Causes of a Positive Pregnancy Test After a Miscarriage

How Long is a Pregnancy Test Positive After Miscarriage?

positive pregnancy test
How long does it take a pregnancy test to become negative after a miscarriage and what are some causes of a persistent positive hCG level?. AN HOOTON Science Photo Library/Getty Images

If you've had a diagnosis of miscarriage, you may be confused if you take a pregnancy test and find that it's positive. What does this mean? This is actually a common source of confusion with a few different explanations.

A Positive Pregnancy Test After a Miscarriage

In order to understand why you may have a positive pregnancy test even after miscarriage it's helpful to look at what pregnancy tests check.

Pregnancy tests work by detecting the presence of the pregnancy hormone hCG (human chorionic gonatotropin) in the blood or urine.

Most of the time hCG is only in a woman's body during pregnancy, so a test is usually fairly conclusive for pregnancy. (There are some rare ovarian tumors which secrete hCG, but these are extremely uncommon.)

However, after an embryo or fetus stops growing and a miscarriage occurs, the hormone does not disappear from a woman's body right away. The level of hCG gradually decreases, falling back down to zero over a period of days or even weeks depending on how far along the pregnancy was when the miscarriage happened.

Because today's pregnancy tests usually detect even very low levels of hCG, taking a pregnancy test in the days or immediate weeks after your miscarriage can still show a positive result. You may also continue to feel pregnancy symptoms after miscarriage, even when it is 100 percent certain that you have miscarried.

How Long Does it Take hCG (and Therefore Pregnancy Tests) to Return to Normal?

All in all, it takes an average of 12 to 16 days for hCG to disappear from the body, but this can vary based on how high your hCG level was at the time of your miscarriage. It can take around a week to return to zero with a chemical pregnancy (a very early pregnancy loss) and up to a month or even more with a miscarriage which occurs later in pregnancy.

Causes of a Persistent Positive Pregnancy Test After Miscarriage

Most of the time, your hCG level will return to zero in time as noted above. But what if you continue to have a positive pregnancy test and/or continue to have pregnancy symptoms?

If it has been more than a couple of weeks since your miscarriage, you should call your doctor if you are still getting a positive pregnancy test. In this situation, your doctor may want to monitor your hCG level with blood tests (a quantitative hCG.) If you continue to have a positive blood pregnancy test, there is a possibility that you could have an incomplete miscarriage, or even be pregnant again.

Could it Be An Incomplete Miscarriage?

If your hCG level does not return to zero within a reasonable time frame, there is a chance that there might still be pregnancy tissue in your uterus, even though a miscarriage did occur. This is known as an incomplete miscarriage. Unfortunately, it does not mean that your pregnancy is continuing or is viable.

You may need a simple surgical procedure called a D&C (dilation and curetage) to remove the retained products of conception, which is usually only small pieces of the placenta.

These tissues will probably be reabsorbed (broken down) by your body in time, but surgery can help put a stop to heavy bleeding sooner. Bleeding is a common symptom of an incomplete miscarriage.

Could You Be Pregnant Again?

If you have been sexually active and have a positive pregnancy test soon after a miscarriage, it is also possible that you might be pregnant again. Your doctor will be able to tell you for sure one way or the other, though she may need to follow you with blood hCG tests to know for sure.

Although many women are not aware of this, it's possible to become pregnant during your first menstrual cycle after a miscarriage.

 If you are not trying to become pregnant again so soon after your pregnancy loss, you should use contraception to prevent a pregnancy until you are ready.

Talking about getting pregnant can be painful after you've had a miscarriage. It's important, however, for those who would like to become pregnant again, to be aware of the myths. In the past it was thought that getting pregnant within six months of a miscarriage raised the risk of complications ranging from toxemia to stillbirth, and in fact, doctors often recommended that women wait. These concerns are simply not true.

There is not an increased risk of problems if women become pregnant shortly after a miscarriage. In fact, large studies done in 2010 and 2016 found that not only does getting pregnant within six months after a miscarriage not carry an increased risk, but pregnancy outcomes were better for those who became pregnant within six months compared to those who waited at least six months.

Molar Pregnancy

An uncommon cause of a persistent pregnancy test after miscarriage is a molar pregnancy—hydatidiform mole or gestational trophoblastic disease. Gestational trophoblastic disease is a term used to describe several conditions in which there is abnormal growth of placental tissue. Molar pregnancies are caused by chromosome abnormalities which arise during the process of fertilization, for example, when a sperm fertilizes an empty egg or when two sperm fertilize a single egg. These conditions can be benign or instead, become malignant, such as an invasive mole or choriocarcinoma. Even the most aggressive malignant forms of this disease are most often curable with treatment. Learn more about the symptoms and treatments for molar pregnancy.

A Word From Verywell

Experiencing a miscarriage can be an emotional rollercoaster and the confusion over a persistently positive pregnancy test can add to this already difficult situation. Be assured though that it can take a variable amount of time (on average two weeks) for a woman's hCG level to disappear after a miscarriage.

That being said, if you feel like something is just not right, especially if your bleeding from your miscarriage is heavy or persistent, or if you are experiencing worsening pelvic pain or a fever with your miscarriage, be sure to seek medical guidance.

Sources:

Kangatharan, C., Labram, S., and S. Battacharya. Interpregnancy Interval Following Miscarriage and Adverse Pregnancy Outcomes: Systematic Review and Meta-Analysis. Human Reproduction Update. 2017. 23(2):221-231.

Love, E., Bhattacharya, S., Smith, N., and S. Bhattacharya. Effect of Interpregnancy Interval on Outcomes of Pregnancy After Miscarriage: Retrospective Analysis of Hospital Episode Statistics in Scotland. BMJ. 2010. 341:c3967.

Shaaban, A., Rezani, M., Haroun, R. et al. Gestational Trophoblastic Disease: Clinical and Imaging Features. Radiographics. 2017. 37(2):681-700.

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