Everything You Need To Know About Home Pregnancy Tests

Everything You Need To Know About Home Pregnancy Tests

laflor via Getty
laflor via Getty

Taking a pregnancy test can be the most nerve-wracking two to five minutes of your life. Yet surprisingly, very few women seem to know how they work. Well, today I’m going to give you some awesome background knowledge on pregnancy tests.

Pregnancy tests have been around forever. 

Believe it or not, the earliest forms of the pregnancy test were on the scene around 1350 BCE. Ancient Egyptians peed on wheat and barley to confirm whether or not a woman was with child — it could even predict gender. What’s even wilder is they tested this method in the early ’60s and it predicted with 70% accuracy. Not bad for a pre-Google society!

How do they work?

Modern day home tests work by detecting The Pregnancy Hormone or human chorionic gonadotropin (HCG) in urine. Typically, the hormone becomes present shortly after a fertilized egg buries into the uterine lining. HCG levels multiple every few days from there on.

What is the best time to take them?

The best time to take a urine pregnancy test is the day after your missed period. Assuming a woman has a consistent follicular phase (the time your body produces hormones that allow your eggs to mature) and luteal phase (the time from ovulation to your next period), your body will have had enough time for the egg to implant and start producing HCG by that time. Having regular menstrual cycles makes it easier to know when to test. And having irregular cycles could make timing the pregnancy test more challenging.

Why do they fail sometimes?

Unfortunately, very few women have the idealized “regular 28-day cycle” and they can vary widely from 21 to 35 days. And some conditions, like polycystic ovarian syndrome (PCOS) or luteal phase defects, can require medical intervention to help regulate cycles. Because of this, the best time to take a pregnancy test really depends on your knowledge of your cycle. The goal is several days after you believe you have implanted or around 14 days after you have ovulated.

Are some brands really better than others?

With correct use, all pregnancy test should be able to determine if one is pregnant. Most of them claim to be about 99% accurate, but if you keep reading that only applies after a missed period. The biggest difference is how long the test will take to detect pregnancy based on the presence of HCG in urine. However, from time to time women get false negatives or false positives.

Do cheaper brands work as well as more expensive brands?

In general, yes. Cheaper test and digitals often require higher HCG levels for detection, but don’t count a test out because of its price. Many TTC’ers swear by the dollar store $1 test.

What causes a false negative? 

False negatives occur for many reasons. The most common is taking a pregnancy test too early. As someone who has been through two rounds of TTC, I have learned the hard way that every day counts for detectable HCG levels. Other reasons for false negatives include: low test sensitivity, user error, expired test, or diluted urine. Also, no one knows why, but there are some women who just don’t get positives on a urine test and have to confirm via blood test.

False negatives are much more common than false positives.

What about false positives?

False positives are a bit more complex. Ectopic pregnancy, a recent miscarriage/ chemical pregnancy, and fertility medicine can all lead to false positives. Similarly, user error or evap lines can lead to false positives.

A false positive can also be a sign of something more serious. In my case, a false positive shortly after delivery was one of several signs that I was experiencing a retained placenta after giving birth. Other medical conditions like kidney disease, ovarian cyst, and ovarian cancer can also lead to incorrect results.

Always follow the instructions.

Different tests have different methods. If the test says to use the dropper, you can’t pee on the test. If it says five days after your missed period, taking it three days after ovulation probably won’t be too helpful.

Pay attention to those expiration dates.

Each pregnancy test comes with an expiration date. It’s important that you don’t use a test past that date for risk of an unreliable result.

We’ve come a long way from the pee on crops days. But I’m sure the women were equally as anxious to see the results as we are today.