There are two ways to check for pregnancy using blood: a quantitative and qualitative HCG test.

  • A quantitative blood test measures the exact amount of HCG present in the blood.
  • A qualitative test detects whether HCG is present or not.

Blood testing has some advantages.

It allows for early pregnancy detection, and it can measure HCG concentration.

However, it is more expensive, the results can take time, and the test must be completed in a medical office.

When can I take it?

The earliest time for taking a home urine test is 14 days after possible conception, but waiting until a missed period will give a more reliable result.

Some tests on the market can be taken earlier. This depends on how sensitive they are.

It is important to read the package insert to know the best and earliest time to take the test.

The best time of day to take a urine pregnancy test is first thing in the morning, after waking.

This is because consuming a lot of liquids before taking the test, can lead to a false negative, even if the female is pregnant.

What happens next?

Used correctly, a urine pregnancy test should be around 99 percent accurate. However, incorrect use can result in an inaccurate reading.

A positive home pregnancy test simply means that HCG is present in the urine, while a negative test can have a variety of meanings.

Negative tests can mean that there is no pregnancy, or they can mean that the test was either taken too early to detect HCG, or that it was not done correctly.

If the result is positive, the female should make an appointment to see a healthcare professional, who can guide her about the next steps.

If the result is negative, but the female has the signs and symptoms of pregnancy, she should test again after 1 week or ask a doctor about a blood test instead.

Some modern pregnancy tests and kits can give an estimate of the conception date and consequent due date. However, this information is not always accurate.

Can medications affect the result?

Some medications can affect a pregnancy test’s accuracy.

These include:

  • Promethazine, used to treat certain allergies
  • Parkinson’s disease medication
  • Sleeping tablets
  • Some antipsychotics, including chlorpromazine
  • Opioids, for instance, methadone
  • Tranquilizers
  • Anticonvulsants, including epilepsy treatments
  • Infertility medication
  • Diuretics

Alcohol in the blood stream does not affect the pregnancy test because it does not interfere with the measurement of the hormone levels.

However, anyone who is trying to or expecting to become pregnant should avoid alcohol, as it can affect fetal development. Drinking during early pregnancy can increase the risk of miscarriage, premature birth, and low birth weight.

Other factors that affect HCG

Sometimes, there may be a positive test result but the female is not pregnant. High HCG can also indicate that some health condition has increased levels of the hormone.

This could be:

  • a deficiency of immunoglobulin A (IgA), an important antibody in immune function
  • gestational trophoblastic disease, a rare, pregnancy-related tumor
  • gestational trophoblastic neoplasms, a rare uterine tumor

HCG can rise as a result of some types of cancer. These are transitional cell carcinoma of the bladder and urinary tract, prostate cancer, renal cancer, and cancers of the gastrointestinal system. A pregnancy test may be used to assess for these.

Pregnancy tests are available at drugstores, pharmacies, and some convenience stores. Home pregnancy tests can be purchased for as little as a dollar, and some health centers offer them free of charge.