Negative pregnancy test a week after missed period

It may be that you have taken a pregnancy test because you are actively trying to get pregnant. Or, perhaps quite the opposite, and you are concerned you are pregnant but not trying to conceive.  Whatever the reason, false-negative or false-positive results can happen. Let's look at pregnancy tests in a little more detail and why a false result may occur.

How do Pregnancy Tests Work?

Your body produces a hormone called Human chorionic gonadotropin (hCG) when you get pregnant. When a fertilized egg attaches to the lining of your uterus (right at the beginning of pregnancy), your body begins to release HCG. It starts to produce hCG around six days after fertilization. 

Pregnancy tests detect hCG levels in the urine. hCG levels rise quickly, doubling every two to three days. Most pregnancy tests advise that they are accurate when taken from the first day of a missed period. But, if you don't know when your next period is due or you have irregular periods, you can do the test at least 21 days after you last had unprotected sex. 

Some pregnancy tests are more sensitive and claim you can use them before a missed period. However, they are not likely to be as accurate when taken early.

How accurate are home pregnancy tests?

Home pregnancy tests are usually very accurate. When taken on the first day of a missed period, some home pregnancy tests claim to be 99% accurate. This accuracy reduces the earlier you take the test before your missed period. 

Home pregnancy test accuracy can depend on:

• When you take the test
• The time of day you take the test
• How you take the test
• The brand of the test

If you think you have a false test result, the best option is to wait a few days and then try again. 

What are false pregnancy tests, and how do they happen?

Even though home pregnancy tests are very accurate, they can provide false results very occasionally. 

• A false positive is a test result that shows you are pregnant when you are not.
• A false negative is a test result that shows you are not pregnant when you are. 

Reasons your test might be wrong

False-positive results can occur due to:

• Reading the test after the recommended time frame. Some tests develop evaporation lines after a certain amount of time, making the pregnancy test look positive. Therefore, it's important to read the test within the described time frame. 
• A molar pregnancy (which is a condition where a tumor grows in the uterus mimicking pregnancy).
• Medications that contain synthetic hCG, such as some fertility medications.
• Medical conditions such as ovarian cysts, some cancers, kidney disease, or disorders that affect the pituitary gland and hormones. 
• A recent miscarriage, incomplete miscarriage, or abortion where your hCG levels have not yet returned to normal. 

False-negative results can occur if:

• You take a pregnancy test too early, before your missed period, so there is not enough hCG in your urine to detect.
• You check test results too soon, and it hasn't had time to process correctly. It's essential to follow the instructions on the pregnancy test packet or leaflet to have the best chance of getting an accurate result. 
• You take the test late in the day, and your urine is more diluted. Although pregnancy tests can work at any time of day, you are more likely to get a more accurate result if you take a pregnancy test first thing in the morning. This is because hCG levels are more concentrated in the urine at this time.

Colorado Obstetrics & Women's Health

If you are concerned that your pregnancy test result is false, you can see an obstetrician for a blood test. At Colorado Obstetrics & Women's Health, our team of expert clinicians is here to support you through every stage of pregnancy. Right from before conception. Contact us today at (719) 634-8800 to schedule your appointment. 

If you’ve ever experienced a missed period but had a negative pregnancy test, you may be wondering if you can actually trust the results of the test.

Although it is possible to be pregnant and still have a negative pregnancy test, there are also some other reasons why you might get a negative result with a missed period. 

There are six primary causes of a missed period but a negative pregnancy test, including low hormone levels, lifestyle factors, ectopic pregnancy, breastfeeding, medication use, and certain medical conditions.

Low Hormone Levels

Pregnancy tests work by detecting the presence of enough hCG hormone (or human chorionic gonadotropin) in the urine or blood.

This hormone is sometimes referred to as the pregnancy hormone because it is produced in excess during pregnancy. 

An elevation in the amount of hCG starts at conception and typically peaks at about 8 to 12 weeks into a pregnancy.

Rising levels of hCG are one of the early signs of pregnancy, detected both by a urine test and a blood test.

The date of conception can vary widely between individuals depending on their unique ovulation cycle.

A study conducted in 2014 found that at-home pregnancy tests need to detect hCG levels above 25 milli-international units per milliliter (mIU/mL) in order to detect pregnancy in 99 out of 100 cases. 

However, depending on when a woman conceives, her hCG levels may not be high enough shortly after a missed period to be detected by the pregnancy test.

Women who conceive later in their cycle will still miss a period but may still get a negative test result because there simply hasn’t been enough time for hCG to accumulate.

