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How quickly can you tell if you are pregnant?

Finding out if you are pregnant can be an exciting but anxious time. Many women want to know as early as possible if they have conceived. Here is a guide to the earliest signs and symptoms of pregnancy and how soon you can get an accurate result from a home pregnancy test.

How soon can you detect pregnancy?

The earliest signs of pregnancy are missed period, nausea, fatigue and breast changes. However, these symptoms can be very similar to those you experience before your period. So when can you reliably confirm a pregnancy?

Earliest pregnancy symptoms:

  • Missed period: One of the first signs of pregnancy is a missed menstrual cycle. You should miss your period by the time you are 4 weeks pregnant.
  • Nausea: Feeling sick and vomiting affects over half of all pregnant women. It often starts around 6 weeks but can begin as early as 4 weeks.
  • Fatigue: Feeling tired is common in early pregnancy due to rising progesterone levels. It may start from just 2 weeks pregnant.
  • Breast changes: Your breasts may become swollen, sore or tingly 1-2 weeks after conception as early pregnancy hormones stimulate growth.

While these symptoms may indicate pregnancy, they can also occur before your period due to hormonal fluctuations. The only way to confirm pregnancy is by taking a test.

How soon can a pregnancy test detect pregnancy?

Home pregnancy tests check for the presence of human chorionic gonadotropin (hCG) hormone in your urine. This hormone is only produced during pregnancy. Most tests can detect hCG as early as 6 days before your missed period.

Here is a guide to how early pregnancy can be detected:

Weeks pregnant hCG level Test result
1-2 weeks 0 – 50 mIU/ml Negative
3 weeks 5 – 50 mIU/ml Negative
4 weeks 5 – 426 mIU/ml Positive

As you can see, hCG levels are generally too low to detect pregnancy until after a missed period, around 4 weeks. However, some highly sensitive tests can detect hCG as low as 10 mIU/ml and may give a positive result earlier.

When to take a pregnancy test

  • 4 weeks pregnant/2 weeks after ovulation: This is often the earliest a test can detect pregnancy with an accurate result. Use a sensitive test.
  • 1 week after missed period: HCG levels double every 2 days. Waiting 1 week after your missed period ensures test accuracy.
  • Anytime if symptoms: Take a test as soon as you notice possible pregnancy symptoms.

How accurate are early pregnancy tests?

Most home pregnancy tests claim to be over 99% accurate from the day of your expected period. However, accuracy depends on several factors:

  • Test sensitivity – tests that can detect lower hCG levels are more accurate earlier
  • Using first morning urine – hCG levels are highest at this time
  • Following test instructions – to avoid false negatives/positives
  • Avoiding certain medications – some meds can affect results

The accuracy of pregnancy tests also increases with time as hCG levels rise. While a test can detect pregnancy around 4 weeks, it will be more accurate if taken 1-2 weeks after a missed period. Always re-test if you get an unexpected negative result.

When to see a doctor

While home pregnancy tests are very accurate, you should make an appointment with your doctor to confirm the pregnancy if your at-home test is positive. Your doctor can perform a quantitative hCG blood test and ultrasound scan to date the pregnancy and check it is developing normally.

See your doctor as soon as possible if:

  • You have a positive test but pregnancy symptoms do not progress
  • You have negative tests but think you may still be pregnant
  • You have abdominal pain, bleeding or other concerning symptoms


In summary, the earliest symptoms of pregnancy may start 1-2 weeks after conception. However, you cannot confirm pregnancy until taking a test. Modern home pregnancy tests can detect low levels of hCG to give an accurate positive result around 4 weeks pregnant, often 2 weeks after ovulation or 1 week after a missed period. While a positive home test is fairly conclusive, it is still recommended to see your doctor to confirm the pregnancy, check for complications and begin prenatal care.