The world of pregnancy tests has advanced beyond all recognition in the twenty odd years since I had my first positive test. Way back then in 1991, home pregnancy tests were a novelty, expensive and a faff, rather than using those mini chemistry sets, most women (myself included) would go to doctor to get a suspected pregnancy confirmed. In those good, old days, you would wait until you had missed a period, then pee in a pot and the doctor would send it off to a laboratory, where some magic would be performed, with the results being available a week later. Today it would be very unlikely that a doctor would even confirm a pregnancy as home pregnancy tests are now as simple as peeing on a stick, with the results being almost instantly available, sometimes up to 6 days before your period is due. While these early pregnancy tests are wonderful in one way, they could well be a two-edged sword.

Many years ago (in the 1940s) pregnancy tests involved injecting urine into frogs, which then needed to be dissected to see if the urine had triggered ovulation. Amazingly it is the same hormone that triggers modern pregnancy tests that triggered this ovulation, that is hCG, or to give it it's long name human chorionic gonadotropin. This hormone is generally only excreted during pregnancy and is actually excreted by the fertilised egg as it embeds in the womb (implantation). As the pregnancy develops the levels of hCG will steadily rise, doubling on average every 48-72 hours. When home pregnancy tests first became popular they could only pick up relatively high concentrations of hCG and so could only be used after you had missed a period. Today there are an increasing number of home pregnancy tests that react to much smaller concentrations of the hormone, some pick up 25mui, some 20mui and some will give a positive result at just 10mui.

You would, perhaps, expect that all of these highly sensitive tests are extraordinarily expensive, but in truth there is just a wide price range as there is with standard tests and it doesn't always follow that the more expensive the test the better. Over the last three years I've used a fair few different early pregnancy tests, from the so-called earlier, First Response, through to the Super drug own brand and on to the super cheap no-names, and to be perfectly honest I've not found the price has anything to with how many days before your period is due you get a positive result. The only real difference I have found is how easy it is to read the results, with Superdrug coming in first, followed by the no-names, with the First Response trailing behind.

There are advantages to these early pregnancy tests, but there are just as many disadvantages, I'll start with the advantages. With these more sensitive tests it is possible to find out you are pregnant well before your period is due and make the necessary life-style changes to give the baby the best start possible. Another advantage of these early tests is that if you have an existing medical condition or pregnancy needs early monitoring or support for any reason then you can get this help as soon as possible. The final real advantage is that there is no real wait factor, in this modern world we seem to want everything to happen yesterday and with these tests it is possible to find out when you really are barely pregnant.

As far as disadvantages go there are four main ones that I can think of. The first of these is that while these early tests can detect a pregnancy as early as six days before your period is due, in reality the earlier the test is taken the less accurate the result. This is partly down to the fact that while doctors work on the "average" 28 day cycle,assuming ovulation occurs 14 days after the last period started with an 14 days until the next period, in reality not every body sticks to this cycle. Even those with a 28 day cycle may not ovulate until day 16 or 17, meaning it takes a little longer for the fertilised egg to implant and begin to produce hCG. Then you have to consider that hCG levels will not raise at the same rate as the next person, all this means that you may take an early test 6,5,4,3,2 or even 1 days before your period is due, get a negative result and yet still be pregnant. For this reason if you do get a negative result then you should repeat the test a few days later.

The second disadvantage is that as these tests are reacting to such tiny amounts of hCG, the actual results may be very difficult to interpret as the test line may be extremely faint. I know that when I got a positive result six days before my period was due it was so faint as to be almost invisible and it took a lot of squinting along with manipulating a photo with imaging software before I could be sure. Of course as I approached and passed the date my period was due these lines darkened significantly, but it was still very difficult to read the original test. A third disadvantage isn't really that much of a big deal, unless you have suffered previous losses and that is that a very early positive result will add up to a week of extra worry on top of what you would have had if you had waited until you had missed a period to test. Getting an early result does not mean that you can have a reassurance scan any earlier, you still have to wait until you are 6/7 weeks, as before that time it's unlikely that there will be a heartbeat.

The final disadvantage is probably the most significant, and the most heartbreaking. It is a very harsh statistic that up to three out of four pregnancies will fail, with the majority of those failures occurring before the period is due. This particular type of miscarriage is known as a chemical pregnancy and in the days before early pregnancy the woman would not have even known she had been pregnant, with the bleeding corresponding with her normal period (or maybe a couple of days late). With the more wide spread use of these early tests, more women are having the heartbreak of getting a very faint positive, believing they are pregnant and then having their period show up as normal. What is even more heartbreaking is that the most regular users of these early tests are woman who are desperate to have a baby, women who chart their temperatures and ovulation and invest a huge amount of emotions, time and money to trying for that second line.

So while these early pregnancy tests do work, they also have a major disadvantage. I have to admit that even though I knew the statistics with chemical pregnancies, I still used early tests to check if I was pregnant almost a week before my period was due. But seeing as I had bought some super cheap tests of Amazon (10p/each) I then continued to test to ensure that the lines darkened and did not allow myself to fully believe that I was pregnant until the day my period was due. Making a recommendation as to whether you should use early tests to test for pregnancy is a difficult task. Personally they were right for me as I knew all the pros and cons, felt I could deal with knowing about a chemical pregnancy and was able to start the ball rolling for the extra care I would need in pregnancy a little earlier, but only you can decide if they are right for you.