How Soon Can You Take a Pregnancy Test & Assume Accuracy?

How Does a Pregnancy Test Work?

Pregnancy tests detect the presence of the hormone called human chorionic gonadotropin, aka hcg. This starts to be produced by placental cells around day 6 after fertilization when the embryo attaches to the uterus. Your hcg levels will double about every 2-3 days. In order to see a positive urine pregnancy test your hcg levels typically have to be at least 20mlU/ml. Often you will start to feel the early signs of pregnancy before your hcg levels are high enough to get an accurate positive pregnancy test.

What are the Early Signs You Might Be Pregnant?

• Spotting or light bleeding: 1/3 of women will experience implantation bleeding or light spotting when the embryo attaches into your uterus.
• Abdominal pain or cramping: this can sometimes feel similar to your menstrual cramping
• Higher basal body temperature: Your body will produce a spike in basal body temperature when you ovulate but will stay elevated if you are pregnant. Otherwise your body temperature will drop shortly after ovulation.
• Missed Period: This is usually the sign that most people start realizing they are pregnant.
• Tired: as progesterone levels increase to support your pregnancy many women begin to feel fatigued and tired.
• Nausea/vomiting: these symptoms can start 2 weeks after conception around 4 weeks of pregnancy. It can happen at any time of day, although many refer to pregnancy nausea and vomiting as morning sickness.
• Bloating and constipation: your hormones again are the reason for these symptoms. They cause your digestive system to slow down leading to the bloat and constipation.
• Breast Tenderness, Swelling or Tingling: With increasing estrogen and progesterone levels breasts can become tender, swollen, or tingly before your missed period.

Other symptoms: more frequent urination, mood swings, headaches, back pain, dizziness or fainting.

The Earliest You can See a Positive Pregnancy Test

It all comes down to hcg levels when you calculate when to take a pregnancy test. As soon as 8 days after conception your hcg levels are typically high enough that you can see a positive pregnancy test. This can be hard to determine unless you have been tracking your ovulation. Your egg will only be viable for 12-24 hours after ovulation so that can help guide you to about the most accurate conception date. Eight days after conception is usually around 3-5 days before your missed period.

If you have not been tracking your ovulation cycle it is difficult to calculate when to take a pregnancy test for the best accuracy. It is best practice to wait until after your first day of a missed period otherwise you may have a false negative due to hcg levels being too low. If you do decide to take a pregnancy test prior to your missed period and it is negative take another test 1-2 weeks later to ensure accuracy.

It is best to take a pregnancy test early in the morning when your urine would be most concentrated to get the most accurate results and ensure your sample is not overly diluted.

Could a Positive Result be Wrong?

This is less common than a false negative. Hcg is usually only present when a woman is pregnant so you would only have a false positive for a few different reasons. A positive pregnancy test may not always mean a viable pregnancy. Some examples include: a very early miscarriage, ectopic pregnancy, user error or expired test, positive due to fertility medications, or certain medical conditions. So if you have a positive pregnancy test you should always confirm with a physician that you have a positive pregnancy that is maturing in your uterus. This is often confirmed by an ultrasound around 8 weeks of pregnancy.

Which is the Best at Home Pregnancy Test?

Many at home pregnancy tests make a lot of claims about how early you can get results, but which is the most accurate test? This particular study looked at popular at home pregnancy tests on the market. These two tests were the most accurate tests on the market at the time.

First Response Early Results can show a positive pregnancy test with less than 6.3mlU/ml with 95% accuracy on the day of a missed period. It is also quite difficult to misread the results as it clearly states “pregnant” or “not pregnant” on the test stick next to the lines you should see for each result.

Clear Blue Easy Earliest Results can detect a positive pregnancy test at 25mlU/ml with 80% accuracy at the first day of a missed period.

Next Steps

This can be a really stressful time regardless of what you would like the outcome to be. If you do have a positive pregnancy test reach out to your OBGYN or find an OBGYN/midwife to confirm your pregnancy around 2 months after conception to ensure proper prenatal care and that fertilized egg is maturing in your uterus and discuss any other options you may have.