Could Having Two Periods in One Month Affect the Accuracy of a Pregnancy Test?

Family Medicine, Primary Care Roots Community Health Center, Hippo Education, Kameda Medical Center

Supervised by Kenji Taylor, MD

Having two periods in one month does not change a pregnancy test’s ability to work, but it can make it tricky to know when to take the test for the most accurate result.

Explanation

When you have two periods in one month, it usually means your cycle is irregular. Pregnancy tests look for a hormone called hCG that the body makes when a baby starts to grow. The test is most accurate when taken after your period is missed. With an irregular cycle, you might be unsure which period is the “real” one and when to expect a missed period. This uncertainty can lead to taking the test too early, which may show a false negative because not enough hCG is in your urine yet. Here are a few steps to help:

Note any changes in your cycle and document dates of bleeding.
Wait a few days after what you think is your missed period before taking the test.
If the test is negative but you still suspect pregnancy, repeat the test later.

If you’re confused about your cycle or need more guidance, it’s a good idea to talk with a healthcare provider. They can help determine the best time for testing and check if there are any underlying issues with your menstrual cycles.

(References)

Cooney MA, Buck Louis GM, Sundaram R, McGuiness BM, Lynch CD. Validity of self-reported time to pregnancy. Epidemiology. 2009 Jan;20(1):56-9. doi: 10.1097/EDE.0b013e31818ef47e. PMID: 19057382; PMCID: PMC4226997.
Cole LA, Khanlian SA, Sutton JM, Davies S, Rayburn WF. Accuracy of home pregnancy tests at the time of missed menses. Am J Obstet Gynecol. 2004 Jan;190(1):100-5. doi: 10.1016/j.ajog.2003.08.043. PMID: 14749643.
Nobles J, Cannon L, Wilcox AJ. Menstrual irregularity as a biological limit to early pregnancy awareness. Proc Natl Acad Sci U S A. 2022 Jan 4;119(1):e2113762118. doi: 10.1073/pnas.2113762118. PMID: 34969843; PMCID: PMC8740731.

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