When you get a positive pregnancy test result when you’re not expecting one, it can come as a huge shock. In this situation it’s natural to wish that the results aren’t real. Many women who come to our center ask us if it’s possible they got a “false positive” on their home pregnancy test or the free test from our clinic. But this often isn’t the case.
How Pregnancy Tests Work
Before talking about how a false positive can happen, it’s important to understand how a pregnancy test actually works.
When you become pregnant, your body starts going through a huge number of rapid changes to prepare for the pregnancy. Most of these changes are triggered by hormones that affect different parts of your body. Hormonal changes are also the reason many women experience side effects during early pregnancy such as nausea, lightheadedness, cramping, and body aches.
A pregnancy test works by detecting these hormone levels in your urine - specifically, the hormone hCG, or human chorionic gonadotropin. This hormone is only produced by your body when you are pregnant, from cells produced in the placenta. When a pregnancy test detects its presence in your urine, it almost always means you are pregnant.
However, it takes time for hCG levels to build up in your body. hCG levels roughly double in your bloodstream every three days, but they are too low to detect until about 12 days after conception. If you take a pregnancy test before this, you could still get a negative result, even if you are actually pregnant. These “false negatives” are very common in early pregnancy.
The Trouble with False Positives
While false negatives are very common, a false positive - where a pregnancy test tells you you’re pregnant when you aren’t - is extremely rare. That’s because there are very few circumstances when your body would produce hCG without being pregnant.
The most common cause of false positives is when you experience a “chemical pregnancy.” This term is slightly misleading, as a chemical pregnancy is actually a pregnancy, but it ends in very early miscarriage. Most chemical pregnancies spontaneously miscarry by about the fifth week. This is late enough that pregnancy tests can detect hCG in your body but too early for an ultrasound or other procedure.
You can also get a positive pregnancy test result from an ectopic pregnancy, which is a pregnancy that implants outside the uterus. Ectopic pregnancies are relatively rare, but they are also extremely dangerous for the mother. If an ectopic pregnancy isn’t caught early, it could cause your fallopian tubes to rupture, causing massive internal injuries. A doctor or clinic can diagnose an ectopic pregnancy through an ultrasound examination.
Medical Conditions & Medications
There are also some medical conditions that can cause false pregnancy positives. These conditions can vary, but some of the more common ones include urinary tract infections, ovarian cysts, and kidney diseases. Additionally, you can get a false pregnancy positive after taking certain medications, including anxiety medications like Xanax or Valium, medications containing promethazine, and certain antipsychotic and anticonvulsant medications.
Mistakes When Taking the Test
Finally, the most common cause of a false positive is simply not following instructions when taking a pregnancy test. You should always check to make sure the pregnancy test you are using isn’t expired, and you should carefully time how long the test is in your urine stream to get an accurate result.
How to Get an Accurate Pregnancy Test
The best way to make sure you get an accurate pregnancy diagnosis is to visit a doctor, clinic, or pregnancy center. These places all have trained and helpful staff who can ensure you take the test correctly and get an accurate result. If you do get a positive test, you can also follow up with an ultrasound to ensure your pregnancy is healthy and viable.
At Ava Women’s Center, we offer free pregnancy testing and free ultrasound examinations to make your pregnancy results simple, safe, and convenient. Call us today at 844-371-4282 to schedule an appointment at our center or to ask questions.