Jul 6, 2022 - Technology

Why there's no quick fix for early pregnancy detection

Animated illustration of a pregnancy test with a screen that says loading

Illustration: Natalie Peeples/Axios

As states across the U.S. pass restrictive abortion laws with cutoffs as tight as six weeks, early pregnancy detection could give people more time to make the right choice for them.

Yes, but: Early home pregnancy testing tech is limited by human biology.

Why it matters: Taking a home test is typically a person's first step in confirming a pregnancy, followed up by blood work.

  • Given how pregnancy time is calculated, a six-week abortion ban can in practice give people as little as a week or two to make a decision about whether to terminate a pregnancy — assuming they can access such services, if they choose.

The details: Many home pregnancy testing companies offer "early detection" options, though they're typically less reliable than traditional home tests.

  • One manufacturer, Clearblue, says its early test can spot 71% of pregnancies five days before an expected period — compared to more than 99% from the day of an expected period.
  • Fertility startup Proov recently unveiled an "Early Check" pregnancy test, though its use is also limited to five days before an expected period.
  • Such tests also rely on a person's knowledge of their cycle, yet it may be getting riskier in some states to track such data. Plus, cycles can vary widely based on all sorts of factors, and people who aren't planning to get pregnant may not test before missing a period.

The challenge? Biology.

  • Home pregnancy tests check urine samples for the pregnancy hormone hCG, but it can take weeks between the time a person has sex and the point at which their body is producing enough hCG to be detected.
  • The pace of the early pregnancy process can vary widely among individuals, and even for one individual for different pregnancies, says Mayo Clinic doctor Leslie Donato.

Laboratory testing, Donato says, is far more accurate than at-home urine tests.

  • "If you were to send a blood sample to a lab, most laboratory tests would actually detect that pregnancy at the first day of missed menses," Donato says. "But some over-the-counter urine pregnancy testing may actually miss it. The over-the-counter tests are very clear about that. They say if you test too early, you can get a quote-unquote false negative, which is not really a false negative — you're just testing too early for the sensitivity of the test."

But blood testing is often more expensive and harder to access — a problem that may worsen in states where clinics are closing and some people may feel less safe seeking abortion care.

  • "Something as simple as going in for a lab draw can sometimes be a limitation for people, especially if they have to drive a long distance to get there, or if there are capacity issues wherever their laboratory is," says Donato.

The bottom line: There's no perfect early detection home pregnancy test on the horizon. People seeking to maximize their decision-making window should understand the limits of what's on the market.

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