Blood Testing vs. Urine Testing for Pregnancy: Which Is Right for You?

on June 19th, 2023
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in Health Information and Tips

Taking a pregnancy test is recommended if you suspect you might be pregnant. 

Even so, you must make the right decision on the appropriate test. Both urine and blood tests evaluate the presence of Human Chorionic Gonadotropin (HCG) in urine or blood samples.

Interestingly, manufacturers claim test kits give a 99% accuracy or more, which is not always true. While a urine test is widely available and can be used by anyone, a doctor primarily administers a blood test.

More importantly, the accuracy level of each test varies under different circumstances. It is, therefore, important to always consult a physician if you’re looking to check your pregnancy status, who can be instrumental in prenatal care.

Here’s what you need to know.

Comparing the Accuracy: Which Pregnancy Test Method is More Reliable?

Accuracy Levels of Blood Tests for Pregnancy

If you’re trying to conceive or suspect you might be pregnant, you may wonder if a blood test can be wrong. The good news is that a blood test done at a doctor’s office is over 99% accurate.

A blood test confirms pregnancy by checking your blood for human chorionic gonadotropin (hCG) that significantly increases after conception. The HCG hormone frequently doubles a few days after conceiving.

More importantly, you must wait the recommended time before taking it to boost its accuracy levels. Usually, the best time to take a pregnancy test is when your period is late. If your period is irregular or you don’t have a period chart, take the test after the most prolonged period cycle has passed.

Another biggest concern is whether you can have a negative HCG blood test but still be pregnant. Well, that is a possible but rare scenario. The false-negative result occurs if the test is done too early or faulty.

Accuracy Levels of Urine Test for Pregnancy

Most home pregnancy tests (urine tests) claim to be 99% accurate. However, there are disparities based on the timing and sensitivity of the test variety. A urine test detects HCG hormone from your urine sample.

While most pregnancy tests claim a 99% accuracy level or better, the claim doesn’t hold water if you take the test as early as the day you missed your periods. The disparity occurs because the amount of HCG varies each day after conception.

It is also difficult to detect a pregnancy using a urine test for someone who recently missed their period.  Studies suggest that most tests are not sensitive to detecting HCG a day or two after a missed period for early pregnancy detection.


Convenience and Cost: Pros and Cons of Blood and Urine Pregnancy Tests


Pros of Blood Pregnancy Test

A blood test is primarily used in a doctor’s office if there’s a potential issue with your pregnancy. It may also be needed if there is a complicated factor—e.g., multiples requiring greater sensitivity in a blood test.

A doctor may also order a blood test for a high-risk pregnancy. A physician may also request the examination during fertility treatment or after a negative urine test and the period hasn’t come. A blood test can help confirm miscarriage or diagnose potential tubal pregnancy and other complications.

Here are a few pros you should know about;

  • Early Detection: A blood test can detect a pregnancy days before a missed period— 6-8 days after you ovulate. On the contrary, a urine test detects pregnancy 12-15 days after ovulation if you have a 28 day cycle.
  • Quantitative Assessment: Besides detecting a pregnancy, a blood test assesses the level of HCG hormones in the bloodstream. As a result, the physician can use the readings to track the health and viability of the pregnancy.
  • Enhanced Accuracy: Blood tests have better accuracy levels compared to urine tests because they detect HCG in the bloodstream, compared to a urine test. It’s, therefore, an ideal method for caring for high-risk pregnancies.

Cons of a Blood Pregnancy Test

  • Results Take Longer: Although you can take a blood test earlier than a urine test, it takes longer to receive results. The timing of test results varies from one lab to the next, ranging from an hour to a few days.
  • Location: A blood test is administered in a doctor’s office, taking more time from your schedule. 
  • Slightly Painful and Scary: If you hate needles, a blood test might make you nervous.
  • Cost: A blood test typically costs more than a urine test. You can pay as much as $50 compared to a urine test which costs as little as a few dollars. A blood test is expensive because it is slightly more sensitive than a urine test. It means you can get an accurate answer early in the pregnancy—typically 7-10 days after conception.

Pros of a Urine Pregnancy Test

If you don’t have time to schedule an appointment with your physician, an at-home pregnancy(urine test) can be the first step in knowing if you’re pregnant.

