Guangzhou Wondfo Biotech is recalling 58,000 pregnancy tests from the U.K. after learning some devices delivered false positives.
The recall affects one lot of Clear & Simple digital tests manufactured last year that may erroneously inform the user that they are pregnant.
Guangzhou Wondfo attributed the false positives to a manufacturing fault.
In its urgent field safety notice, Guangzhou Wondfo outlined how the use of components close to the lower limit of acceptance led to "a large gap between the test strip bracket and the plastic enclosure" of the device. This gap resulted in "a change in the light path ... which eventually led to a larger signal value resulting in false positive results."
The problem manifested in the digital display of the device reading "Pregnant" despite the test strip inside the device corresponding to a negative result. Users of online parenting forums have been discussing the problem for months and taking devices apart to show the difference in the results of the underlying test strip and digital display.
Healthpoint, which distributes the Chinese-made test in the U.K., stressed that "very small numbers" of tests in the affected lot produce inaccurate results. However, the entire lot is being pulled from the market and 15,000 devices have already been quarantined or returned, The Guardian reports.
The MHRA learned of the fault almost one month before it or the distributor of the device told consumers about the problem. Officials at the agency said the delay was needed to give them time to assess the situation.
"When MHRA received the notification from the manufacturer we began our own internal processes to clarify the situation, including working out the magnitude of the issue and potential risks to public health. At MHRA we need to make sure our response to any report of device faults is proportionate and pragmatic," the agency said in a statement to British media.
The recall is not the first time a manufacturer has pulled a pregnancy test from the market over the risk of inaccurate results. Unipath withdrew 80,000 tests from the U.K. around a decade ago after learning some devices delivered false negatives. Last year, concerns about the accuracy and reliability of home pregnancy tests prompted a review by Australian regulators, leading to multiple recalls.