Taking a home pregnancy test can be daunting for both women who want to conceive and those not intending to. Knowing when to take a pregnancy test with an accurate result and avoiding an emotional roller-coaster is essential.
The best time to take a pregnancy test is to wait at least one week after the last missed period to allow enough time for the pregnancy hormone human chorionic gonadotropin (hCG) to increase. Taking a test upon waking in the morning can increase accuracy and reduce the chances of a false negative result in women with regular menstrual cycles.
This article looks at when the best time is to take a pregnancy test, what happens in those taking a test too soon and factors that can affect the test’s accuracy.
Pregnancy occurs when a sperm fertilizes an egg after its release during ovulation. This fertilized egg travels and attaches to the uterine lining, where implantation occurs. The placenta then forms and releases hCG into the bloodstream.
After implantation, the body takes approximately nine days after conception to produce detectable hCG levels in the urine.
Most pregnancy tests detect the presence of hCG in the urine when it reaches 20-50 mlU/ml, with some tests more sensitive than others. This means a lower hCG amount in the urine may produce a positive result in some tests and not others.
When Is The Best Time To Take A Pregnancy Test
Many pregnancy tests claim to be highly accurate, capable of detecting pregnancy from the first day of a missed period, and some even several days before.
However, waiting until at least one day after a missed period or one to two weeks after gives a more reliable result. To increase the accuracy, women can take a pregnancy test using the first urination in the morning when the urine is the most concentrated.
Apart from a missed period, pregnant women may also experience other signs and symptoms during early pregnancy that may warrant a pregnancy test, such as stomach cramps and breast tenderness or pain. Women who suspect that contraception has failed should also seek a test to determine or rule out pregnancy.
Types of Pregnancy Tests
Pregnancy is usually determined by detecting hCG either in the urine or in the blood. Urine pregnancy tests are qualitative tests, which means it detects urine hCG to indicate a positive or negative result. Blood pregnancy tests can also be quantitative to detect and monitor varying hCG levels during pregnancy.
Typically pregnancy tests refer to ones that women can use in their own home setting, while blood pregnancy tests often involve medical practitioners.
Urine Pregnancy Tests
Home pregnancy tests use antibodies to detect hCG in the urine as HCG levels increase rapidly during early pregnancy.
Most pregnancy tests are 99 percent accurate when taken after a missed period. Since the body only produces hCG during pregnancy, any positive result typically indicates a pregnancy.
A false-negative result indicates a negative reading on a test in a pregnant woman. The primary cause is taking a test too early after conceiving, before a missed period or too soon after a missed period. The placenta has had insufficient time to produce hCG to detectable urine levels, showing a negative result.
Repeating the test one week after a missed period may reveal a positive result after detecting sufficient hCG levels.
Not following instructions carefully on a home pregnancy test kit can affect results, as can checking results on a test strip too soon; both giving rise to a false-negative result.
False-negative results may affect how women take precautions towards their unborn baby, such as unknowingly taking other medications that can harm the fetus or continuing smoking or drinking alcohol.
Although rare, a false-positive result indicates pregnancy even though one is not present and can cause unnecessary alarm in women not intending to get pregnant.
False-positive results can occur in those taking fertility medication that contains hCG. These medicines may interfere with test results if they are used too close together in time.
Unfortunately, false-positives may also occur after a recent miscarriage soon after implantation occurs (biochemical pregnancy). Other reasons for false-positives include ectopic pregnancy, menopause or ovary complications.
Factors Affecting Accuracy
Although most home pregnancy tests claim to be more than 99% accurate when used from the first day of a missed period, studies show that this may not be entirely true when used in a home setting. The accuracy claimed is based on urine sample testing by qualified laboratory technicians under ideal conditions.
Here are some factors that may influence the accuracy of pregnancy test results:
- Menstrual cycle patterns affect the timing of ovulation and conception. According to the FDA, pregnancy tests can detect hCG in the urine 12-15 days after ovulation in women with a regular 28-day menstrual cycle. These women may take a pregnancy test from the first day after a missed period (although accuracy increases with a longer delay before testing).
- It can be trickier for women with irregular periods, and studies reveal that only 32% of women have regular monthly cycles. With irregular cycles, ovulation time is unknown, making it difficult to calculate the time of conception. So waiting at least one to two weeks after sexual intercourse will give a more accurate result before taking a test.
- Taking a test with the first urination in the morning increases accuracy as the urine is most concentrated. Despite this, women who drink large amounts of water should still show a positive test if pregnant. Diluting urine with water before taking a test may give a false-negative result.
- Fertility medication or drugs that contain hCG can interfere with the accuracy of results. Other medications, including oral contraception or antibiotics, generally do not affect test results.
- User-based errors can give inaccurate results. Some women may not follow pregnancy test instructions precisely enough or misinterpret results. Pregnancy test strips often reveal results with either one or two lines, a plus or minus sign or much preferred easy-to-read results such as “pregnant” or “not pregnant”. Studies show that one in four women can misread traditional line-based pregnancy tests to determine pregnancy.
Blood Pregnancy Tests
Under normal circumstances, a urine pregnancy test is sufficient to confirm pregnancy, but certain situations may warrant a blood pregnancy test.
A blood pregnancy test typically involves taking a serum blood sample and analyzing hCG content to determine pregnancy. Most blood tests are more sensitive than urine tests, which means they can detect a lower hCG level to confirm a positive result.
In addition, blood pregnancy tests can detect hCG levels in the body up to two to four days earlier than a urine test, so they may be of use in those wanting an earlier pregnancy confirmation.
When to Use Blood Pregnancy Tests
Healthcare providers may monitor hCG levels over time by using blood pregnancy tests in certain conditions, such as women carrying multiple babies or those at higher risk pregnancies.
Doctors can also use blood pregnancy tests to confirm or rule out pregnancy complications, such as ectopic or tubal pregnancy and women with persistent negative test results despite no signs of a period.
When to See a Doctor
Although home pregnancy tests can detect pregnancy, it gives no information as to viability. Women with a positive result should make an appointment with a healthcare provider to confirm pregnancy.
A doctor may want to measure hCG concentrations by suggesting another urine test or a blood test. Having an ultrasound can also confirm how far along a pregnancy is and may also be able to detect a fetal heart rate.
Women should contact their doctor after repeated negative results with no signs of a period. Sometimes, other medical disorders result in missed menstrual cycles, such as stress, thyroid conditions, and ovary complications.
Those who have mixed pregnancy results with multiple tests should see a doctor to determine if the pregnancy is progressing normally.
- The best time to take a pregnancy test is to wait until one or two weeks after a missed period, using the first urination in the morning.
- Although some home pregnancy tests are accurate in testing before a missed period, accuracy generally increases over time as hCG levels rise in early pregnancy.
- Testing too early may produce a false-negative result in pregnant women. Retesting one week after a missed period may indicate a positive result.
- Other factors such as irregular menstrual cycles, miscalculating ovulation date or misinterpreting test results may lead to inaccuracy of tests.
- Some conditions may warrant a blood pregnancy test, such as to confirm or rule out pregnancy complications.
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