dose you had to take. I personally took hpt's from a couple of days after embryo transfer so I could watch the positive line on the tests get lighter and lighter, then kept testing and watched the pregnancy line get darker again as I had conceived.

Here's a picture of my tests. It's hard to tell, but the first two have very faint lines, then it goes away, then the line gets progressively darker again.

To work out how long it should take to be gone based on your dose you can do a little maths. This is how you do it:

1. Work out how many units of hcg was in your trigger shot (10,000 is pretty common...)
2. The hcg has a half life of around 24-36 hours, so every at least 36 hours the hcg level has halved.
3. Starting from the hour you gave yourself the shot, add 36 hours (just to be on the safe side) and halve the hcg level.
4. Check how sensitive the hpt's are that you are using and when you calculations of the synthetic hcg level are lower than the sensitivity level of the hpt, then it should come up negative if you are not pregnant. If it comes up positive then it should mean you are pregnant

For example:
If you say you took the trigger shot at 0 hours and you had 10,000 units of hcg, then you calculations would look like this...
0 hours - 10,000 units hcg
36 hours - 5,000 units hcg
72 hours - 2,500 units hcg
108 hours - 1250 units hcg
144 hours - 625 units hcg
180 hours - 313 units hcg
216 hours - 156 units hcg
254 hours - 78 units hcg
288 hours - 39 units hcg
324 hours - 20 unit hcg
360 hours - 10 units hcg

If your hpt's have a sensitivity of say 100 units, then you should be able to test around the 254 hour mark (day 10-11).

This is based on the highest limit of the half-life, so you could probably test even earlier, but you couldn't be 100% sure of the result.