Here are some of its advantages;

  • Availability: You can find urine test kits in the most convenient stores. More importantly, you can buy them in-store or online without a prescription.
  • Urine Test is More Affordable: Urine tests cost less than blood tests. Some packages come with several dip sticks of test strips, enhancing your value for money. 
  • Convenience: You can do the test in the privacy of your home at your convenience. With online ordering, you don’t have to be seen in an online store if you’re uncomfortable.
  • Get Results Within Minutes: If you’re excited to know if you’re pregnant, a urine test will let you know within minutes. The quick results can help you make lifestyle changes, such as quitting alcohol or modifying your diet as quickly as possible.

Cons of Urine Pregnancy Test

  • The Tests Have a Short Span: If you let the test sit too long, the urine on the strip can dry up and make it look like two lines instead of one. The best way to avoid the scenario is to read and follow the instructions.
  • False Positive and False Negative Results: Although urine tests are generally reliable, they may generate inaccurate results. Early testing, hormonal disorders, and medication can interfere with the results.
  • It Has Low Sensitivity: A urine pregnancy test is less sensitive than a blood test because it requires slightly more HCG (Human Chorionic Gonadotropin) for a positive reading.

 Saving Money on Pregnancy Tests

One way to save money is to take the test by choosing the right time. If you do it too early, the results may not be accurate, and you may need to retake it, deeming it expensive. So, waiting a few days may give you accurate results and eliminate the need to repeat the test, driving the cost upwards.

Similarly, avoid buying pregnancy tests in bulk because they have expiry periods. However, you may need to buy a few more for a confirmatory test.

When to Take a Pregnancy Test: Factors to Consider Before Choosing a Testing Method

Some pregnancy tests can detect a pregnancy before your period is due. Even so, waiting to allow the human chorionic gonadotropin (hCG) hormone levels to build up for an accurate result is always advisable. 

Taking the pregnancy test before a missed period increases the risk of a false negative.

So, how soon should you take a pregnancy test?


The Best Time to Take a Pregnancy Test

It’s always advisable to wait at least one day after a missed period to take the test. Taking the test a week after the missed period increases your chances of getting an accurate result. 

Remember, a pregnancy test assesses the hCG hormone levels, whose production starts after conception. More importantly, the body releases the hCG hormone after implantation— when a fertilized egg attaches itself to the uterus.

The implantation occurs 10 days after conception— when sperm meets a fertilized egg. Then, traces of hCG occur 6 days after conception. However, it takes 7-10 days after implantation for the body to build up enough hCG to show up on the test.

Therefore, if you have an irregular period, it’s best to take the test 21 days after having unprotected sex. If you test too early in your cycle, you’ll likely get an inaccurate result.

Factors to Consider Before Choosing a Testing Method

  • Test Type and Collection Method: There are different types of pregnancy tests; some use sticks and other strips. Similarly, the collection method differs— some require you to pee in a cup, while others require placing the test strip in the urine stream. The type of test you choose depends on your preference and convenience.
  • Speed: If you’re eager to see the results, the faster the test kit, the better it is for you. Check the test kit instruction on how long you’ll wait for the results. Some home pregnancy tests can get the results in under a minute and up to five minutes. If you go to a doctor’s office, a blood test might take several hours and up to 3 days.
  • Cost: If you’re under budget, visit a dollar store to buy a test kit for as low as $5. A doctor’s office is another alternative; however, be prepared to pay a higher fee.
  • Number Per Package: If you’re trying to conceive and want to test regularly, consider picking a value pack. You may also want to buy a test kit or two if you simply want to confirm whether you’re pregnant.

Interpreting Results: Understanding How Blood and Urine Pregnancy Tests Differ

Understanding Blood Pregnancy Test

There are two types of blood pregnancy tests—qualitative and quantitative—both of which offer highly accurate test results. 

Qualitative blood serum tests detect the presence of hCG in the blood— similar to a urine test— which confirms or rules out pregnancy. On the other hand, there’s a quantitative blood serum test known as the beta hCG test. 

The quantitative test measures the volume of hCG in your blood. Owing to its ability to detect trace hCG in the bloodstream, it’s highly accurate, explaining its role in detecting pregnancy loss and complications.

