What Affects Pregnancy Test Results: 9 Influencing Factors

| Reviewed By Amanda Lundberg, BSN, RN

Discovering that you are expecting a baby is a significant moment that can greatly impact your life. Therefore, it is crucial to ensure that nothing will provide a misleading sense of certainty, one way or another.

Does alcohol affect a pregnancy test? Alcohol will not affect a pregnancy test. The chemical reaction of the pregnancy test and the hCG from the urine cannot be influenced by alcohol. While alcohol does not impact test results, it can affect your pregnancy. Alcohol has been linked to severe birth defects and disabilities.

Understanding what factors influence a pregnancy test can help you achieve the most accurate result. Keep reading to learn more about what to avoid and what to embrace when taking a pregnancy test.

What Affects Pregnancy Tests

There are a plethora of situations in which a pregnancy test can yield a false result. Be it positive or negative, a false result can negatively impact your mental and physical health. Here’s what we know can influence pregnancy tests:

1. When Test Is Taken

Pregnancy tests detect a hormone called hCG that’s produced in the earliest stages of pregnancy. Most home pregnancy tests require at least 20 mIU/ml of hCG to provide a positive result.

It takes your body 10-14 days to build a detectable amount of hCG in the urine. This means that taking a pregnancy test too early can make the result inaccurate.

2. Time of Day Test Is Taken

Manufacturers, doctors, and mothers alike will tell you to take a pregnancy test in the morning.

This is because urine has the highest concentration of hCG in the morning following a long bout of sleep, during which you are not drinking any fluids or urinating.

Taking your pregnancy test at other times during the day can impact the result, especially early on.

3. Medications

Certain medications are thought, but not proven, to affect pregnancy tests. These medications include antihistamines, antidepressants, Parkinson’s medications, and antipsychotics.

Fertility drugs that contain synthetic forms of hCG are linked to false positive results. If you’re concerned about how your medications will impact a pregnancy test, it’s best to speak with your doctor.

4. Checking Results Too Soon or Too Late

Many pregnancy tests warn consumers not to read the result while processing. Reading too early usually results in the interpretation of a false negative.

Likewise, tests warn against reading results a certain amount of time past the processing window. Reading results too late can result in the interpretation of a false positive.

Evaporation lines occur when urine evaporates from the test leaving behind a faint and colorless line. These are one of the most common false positives and usually result from reading a pregnancy test past the designated time. 

5. Urine Too Diluted

Drinking excess water to ensure enough urine output is actually a harmful misconception. Drinking too much liquid can dilute the urine thereby diluting the hCG quantities within it. This can lead to a false negative pregnancy test result. 

6. High Levels of HCG

Too much hCG in the urine can actually have a counterintuitive effect and produce a false negative.

Pregnancy tests are designed to detect hCG in certain ranges. Going outside of that range to either extreme will invoke a negative result. While this is not common, it does happen.

7. Early Miscarriage 

A false positive is very rarely truly false. Rather, they often indicate the loss of a pregnancy or a nonviable pregnancy.

HCG can be detected in the urine for a few weeks following loss. When these levels are picked up, the test usually indicates a positive result. However, when a confirmation test or ultrasound is performed, no fetus is present.

8. Chemical or Ectopic Pregnancy

As mentioned previously, a false positive is rarely truly false. In the case of a chemical or ectopic pregnancy, the hCG levels are elevated enough to yield a positive result and an embryo is present but nonviable.

This means that the embryo will not develop normally and the pregnancy cannot continue. 

9. User Error

Following the instructions that come with the pregnancy test is vital. Messing up one part of the process can invalidate the result.

Many false pregnancy test results are due to user error. To avoid this, read through the instructions prior to beginning the test, and follow directions carefully. 

What Not To Do Before Taking Pregnancy Test

Here are a few things to avoid when taking a pregnancy test

  • Don’t take the test too early. Aim for the first day after your missed period or later. If you choose to take the test earlier, make sure to purchase an early detection test. 
  • Don’t drink too many fluids. You will have more than enough urine to take your test. Drinking too many fluids prior to a test can dilute the urine and affect the results. 
  • Don’t rush through your test. Take time to read the directions thoroughly.
A pregnant woman refusing an alcohol beverage being offered to her.

Drinking in Early Pregnancy Without Knowing

It’s advised that you stop drinking alcohol when you start trying to conceive. This prevents any accidents and safeguards your baby if you happen to get pregnant.

However, on occasion, women drink during the early weeks of pregnancy without knowing that they’re pregnant.

It’s thought that alcohol intake in the first weeks of pregnancy doesn’t affect the fetus as detrimentally as later in pregnancy.

This is because it takes almost a month for the placenta to develop, which is the main connection between mother and baby. 

As soon as you know you are pregnant or if you think you may be pregnant, you should refrain from drinking alcohol. 

Effects of Alcohol in Early Pregnancy

To be clear, there is no safe time to drink alcohol in pregnancy, nor is there a safe quantity or type of alcohol. It is recommended that alcohol be avoided altogether for the duration of your pregnancy.

The effects of alcohol use in any trimester can be detrimental to any part of the fetal anatomy and physiology, but even more so to specific developments taking place within each trimester. 

In the earliest part of pregnancy — weeks 1 to 3 — the placenta is still developing. So, the accidental intake of alcohol before knowing you’re pregnant isn’t as likely to hurt the baby.

However, in the weeks that come, your baby will rapidly begin the growth of several important organs and systems. 

Consuming alcohol during this time can lead to full or partial Fetal Alcohol Syndrome (FAS), Alcohol-Related Neurodevelopmental Disorder, and Alcohol-Related Birth Defects.

In the first trimester specifically, alcohol can negatively impact the development of the face and brain. 

Effects of Alcohol During Pregnancy: 2nd Trimester

Despite the organs and systems of the fetus being developed, alcohol in the second trimester can still damage them. 

In the second trimester, your baby is growing in size and weight. In addition, several important milestones are being met.

The baby’s eyes and ears are moving to the correct place on the head. The baby develops reflexes and responses to stimuli. The baby’s body begins to recognize sleep cycles, and the brain begins its most vital period of growth in the second trimester as well. 

Consuming alcohol during the second trimester threatens these important developments.

Children exposed consistently to alcohol in the womb during the second trimester tended to have alcohol-related birth defects in a physical capacity as well as displaying other cognitive and behavioral disorders.

Effects of Alcohol During Pregnancy: 3rd Trimester

In the third trimester, your baby grows rapidly as he or she prepares to be born. Alcohol consumption during this time can lead to serious issues such as premature birth and low birth weight.

This is in addition to all the other cognitive, behavioral, and physical manifestations of FAS that can occur. 

Related Questions:

Can I Have One Glass of Wine While Pregnant? 

Even though many expecting mothers partake in a glass of wine during pregnancy, the recommendation is still to avoid it altogether. Understand the risks of alcohol exposure in pregnancy before making any decisions regarding its consumption.

Can Alcohol Cause Miscarriage?

Studies have shown that women who drink more than four alcoholic beverages a week were at a higher risk for miscarriage than others. Additionally, women who drank spirits were also at a higher risk.


While alcohol consumption does not affect pregnancy tests, there are many factors that do. Understanding how each of these factors can impact a test will help you reduce the chance of a false result.

Though alcohol doesn’t make a difference in pregnancy tests, it can negatively impact your pregnancy. Refrain from alcohol during pregnancy to ensure the best outcome for your baby.