- There are two main types of pregnancy tests: urine and blood tests.
- Take a home urine test after your next missed period — anywhere from 14 to 18 days after conception.
- Blood tests are more sensitive and can tell you if you're pregnant 6 to 14 days after conception.
You have two options when it comes time to see if you have a baby on board.
The most common is an at-home urine pregnancy test, available over the counter, though you can take a urine pregnancy test at a medical clinic. Another option is a blood test performed at a medical clinic.
"Both tests check for a hormone called human chorionic gonadotropin, or hCG," says Crystal Newby, MD, of Kansas City Ob-Gyn. "This hormone is produced after a fertilized egg attaches to the wall of your uterus."
The egg typically attaches 6 days after fertilization, at which point, hCG levels in your blood and urine will increase for the next 6 to 10 weeks. Once hCG levels are high enough, you can expect an accurate reading, but not before then.
When should you take a blood pregnancy test?
Depending on a woman's cycle, a blood test can detect pregnancy between 6 and 14 days after conception.
Blood tests for pregnancy are more sensitive to hCG than home pregnancy tests. They can detect this hormone in low quantities and tell you if you're pregnant sooner than a home test.
While blood tests can provide results sooner than home pregnancy tests, they are usually more expensive and take longer to provide results because the blood must be sent to a lab for analysis.
If the lab is in-house then it will take a few hours. But if the lab is at a different location, it could take several days to learn the results.
When should you take a home pregnancy test?
Most home pregnancy tests advise you to take the test after you miss your next period. If you have a standard 28-day cycle, you'll be most fertile two to three weeks before your period.
So if you get pregnant during that fertility window, you'll need to wait at least 14 to 18 days after conception to take a home pregnancy test.
If you get a negative result and suspect you're pregnant, check the instructions on the box. Home pregnancy tests typically recommend retaking the test 5 to 7 days later, when the hCG levels in your body will be higher.
This type of result is called a "false negative." Sometimes you can receive a false negative result if you take a pregnancy test too soon when your hCG levels are too low for the test to detect them accurately.
Moreover, recent miscarriages, fertility drugs, and rare hCG secreting tumors can interfere with the results of at-home urine tests. If you receive conflicting results after taking a home pregnancy test multiple times, doctors recommend a blood test.
How accurate are pregnancy tests?
Blood pregnancy tests are considered by doctors to be 99% accurate. Quantitative blood tests (also called beta hCG tests) are the most accurate blood tests and can help doctors tell the exact age of the fetus and play a role in detecting any abnormalities.
If you follow directions, home pregnancy tests are an estimated 97% to 99% accurate. If you perform a urine pregnancy test in a lab setting, like at your doctor's office, the accuracy will be closer to 99%. It's important to make sure that you check the expiration date on your home test, as it can affect the accuracy of the results.
After taking either a blood or urine test, it's important to confirm the pregnancy with an early ultrasound.
Insider's takeaway
Home pregnancy tests can provide results faster and be more convenient than a blood test. But you'll probably have to wait longer to receive accurate results.
You can expect accurate results from a blood pregnancy test as soon as 6 to 14 days after conception. Because the test must be analyzed in a lab, it could take up to several days to get the results.
To get the most accurate reading from a home urine test, wait until your missed period. This can come anywhere between 14 to 18 days after conception. If you get a negative result, you can try taking a home test again in 5 to 7 days to see if you have higher amounts of detectable hCG in your body.
Blood tests are considered to be 99% accurate, while home pregnancy tests are around 97% to 99% accurate. Regardless, you should confirm your results by getting an ultrasound.
Denice Rackley is a freelance writer for Insider.
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You may suspect that you are pregnant when you have unusual symptoms of pregnancy or if you have missed your period. If you have regular periods and have missed your period by a week, it is likely that you are pregnant. However, if you have irregular menstrual cycles, look out for other symptoms of pregnancy.
For a start, confirm your suspicion by buying an over-the-counter urine pregnancy test kit. There are many brands of pregnancy test kits available in the market, which are quite reliable. These are available at our local pharmacies. Alternatively, you could go to your doctor for a test.
What is a Pregnancy Test Kit?
During
pregnancy, a hormone called human chorionic gonadotrophin (hCG) is produced, which circulates in the blood and is also present in the urine.
The pregnancy test kit detects the presence of hCG in your urine. It is a qualitative test. Some pregnancy test kits are more sensitive than the others but most will be able to detect hCG between the fourth to fifth week of your pregnancy. This means that for those with regular cycles, the test should be positive once you have missed your period by a few days.
Although almost all over-the counter pregnancy test kits detect pregnancy by measuring hCG in the urine, you have to read the instructions for the test kit because instructions for usage are different for different test kits.
An indicator will show if you are pregnant. For example, some kits will show two bold lines if positive (Figure 6.2) and one bold line if negative (Figure 6.3). These indicators are different for various
kits.
How Accurate are the Pregnancy Test Kits?
Pregnancy tests are rarely wrong. It is more than 99% accurate. Thus, if your test is negative, it means that you are not pregnant; However, if you are very early in your pregnancy and the test is done too early, there could be insufficient amount of hCG in the urine for the test to detect.
So, if a test comes back negative but you strongly suspect that you are pregnant, repeat the test in a few days’ time.
There are rare examples when the hCG level is raised transiently and then drops to zero. This is known as “biochemical pregnancy” and could be the cause of a false positive result of the test kit. This initial rise of hCG levels would soon drop in “biochemical pregnancy” and result in a negative test result. Vaginal bleeding occurs soon after, which would coincide with “delayed menses”. Also rarely, there could be occasional ovarian tumors which secrete hCG and the false positive result could be wrongly interpreted as a pregnancy.
Frequently Asked Questions
1. Do I have to test with first morning urine?
Although you can test any time of the day, your first morning urine specimen is usually the most concentrated of the day and would have the most pregnancy hormones in it.
2. When should I take the test if I suspect that I am pregnant?
You can test your urine as early as six days past ovulation but the first day of your missed period is recommended for greatest accuracy.
3. Do I need a blood test for hCG to confirm my pregnancy?
Blood tests for hCG are more accurate in detecting HCG and they can also measure the actual levels of the hormone. These tests may be useful to
differentiate a miscarriage when the blood hCG will drop with time or a healthy pregnancy when the blood hCG level will double every two days. Occasionally, we need to follow-up the hCG levels to help us diagnose an early ectopic pregnancy (pregnancy that is outside the womb), which could be potentially life-threatening or confirm a miscarriage.
Acknowledgement
Source: Dr TAN Thiam Chye, Dr TAN Kim Teng, Dr TAN Heng
Hao, Dr
TEE Chee Seng John, The New Art and Science of Pregnancy and Childbirth, World Scientific 2008.
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