Can you do a pregnancy test while on your period

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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If you’re trying to get pregnant, the best time to take a pregnancy test is one week after you’ve missed your period. Why? Because this is really the best way to prevent a false negative result (a negative test in someone who's actually pregnant) result.

Home pregnancy tests can be used as early as the first day after your first missed period in women with regular/predictable monthly menses. If you have irregular periods, you can administer a test 14 days after intercourse, since you likely can’t pinpoint your exact time of ovulation.

Pregnancy tests detect a hormone called human chorionic gonadotropin (HCG), which is produced in early pregnancy. The production of this hormone begins slowly and increases as the pregnancy grows. Standard urine pregnancy tests will detect the HCG level when it reaches 20-50 milliunits/milliliters.

If you take a test too soon (before you've missed your period), the levels of HCG may not be high enough to detect a pregnancy and it could cause a negative result, even though you're actually pregnant.

I advise my patients to wait at least one day after you miss your period. If you wait one week after a missed period, the chance of a false negative is very low if you have a normal monthly menstrual cycle.

Brand name versus generic pregnancy tests

Home pregnancy tests, both brand name and generic, are very accurate at detecting the HCG hormone and any positive result, even a faint line, can be considered positive. HCG is only produced by a pregnancy; any positive result indicates a pregnancy.

You don’t need a serum (blood) pregnancy test to confirm pregnancy. Both urine and blood detect HCG, although the blood test is more sensitive and can detect HCG levels at much lower levels than a urine test. In certain situations, your doctor may want to perform a blood HCG test but it’s not typically needed to confirm a pregnancy.

Although most tests advertise 99% accuracy, the ability of a particular brand to detect HCG at levels less than 50 ml may vary. Some brands may be better able to detect lower levels of HCG than others. If your HCG level is more than 50 ml, which is the detection rate of most tests, even generic tests will detect a pregnancy accurately.

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