4 March 2020

How soon after conception can I take a pregnancy test?

pregnancy test
Mireia Galian
CONSULTANT GYNAECOLOGIST
Mireia Galian
IVI London

 

The use of a pregnancy test is invariably surrounded by heightened emotion. Whether you are desperately keen to become pregnant after months of trying, or whether you are equally keen for reassurance that you are not pregnant, the test is never a matter of indifference. So it’s perfectly understandable that when you want to take that test, you will be anxious to know the soonest possible time that you can get your result. But you need to have a little patience. Given that an accurate result is just as important as a speedy one, it is essential to resist the temptation to take an early pregnancy test. As a rule of thumb, the first day of your missed period is about right.

Let’s take a look at why this is the case. We will cover how pregnancy tests work, how accurate you can expect the result to be and how the timing relates to your menstrual cycle.

How does a pregnancy test work?

There are different ways of testing for pregnancy, including having a blood test in a doctor’s surgery or specialist clinic, but for the moment we’re looking at over-the-counter packets that you can buy in a chemist or supermarket and take home. That way, when the time comes you can get your result in the privacy of your own surroundings.

Home tests all check for the presence of human chorionic gonadotrophin (hCG) in your urine. This is the pregnancy hormone which is produced by your body immediately after you have conceived. After the embryo attaches to the lining of the uterus, hCG is produced by the initial placenta (or trophoblast) and builds up fairly rapidly in your body, being present in both urine and the bloodstream. Even though it is detectable in very small concentrations, it takes some time for levels to build up for a reliable test result.

How do you take the pregnancy test?

Different brands have different methods of testing urine. Most advise that you should do the test first thing in the morning when your urine will be at its most concentrated. Some ask you to collect some urine in a receptacle and then dip a testing stick into it. With others, you need to collect the liquid and then use an eyedropper to place a small amount into a special container. Others work by holding the testing stick into the urine stream, so there’s no collection involved.

What does the pregnancy test result look like?

The way the result is presented also varies according to the brand. They will all tell you the length of time you need to wait before reading the result. This is then displayed either with a colour change, a line, a plus or minus symbol or even the words ‘not pregnant’ or ‘pregnant’.

How soon can I take the test?

The usual and long-standing advice is to wait until the first day of your missed period to allow enough time for detectable levels of hCG to build up. Nowadays some tests are more sensitive than others and you may be able to take the test as early as 4 to 5 days before your period is due. Check the instructions on the packet!

You probably won’t know the exact date of the suspected conception at this stage. This is because, although you can reckon roughly on ovulation taking place two weeks before the next period is due if your cycle is regular, an irregular cycle can mean that the exact date of ovulation is unpredictable. The advice of the NHS is that, if you are pregnant, you can assume that conception took place two weeks before your first missed period was due. They also have a pregnancy due date calculator so you can work out when the baby is due.

A blood test conducted by a doctor’s surgery or a specialist clinic can be carried out earlier than a home pregnancy kit. These can be taken 7 to 12 days after you conceive. However, unless you have a medical condition that makes an early pregnancy test essential, or you are engaged in a treatment with a fertility clinic, it is much more likely that a home kit is your most practical option.

How accurate will my pregnancy test result be?

Accuracy is the whole point of the number of days you need to wait. As long as you follow the recommended time, home test kits are generally 97% accurate. Some kits come with two tests so if you get a result you were not expecting, you can check again in a couple of days. It’s worth knowing that a positive test is almost certainly correct but that false negatives are slightly more likely. If you get a positive test result, you should consult your GP straight away.

A word of caution: some medications can affect the result and make it positive even though you are not pregnant. These include medications for allergies such as promethazine, medications for anxiety and anti-psychotics, diuretics, anticonvulsants and even some medications for infertility. Here too you will find a full list in the instructions in the packet. If in doubt you could ask a pharmacist.

Getting help when it’s needed

Congratulations if you get the result you were hoping for from your pregnancy test! But if you are among the small proportion of people who long for a pregnancy that never seems to happen, don’t wait too long before finding some help. Your GP may be able to refer you to a fertility clinic, depending on what is available from your local clinical commissioning group (CCG). The NHS publishes a guide to finding your local CCG.

If the services you need are not available, or waiting times are too long, you could get in touch with us at IVI. A positive first step would be to take a look at the video about our London clinic, or more positive still, come to one of our patient open evenings and see for yourself!

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