Home pregnancy tests have pretty much revolutionized the way couples discover they’ve got a baby on the way. As technology has evolved, those over-the-counter kits have become increasingly sophisticated. Some claim they can tell you you’re pregnant before you’ve even missed your period. Others say they can predict if it’s a boy or a girl, just a few short weeks after conception. UR Medicine fertility expert Dr. Wendy Vitek helps sort out the good ideas from the gimmicks.
Health Matters: First, can you give us a quick lesson in home pregnancy tests and how they work?
Vitek: Home or OTC (over-the-counter) tests are designed to detect human chorionic gonadotropin (HCG), a hormone produced in pregnancy. When your OTC pregnancy test results are positive, the test has detected HCG. While these tests are pretty good at identifying pregnancy, a positive result could occur for reasons other than pregnancy. For instance, there are some fertility treatments where women take HCG shots, which could create a false-positive test result. Also, there are HCG-secreting tumors that might lead to a positive test in the absence of a pregnancy.
Health Matters: So, how accurate are the test results from OTC pregnancy tests?
Vitek: Test manufacturers claim their results are accurate more than 99 percent of the time in detecting pregnancy on the first day a woman has missed her period. But independent studies of some popular brands of OTC pregnancy tests put their accuracy at 54 percent to 97 percent in that timeframe.
Health Matters: What about tests that claim they can detect pregnancy before a missed period?
Vitek: Some pregnancy tests say they can detect pregnancy up to five days before a woman’s missed period. If she has a regular menstrual cycle and becomes pregnant, detecting HCG in her urine five days before her missed period is possible, provided the test can detect very low levels of the hormone. However, test accuracy will increase as HCG levels rise so waiting until the first day of a missed period is less likely to lead to a false-negative test and may help a woman avoid the hassle and expense of taking multiple pregnancy tests.
Health Matters: Are some test more accurate than others?
Vitek: Some studies point to greater accuracy with digital tests over non-digital. Digital tests offer easier-to-read results, unlike the non-digital, which may require you to interpret results based on lines or colors. Digital tests tend to be more expensive than non-digital tests. Pregnancy tests range from $8 to $20 depending on the brand, number of tests in a kit, and if the test is digital.
Health Matters: So, once you’re pregnant, are there any at-home tests that can tell you if your baby is a boy or a girl?
Vitek: There are OTC gender identity tests on the market. These work by checking the ratio of hormones in a pregnant woman’s urine to determine the baby's sex. Some tests can be done after the 10th week of pregnancy and cost about $40. The accuracy of these tests isn’t clear, so I wouldn’t recommend using them to decide whether to paint the nursery pink or blue. If you want to know your baby’s sex, you’d be wise to wait until you have an ultrasound. When done after the 16th week of pregnancy, it’s an accurate way to determine sex. Also, new blood tests that screen for Down syndrome, which are recommended for women over age 35, can accurately detect the sex of the baby after 10 weeks.
Health Matters: Any advice or cautions to women who use OTC pregnancy tests?
Vitek: While home tests are certainly useful for many, nothing replaces a good relationship with your health care provider. If you believe you may be pregnant based on symptoms (such as a missed period, breast tenderness, fatigue, nausea), but your at-home pregnancy test is negative, you should contact your doctor for further testing.
Wendy Vitek, M.D., combines clinical expertise, kindness, and compassion with state-of-the-art technologies, caring for patients at UR Medicine’s Strong Fertility Center. A board-certified reproductive endocrinologist, she is director of the Fertility Preservation Program.