This is called a false-negative result because although the woman is pregnant, the test is falsely showing a negative result that indicates she is not pregnant (as opposed to the much less common false positive, where the test indicates a pregnancy when the woman is not actually pregnant). 

If you think you might be pregnant but get a negative test result, wait a few days before taking another urine pregnancy test.

Remember that a faint line still counts as a positive pregnancy test. Pregnancy tests offer the most accurate results when taken at least one week after a missed period. 

Lifestyle Factors

A missed period can also occur as a result of other factors, including specific elements of a person’s lifestyle. 

One of the lifestyle factors most commonly attributed to a missed period is stress.

Experiencing a large amount of physical or psychological stress can delay a woman’s period even though she is not pregnant.

Consistently excessive exercise can even lead to a reduction in body fat so significant that it can cause a woman to stop menstruating, resulting in a period occurring well past the expected period date.

A poor diet, specifically failure to take in enough essential nutrients or enough calories, can also cause a woman to miss her period.

On the note of dietary habits, higher-than-average daily caffeine intake is an often-unexpected cause of an irregular period. 

Ectopic Pregnancy

An ectopic pregnancy is a pregnancy that occurs when an egg is fertilized by a sperm but implants outside of the woman’s uterus, most commonly in the fallopian tube.

Ectopic pregnancies are not viable and can potentially be life-threatening to the mother if not treated. 

Because the egg has been fertilized, the body begins preparing for pregnancy, resulting in a missed period. However, levels of hCG in the urine or blood may not be detectable, thus resulting in a negative pregnancy test. 

Studies show that up to 3 percent of ectopic pregnancies may result in a negative test.

While rare, it is possible to have a negative pregnancy test and still experience an ectopic pregnancy. 

If you have a missed period and experience any of the following symptoms with a negative pregnancy test, seek medical attention:

• Nausea or vomiting
• Dizziness or lightheadedness
• Severe pain in the lower abdomen or one side of the abdomen
• Bleeding or spotting

Breastfeeding

If you’ve ever heard the old adage that it’s not possible to get pregnant while breastfeeding, you’re not alone.

While it is true that breastfeeding can cause irregularities in a woman’s menstrual cycle, including late periods or missed periods, it is still possible to get pregnant while breastfeeding. However, the chances are less likely. 

As your baby grows, his or her feeding needs change from month to month, which can place increased stress on your body.

These changes can make your cycle irregular from month to month, resulting in a missed period with a negative pregnancy test.

Medication Use

The use of certain medications can also contribute to a missed period with a negative pregnancy test.

The medications most commonly associated with a missed period are birth control pills or other forms of hormonal contraceptives. These medications help to prevent pregnancy by thinning the lining of the uterus, which is shed during menstruation. 

Women who have taken hormonal contraceptives for an extended period of time or who take high doses of hormones can stop having periods completely.

Approximately 15.4 percent of women with a hormonal IUD were found to completely stop having periods, in one study.

Other medications that can contribute to a missed period include certain types of blood pressure drugs or allergy medications. 

If you miss your period but experience a negative pregnancy test and you’ve recently started or changed medication, check with your doctor or pharmacist to see if one of the drugs you are taking could be the cause.

Medical Conditions

Certain medical conditions can contribute to an irregular menstrual cycle or even missing periods altogether. 

Women suffering from polycystic ovary syndrome (PCOS) can experience significantly irregular cycles, causing missed periods (or more accurately, skipped periods).

Women with thyroid or other hormonal disorders can also experience missed periods. 

Women with eating disorders may also miss periods if they lose too much body fat. The condition, called amenorrhea, is commonly found in women suffering from severe anorexia or exercise bulimia. 

The Bottom Line

There are six primary causes of missing a period but receiving a negative pregnancy test result, including low hormone levels, lifestyle factors, ectopic pregnancy, breastfeeding, medication use, and certain medical conditions. 

If you think you might actually be pregnant, try waiting two or three days before retesting to see if you get a positive result.

Always seek medical attention from a healthcare provider if you have a missed period and negative test but are experiencing early pregnancy symptoms or those of a possible ectopic pregnancy.

References and Sources:

A unique case of ruptured ectopic pregnancy in a patient with negative preg-nancy test - a case report and brief review of the literature | National Library of Medicine 

Association of Baseline Bleeding Pattern on Amenorrhea with Levonorgestrel Intrauterine System Use | National Library of Medicine 

Association between menstrual disturbances and habitual use of caffeine | ScienceDirect. 

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