Thingamababy‘s recent posts about home pregnancy tests has brought back some memories for me. After I had my first miscarriage back in 2003, I became obsessed with getting pregnant and staying pregnant – and of course, the first important piece of hardware was a home pregnancy test (HPT). I learned that HPTs work by detecting the pregnancy hormone, human chorionic gonadotrophin (hcg), in urine. The first morning urine contains the highest concentration of hcg so I learned to take the test as soon as I woke up. Although HPTs are qualitative rather than quantitative tests (i.e., the tests can only detect the presence of hcg but not measure how much of it there is), some HPTs are more sensitive than others.
Back in 2003, First Response was one of a handful of tests (and the most widely available) that tested hcg levels as low as 25 mIU (milli-international units per milliliter). Most widely available tests at that time detected minimum levels of 40 mIU. You can imagine how many First Response tests I went through until I finally got pregnant with Alex (and even then, if I recall correctly, I repeated the test one or two days after I got my positive HPT just to “make sure”).
It seems that HPTs have gotten better in the last four years, however. This chart, which I checked obsessively back in the day, lists the hcg levels that HPTs are able to detect, and the number of tests claiming to detect low levels of hcg has exploded. I would have been all over the tests that claim to detect levels as low as 10 mIU.
An HPT can only detect hcg after implantation occurs. Implantation usually occurs by 10 days post-ovulation (dpo) but implantation often occurs after 10 days and a negative HPT at 10 dpo does not mean a woman isn’t pregnant. A woman who’s not pregnant would get her period at 15 dpo, so 15 dpo is the “first day of a missed period.” (No, you’re not crazy if you test every day starting at 10 dpo. I wouldn’t test earlier than that because you’d really be setting yourself up for disappointment. But if you couldn’t wait, I’d certainly understand how you feel.)
For some bizarre reason, anecdotal evidence indicates that some women don’t respond to certain tests. For example, I knew one woman who never got a positive result on with a First Response test even when her Clearblue Easy test came out positive. (And I think that was back in the day when Clearblue Easy didn’t detect 25 mIU so at that point, any test should have been positive.)
Finally, I leave you with a cautionary tale. If you stare too long and hard at the stick, you will eventually see a VERY faint line and ask yourself, “Is it? Could it be?” And especially if it hasn’t been more than 15 minutes since you took the test, minimizing the possibility that it’s an evaporation line, you may very well convince yourself that you are pregnant. I hate to break it to you, but I’m telling you because I wish someone had told me: You’re probably staring so hard that you’re seeing the line that would have appeared if the test were positive. And that, I think, is the benefit to digital HPTs – there’s no “Is that a line?” false hope. Digital tests may be more expensive, but I wish they’d been around in 2003. The HPT companies would have made a lot more money off of me.