How long before period can you take a pregnancy test

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.

Table of Contents Show

Brand name versus generic pregnancy tests
How to prevent a false negative result
Medications and test results
When to see your doctor
1. Missed period
2. Breast changes
3. Light bleeding
5. Nausea and vomiting
7. Headache
8. Food aversions or cravings
9. Changes in bathroom habits
10. Feeling “different” and mood changes
11. Missed birth control
Can I take a pregnancy test 7 days before my period?
Can I take a pregnancy test 1 week before my period?
Can I take a pregnancy test 8 days before my period?

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.

How to prevent a false negative result

The number one cause of a false negative test is taking the test too soon after you conceive. Also, if you don’t follow the test instructions carefully, it could affect your result.

Urine, even in women who drink large amounts of water, should still yield a positive result. But urine shouldn’t be diluted with water before taking a test. A good time to take the test is in the morning when you first wake up.

If a test is negative in a woman who suspects she’s pregnant or if she has irregular cycles, she should repeat the test in one week.

Medications and test results

Medications don’t typically interfere with results, neither causing false positive nor false negative. Only a medication containing HCG would affect the result.

When to see your doctor

Although home tests can detect a pregnancy, it gives no information as to viability. It’s important to make an appointment with your doctor to confirm your pregnancy and to detect a fetal heart rate through an ultrasound (usually at six to 10 weeks). If you have a positive pregnancy test, your obstetrician can provide information about warning signs of an abnormal or worrisome pregnancy and can advise you on when to make an appointment to confirm your pregnancy.

Many early signs of pregnancy can be nonspecific and easily mistaken for other causes. For this reason, it may be difficult to know when or whether to take a pregnancy test.

In this article, we list 11 early signs that can indicate a person should take a pregnancy test.

A pregnancy test will not show positive as soon as a person becomes pregnant. It takes time for the body to release enough of the hormone human chorionic gonadotropin (hCG) to show up on a test. This will be around 12–15 days after ovulation if a person has a 28-day cycle.

Some medical bodies suggest taking the test on the first day a period should have occurred. However, the Food and Drug Administration (FDA) notes that the results on this day may not be accurate for 10–20% of people. Instead, they suggest taking a test 1–2 weeks after missing a period. Some tests are more sensitive, however, and a person can use them earlier.

Another option is to wait at least 21 days after having sex without birth control.

Blood tests take place in a medical office, and they can show if a person is pregnant around 6–8 days after ovulation.

What are homemade pregnancy tests, and do they work?

If a person is pregnant, it is best to find out as soon as possible. Not only can they start planning the next steps, but there may also be health considerations and lifestyle changes to address.

Some people notice early signs of pregnancy, such as fatigue or breast tenderness, before they miss a period.

The early signs include:

a missed period
breast changes
light bleeding
cramps
nausea and vomiting
fatigue
headache
food aversions or cravings
changes in bathroom habits
mood changes
missed birth control

1. Missed period

Often, the earliest and most reliable sign of pregnancy is a missed period.

There are many reasons for missed periods, but if a person is sexually active, a missed period can signal pregnancy.

Most pregnancy tests are very accurate when taken after a missed period, but sometimes the hormone levels might not be high enough to trigger a positive result.

If someone misses a period and a pregnancy test is negative, they should repeat the test after a few days.

2. Breast changes

Breast changes are common in early pregnancy. These are due to hormonal changes that eventually prepare the body for lactation.

Common changes are:

breast tenderness
swollen breasts
the nipples and areolas becoming larger or slightly darker

Which breast changes are a sign of pregnancy?

3. Light bleeding

Around 25% of people experience implantation bleeding, which is light bleeding that happens when the embryo attaches to the uterine wall.

Implantation bleeding tends to be lighter and shorter than a menstrual period.

Implantation bleeding happens around 6–12 days after conception, but light spotting is not uncommon during the first 12 weeks of pregnancy.

4. Cramps

Cramps are common before or during a menstrual period, but some people also get cramps when implantation occurs.

If cramps occur around or before a period is due, but there is no bleeding, or the bleeding is much lighter than usual, it may be a good idea to take a pregnancy test.

How do I know if cramps are a sign of a period or pregnancy?

5. Nausea and vomiting

Morning sickness, or nausea and vomiting associated with pregnancy, may start 2–8 weeks after conception.

Nausea does not just happen in the morning. It may occur at any time during the day or night.

If nausea happens for no apparent reason, especially with other possible signs of pregnancy, it may be a good idea to take a pregnancy test.

6. Fatigue

Fatigue is a common symptom of early pregnancy, and a person may feel the need to rest or nap for no apparent reason.

It is typically due to changes in the hormone progesterone.

Fatigue typically eases in the second trimester, and the person may find they have more energy again.

7. Headache

Hormonal changes may also trigger headaches in early pregnancy. They typically ease over time.