A doctor is likely to order a blood test for the following reasons:

  • A high-risk pregnancy
  • Fertility treatment
  • When urine results come out negative and the period hasn’t come
  • Confirm or rule out a miscarriage
  • Pregnancy complications
  • Diagnose tubal pregnancy

A typical result from a quantitative hCG blood pregnancy test shows hCG levels rising in the first trimester, declining at around 10 weeks, and stabilizing at 16 weeks and the remainder of the pregnancy.

Higher than normal hCG levels may indicate the following:

  • More than one fetus—twins or triplets
  • Ovarian cancer
  • Tumors on the uterus—not necessarily cancerous
  • An infection or malignant tumor on the uterus

On the contrary, lower than usual hCG may indicate:

  • Miscarriage
  • Ectopic pregnancy
  • A dead fetus

False Negative in Blood Pregnancy Test

A false negative doesn’t confirm pregnancy when you’re indeed pregnant. A false negative occurs if you test too early when hCG levels are too low to detect a pregnancy. However, obtaining a false negative after the pregnancy reaches 9-14 days is highly unlikely.

If, from your assessment, you believe you’ve obtained the false negative for testing too soon, the physician may recommend you retake the test after 48-72 hours. A false negative may also occur if you suffer from gestational trophoblastic disease. 

In that case, the lab technician may need to dilute the sample to get an accurate reading.

False Positive in Blood Pregnancy Test

A false positive means your test results read positive, confirming your pregnancy when you’re not. A false positive is rare; however, it may occur if you’re under medication containing hCG—such as fertility treatments, or due to other medical conditions.

Here are the possible causes of a false positive:

  • Presence of cancer cells in your blood
  • Kidney Failure
  • Blood or Plasma malfunction
  • Kidney failure
  • Presence of antibodies due to exposure to specific animal products

Understanding Results of Urine Pregnancy Test

The body only releases hCG when a fertilized egg implants in the uterus. In most people, this process takes place six days after conception. More importantly, hCG levels increase each day of the pregnancy and double up every two days.

A urine pregnancy test can effectively conduct a qualitative test of hCG and detect pregnancy a week after a missed period. Some urine tests can detect hCG as early as one day after a missed period; most are not sensitive to detect a pregnancy so soon.

The results of a urine test depend on their sensitivity—with a higher sensitivity translating to a faster result. Even so, if your blood has hCG from a recent miscarriage of fertility treatment, consider using a less-sensitive test kit.

A False-Negative Urine Test Result

If you obtain a negative result, meaning you’re not pregnant, you might still be pregnant— false negative.

A false negative result may occur for the following reasons:

  • Timing the Test Incorrectly: You should perform a pregnancy test 15 minutes after collecting your urine sample. It’s also essential to read the instructions on how long it takes to analyze the test results. If you check too soon, you’ll assume it’s negative; if you do too late, it could be a false positive.
  • Diluted Urine: Most at-home pregnancy tests suggest you take the test in the morning soon after waking up. Generally, urine is highly concentrated in the morning. If you take too much fluids before the test, you will likely return a negative test.
  • Performing the Test Too Soon: You’ll likely get a false negative if you complete a urine test immediately after missing your period. It’s also advisable to wait at least a day and up to 7 days after your period is due to improve accuracy.

If your periods haven’t resumed after a week following a negative result, consider taking another pregnancy test.

A False Positive Urine Test

If the lines indicate a positive test—even if faint— it means you’re pregnant. Although rare, you can obtain a false positive that tells you’re pregnant when you’re not.

The following are the reasons for obtaining a false positive:

Chemical Pregnancy: A chemical pregnancy means a fertilized egg implanted in the uterus, which did enough to trigger the production of hCG, but the pregnancy stopped developing. 30-50% of all pregnancies become chemical due to anomalies that halt further growth.

  • You used an expired urine test.
  • If you have traces of blood or protein in your urine
  • If you’re taking prescriptions containing hCG
  • If you’re currently taking diuretics

Try Newport Urgent Care Pregnancy Testing Services

A urine or blood test helps you find your pregnancy status. It’s also essential to pick the right one and appropriate variety to avoid inaccurate results. More importantly, a physician-supervised test leads to better health care for the unborn child and helps detect complications.

With that in mind, it’s advisable to speak to visit an urgent care center to administer your pregnancy test.

Newport Urgent Care Center & Occupational Medicine has a well-equipped laboratory and board-certified physicians ready to assist you.

Contact us online or call us at 949.806.4388 to book an appointment.