For more than 30 years, DIY pregnancy tests have been the first hint for women about whether or not they are expecting. And now they may also have the power to reveal how far along the pregnancy is.
Here’s how it works. The Clearblue Advanced Pregnancy Test with Weeks Estimator contains two strips instead of the standard single strip. Both strips measure a hormone women produce when they are pregnant, called human chorionic gonadotropin (hCG), that appears after fertilization. hCG levels increase significantly in a woman’s urine during the early weeks of pregnancy, and start to decline 11 weeks into the pregnancy. Like standard pregnancy tests, the new one measures hCG levels. But the second hCG detection strip uses the hormone to estimate the length of the pregnancy based on time since ovulation. If a woman is indeed pregnant, the test will read: “Pregnant,” as well as list either: 1-2, 2-3 or 3+ to indicate by how many weeks.
The test is already available for women in Europe, where Clearblue launched it in 2008. The Food and Drug Administration approved the kit for market in December 2012, and starting September 1, the test will have widespread availablity to American women in all major retailers. Clearblue’s clinical trials included 2,000 women and 5,000 tested urine samples and determined that hCG measurement was effective and accurate for estimating the time since a woman’s last ovulation. The company says the test is 99% accurate at detecting pregnancy from the day of a woman’s expected period, and about 93% accurate in estimating the number of weeks.
“Through our consumer research, we found consumers were really wanting more information at the beginning of pregnancy. In fact, 78% of women in our research study feel that knowing how far along you are at the beginning of pregnancy is very important,” says Ryan Daly, the Marketing Director at Procter & Gamble, which makes the test. “We’re excited to bring this to the U.S. because there is nothing else like it. Consumers have been looking for more information and answers in the pregnancy test category and there hasn’t been any innovation since the digital pregnancy test was launched.”
To estimate how far along a woman is, doctors typically work off the date of her last menstrual period, as well as an ultrasound reading to document physical changes in the womb that can date a pregnancy. But not all women keep accurate track of their periods, and many have irregular cycles, so these dates aren’t always reliable for dating pregnancies. Ultrasounds can improve on the accuracy, based on doctors’ assessments of the baby’s development, but these images typically aren’t useful until the woman is at least eight weeks along.
The new test is not meant to be used as a substitute for these doctor’s methods, since ultrasound imaging is the gold standard for dating pregnancy. But the home-based test could be helpful and reassuring for women until they are able to get a confirmation from their physician. “We are living in an era where everyone wants an instant and immediate answer and have as much information as they can get, says Dr. Rebecca Brightman, an OBGYN at Mount Sinai School of Medicine in New York. “There are certain women with underlying medical problems or behaviors that I would like to see sooner rather than later for pre-pregnancy counseling. The more information I can get the more it helps me as a clinician.”
The test may be more helpful for certain groups of women and their doctors; for those who have irregular period, for example, it could pinpoint the timing of a pregnancy more accurately in the period before ultrasound can be used. “I think some patients [for] who have really irregular periods [it] might be helpful, but I think that for most women who have regular monthly periods, I don’t think it is going to give them a lot more information,” says Dr. Christine Proudfit, assistant professor, Department of Obstetrics and Gynecology at NYU Langone Medical Center.
There’s also some debate over how predictive hCG levels are in dating pregnancy. Its levels can fluctuate in the first weeks of gestation, and even remain low in some women. That’s one reason why doctors–and Clearblue–say it can’t replace an ultrasound and clinical diagnosis. “Earlier on in pregnancy, there’s a much narrower range of hCG levels, but as pregnancy progresses, there becomes a much wider range. Using it to actually date a pregnancy is much more challenging once you’re a few weeks along, which is usually about when we actually see patients,” says Proudfit.
For some, the value of the new test may simply be historical. Women treasure their tests as reminders of their first steps toward parenthood, and pregnancy tests themselves have experienced an interesting evolution. “As infertility became more of a part of the national conversation in the 1990s, I think the pregnancy test [took] on a different kind of symbolism. It’s not seen as just for teenagers or college students or unmarried women,” says Sarah Leavitt, who authored an extensive history of the pregnancy test when she was a historian at the National Institute of Health (NIH).
However women end up using the latest version of the test, most doctors say the additional information it can provide is a welcome addition, and hope it will prompt women to seek prenatal care sooner rather than later, which can improve their chances of having a healthy pregnancy as well as healthy children.