Pregnancy Signs and Symptoms: How to Tell If You're Expecting
For people who are trying to conceive, or people worried about the effectiveness of their birth control, knowing with certainty whether or not you're pregnant can be a massive source of stress.
Many new parents make the mistake of testing too early, leading to false negatives (or in some cases, false positives). This is especially true because many home pregnancy tests on the market advertise accuracy up to the first day of your missed period—and some claim to have accurate results before that!
So, how early can you really know that you're pregnant?
Let's take a look at the science of pregnancy hormones
As we know from biology lessons, during conception, sperm successfully enters the egg to start the development process. This process can occur anywhere from a few hours up to five days after having sex or receiving artificial insemination.
So what's with the delay? This time frame depends on ovulation (the process by which the ovaries release eggs to be fertilized, part of the female body's natural reproductive cycle). If ovulation has already occurred, the sperm finds an egg ready and waiting. If ovulation happens later, it can take a while for the process to get started.
When conception begins, the body starts to produce a hormone called human chorionic gonadotrophin (HCG), which only appears when you're pregnant. As the early days of pregnancy begin, HCG is produced and the amount of it increases quickly, sometimes doubling or tripling in a single day. This hormone is what home pregnancy tests look for to determine their results.
How do home pregnancy tests get their results?
A home pregnancy test bases its positive or negative on the presence of HCG in your urine. However, HCG needs to be present for the test to catch it. Therefore, if we test too early, we may get a false negative simply because the body hasn't had enough time to start producing HCG.
Check the packaging to find out the best time to take your test. Some highly-sensitive tests may be able to detect a pregnancy four or five days before your period is due (but the accuracy of these tests tends to be lower than those used after you've definitely missed a period).
It's also important to follow the directions carefully, especially the time limit given for accurate results. Some tests say to view the results between, say, three and ten minutes. This means a result viewed at two minutes is just as inaccurate as a result viewed at twelve. Looking too early or too late can result in false negatives, or a form of false positive called an "evaporation line."
What happens if I take the test too early?
Some of the most sensitive home pregnancy tests can test for HCG as early as eight days after conception. However, you're more likely to find tests that advertise results as soon as the first day of a missed period—and remember, there needs to be enough HCG present for the test to find it. Therefore, if you take a pregnancy test too soon after conception (sometime in that five hour to five day window, or just after it, when the body hasn't started to produce HCG), you could get a false negative.
Because of this, most home pregnancy tests recommend waiting to test until after you've missed your period. This time window could start on the very first day, or a few days after, if your period is irregular. It all depends on the amount of time your body has had to produce HCG.
Okay, but how do I know for sure?
If you're questioning the results of a home pregnancy test, your best bet is to make an appointment with your doctor. A doctor can test your blood or perform an ultrasound, two processes that are much more accurate than a home pregnancy test. Although the products on the market offer an impressive amount of accuracy, the best way to get that sense of certainty is through a doctor's visit.
In general, it's best to wait to take a pregnancy test until you're sure you've missed your period. This could be a day after you expected the start, or a few days later. The wait can be excruciating, but the longer you wait, the more accurate your results are bound to be.
Resources— Lamaze, WeHaveKids, NHS
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