How Accurate Is a Pregnancy Test after a Miscarriage?

Repeat blood tests can be used to track the changes in hormone levels.
A pregnancy test after a miscarriage is likely to be a false positive.
The timing of a pregnancy test after a miscarriage is critical for accurate results.
Article Details
  • Written By: A. Pasbjerg
  • Edited By: Heather Bailey
  • Last Modified Date: 26 September 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
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The accuracy of a pregnancy test after a miscarriage can depend on a variety of factors. Women who were further along in their pregnancies will have higher hormone levels in their bodies than those who miscarried earlier, and those levels will take longer to drop. A test taken shortly after the miscarriage will be more likely to show a false positive than one taken later. Over-the-counter tests, which show positive or negative only, may be less accurate than a repeat blood test that shows actual hormone levels and how they are changing. In general, a pregnancy test after a miscarriage has a good chance of showing a false positive result.

Pregnancy tests show results based on the amount of human chorionic gonadotropin, or hCG, in the blood or urine. Levels of this hormone increase rapidly during early pregnancy, so the further along the pregnancy is, the higher the level will be. Therefore, women whose pregnancies have progressed further will tend to have more hCG, and it will take more time for their level to drop back to zero. Depending on the quantity of hCG present, it can take anywhere from a week to almost a month for a pregnancy test after a miscarriage to be accurate.

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Timing of a pregnancy test after a miscarriage is also critical for a valid result. Due to the variability in hCG levels women may have as well as individual differences in the rate they may drop, it can be hard to determine how soon after the pregnancy is lost that a test may come up negative. A test taken within the first week after a pregnancy loss will likely give a positive result since hCG levels will have had little time to drop; for some women, this may continue to be true for several weeks.

Different types of pregnancy tests may offer more accuracy than others when used after a miscarriage. Over the counter tests come with varying degrees of sensitivity to hCG levels in the urine, so one test may still read positive as hormone levels drop while others will stop registering them. For truly accurate results, the best option is often to have a series of blood tests so the results can be compared. These tests show quantitatively how much hCG is in the blood, so if the numbers decrease over time, it is typically a clear indication that a miscarriage has occurred.

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serenesurface
Post 3

@fBoyle-- Do you know if you ovulated during this time?

You can get pregnant after a miscarriage without getting a period first. But you can't get pregnant without ovulation which only occurs when hCG is down to zero. So that should tell you the accuracy of the test.

SteamLouis
Post 2

@fBoyle-- Three months is a long time, I'm sure your hCG levels would have gone down by then. You must be pregnant, you should make an appointment with your doctor.

I had a false positive pregnancy test three weeks after my miscarriage. My hCG levels went down only after six weeks.

I know that it takes longer for some women's hCG levels to drop, but it surely wouldn't take three months. False positives are usually one to four weeks after miscarriage. It took me more than usual, so six weeks.

fBoyle
Post 1

I had a miscarriage three months ago. I was only six weeks pregnant then. My husband and I went back to trying soon after the miscarriage and today I did a pregnancy test and it says positive.

What are the chances that it's a false positive?

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