A person can take paracetamol for a short time to treat a headache, but it is best to check with a doctor or midwife first. Other pain relief drugs may not be safe to take.

From week 20 of pregnancy and after, headaches can be a sign of preeclampsia, a potentially life threatening condition that needs urgent medical attention.

What does headache mean in pregnancy, and how can I manage it?

8. Food aversions or cravings

Unusual cravings and food aversions are common in the first trimester, though they sometimes persist through the entire pregnancy.

Some people crave nonfood items, such as dirt or ice. This is known as pica. Anyone who craves things that are not food should consult a healthcare professional.

A person may also find they no longer enjoy foods they previously enjoyed or that their taste and smell become more sensitive.

Do food cravings only happen during pregnancy?

9. Changes in bathroom habits

Bowel and bladder symptoms can appear in early pregnancy. A person might experience frequent urges to urinate during the day and night. They may also have constipation, which affects 11–38% of people at some time during pregnancy, according to 2012 research.

In the early stages of pregnancy, the rise in hCG levels boosts blood flow to the pelvic area, increasing the need to urinate.

Learn more about frequent urination in pregnancy.

10. Feeling “different” and mood changes

Anecdotal evidence suggests many pregnant people report feeling “different” early in pregnancy, with some feeling an awareness that they are pregnant before taking a test. However, there is no scientific evidence to confirm this.

Physiological and hormonal changes during pregnancy may cause a person to feel different. Feeling different may also be due to mood changes, which can begin within a few weeks after conception.

Anyone who believes that they may be pregnant should take a test for confirmation.

Is it premenstrual syndrome or pregnancy?

11. Missed birth control

A person should consider taking a pregnancy test if they are sexually active and have not used birth control within the last month.

Many birth control options effectively prevent pregnancy, but a broken condom or missed birth control pill can increase the chance of conception.

Pregnancy tests work by detecting the hormone hCG, which the body starts producing after conception. According to 2014 research, hCG is detectable in the blood around 8 days after conception. As the pregnancy progresses, levels rise by around 50% a day. HGC is detectable in urine a few days later than in the blood.

Tests for home use are urine tests. A person will need to go to a healthcare facility for a blood test.

A range of pregnancy tests are available for home use, and some are more sensitive than others. This means they can detect hCG at lower levels.

Many tests claim to be 99% accurate, but experts note that not all of them undergo rigorous scientific testing. A person may also get a false-negative result if they take the test too early, do not follow the instructions precisely, or do not handle the test as the manufacturer intended.

Some medical bodies suggest taking a test on the first day of a missed period, but many people do not know when their period should arrive, for example, if they experience irregular menstruation.

When taking a test, a person should:

read the instructions carefully
ensure they handle the test as advised
try to avoid taking the test too early

The FDA notes that a positive test is usually but not always accurate. If a test is negative, they suggest avoiding alcohol and other substances that may be harmful to a fetus and repeating the test at a later date or seeking medical advice.

Why might a person get a false-positive pregnancy test result?

Some people experience menstrual irregularities, breast changes, and other pregnancy-type symptoms without being pregnant. These can happen for a variety of reasons.

Possible biological factors include hormonal changes due to another health condition. Psychological and social factors can sometimes play a role.

In rare cases, a person can have pseudocyesis, sometimes called false pregnancy, where they firmly believe themselves to be pregnant and have signs of pregnancy without being pregnant. This condition is not well understood and can happen for various reasons.

Anyone who has signs of pregnancy but is unlikely to be pregnant, for example, because of menopause, should seek medical advice. They may have a health condition that needs medical treatment.

If a pregnancy test result is positive, a person should contact a midwife or doctor. They can confirm the result with a blood test or schedule an early ultrasound.

If the person is pregnant, they should start prenatal care or discuss other options as early as possible.

If a person misses a period but is not pregnant, a healthcare professional can help diagnose any underlying cause.

The earliest sign of pregnancy is often a missed period, but breast changes, fatigue, headaches, and other changes can also appear within the first few weeks.

Anyone who has had sex without birth control and experiences early signs of pregnancy should do a test.

Anyone who has signs of pregnancy but is sure they cannot be pregnant should seek medical advice. The healthcare professional may wish to rule out other health conditions or provide treatment if required.

Can I take a pregnancy test 7 days before my period?

Clearblue Early Detection Pregnancy Test can tell you 6 days sooner than your missed period (which is 5 days before your expected period)¹. No matter when you test, you can be confident in the accuracy of a 'Pregnant' result with any Clearblue Pregnancy Test.

Can I take a pregnancy test 1 week before my period?

Early Detection The most sensitive tests on the market can potentially give you a positive result four to five days before your period is due, meaning you don't necessarily have to wait for a missed period, or watch for other pregnancy symptoms, to find out whether you are pregnant.

Can I take a pregnancy test 8 days before my period?

Trace levels of hCG can be detected as early as eight days after ovulation. That means you could get positive results several days before you expect your period to start.