Pregnancy Tests


There are so many pregnancy tests on the market, some claim that you can "test five days before your missed period", there are even "digital" pregnancy tests that give you are "pregnant" or "not pregnant" readout.  Many women ask me how soon they can test and which test is the best. 

 

The chart below gives you an alphabetical list of some of the most common home pregnancy tests and the amount of hCG that has to be present to get a positive result.

Test

Sensitivity

Test

Sensitivity

Clearblue Easy +/-

25 mIU

Fact Plus

25 mIU

Clearblue Easy Digital

40 mIU

First Response Early Result

15-20 mIU

Early Pregnancy Test

20 mIU

hCG One Step Ultra

10 mIU

e.p.t. Certainty digital

50 mIU

New Choice (Dollar Tree)

20 mIU

Equate (Wal-Mart)

25 mIU

One Step Pregnancy Test

50 mIU

Normal hCG Levels               Could I be Pregnant?               Early Pregnancy Symptoms

Frequently Asked Questions About Pregnancy Tests             

Q: What is hCG?

A: hCG is human chorionic gonadotropin. It is a hormone produced by the placenta during pregnancy. Home pregnancy tests (HPTs) are designed to detect it.

Q: Why does the hCG level of the test matter?

A: Basically the pregnancy tests that detect the lowest number of units should be more sensitive and give you the earliest results. Although this isn't always the case.

Q: How do home pregnancy tests work?

A: Home pregnancy tests (HPTs) are designed to detect hCG, a hormone released by the placenta right after the embryo begins implanting into the uterine lining. The hormone is released in a pregnant woman's urine.

Q: How accurate are home pregnancy tests on the first day of a missed period?

A: The highest possible screening sensitivity for an hCG-based pregnancy test conducted on the first day of a missed period is 90 percent, as 10 percent of women may not have implanted yet.

Q: How soon after ovulation can I test?

A: The earliest you can get a positive result on the most sensitive pregnancy tests is seven days after ovulation. Implantation needs to occur before hCG is produced, and that generally happens between 6-12 days post ovulation, usually by 10 days after. For this reason, it makes sense to wait until 10-12 days after ovulation, but even then a significant percentage of women who are indeed pregnant will still show a negative result. If you have not had an hCG injection (common in fertility treatment, brands include Profasi, Pregnyl and Novarel), you can believe the positive, but you might get a false negative. If your period is late, test again. Your hCG levels should double every 2-3 days.

Q: How accurate are the home pregnancy tests that say you can get a positive result 3, 4 or 5 days earlier than other tests, or 3-4 days before you have missed a period?

A: Because implantation usually happens 6-12 days after ovulation, it is always possible that early testing will be too soon. Clearblue Easy publishes on its website the following stats: “Clearblue Easy can be used as early at 4 days before you expect your period. That's 5 days sooner than waiting until you miss your period to test. The amount of pregnancy hormone increases rapidly in early pregnancy. In clinical testing with early pregnancy samples, Clearblue Easy gave the following results. 53% of pregnant women get results 5 days sooner. 74% get results 4 days sooner. 84% get results 3 days sooner, 87% get results 2 days sooner.” With their digital test, they say 55% get a positive result 3 days before a woman’s period is due, 87% 2 days before, and 92% one day before. First Response and Answer say “Answer Quick & Simple® Early Result Pregnancy Test can detect the pregnancy hormone as early as 4 days before you expect your period. In clinical testing, Answer® detected the hormone levels in 69% of women 4 days before their expected period, in 83% of women 3 days before their expected period, in 93% of women 2 days before their expected period, and in 93% of women 1 day before their expected period.

Q: How do I perform the test?

A: You should use midstream urine -- meaning you should pee a little first and then either hold the test stick in your urine stream or use a collection cup. If you would like to collect urine in a cup even though you bought a stick test, you need to hold the absorbent tip of the stick in the cup of urine for 5-10 seconds

Q: How long do I need to hold my urine?

A: That depends how long after ovulation you are testing. If you are testing early, a four-hour wait is a good idea. The more hCG you have in your system, the less long you'll need to hold before trying to test.

Q: How do I read the test result?

A: You should check the instructions that came with the HPT as there are some differences between the tests. Most of the tests have two windows -- one that tells you the test has been performed correctly (control), and one that gives you the positive or negative result. In the result window, the tests usually give a line or a plus. For the line tests, any colored line, no matter how faint, in the result window during the allotted time is a positive result. Some of the tests give a plus or minus result. In those tests you expect one line, looking like a minus sign (-), in the result window for a negative, and two lines looking like a plus symbol (+) if you are pregnant. It is common for one line in the plus symbol to be lighter than the other -- any plus sign, no matter how varied the line colors, should be considered a positive result. All home pregnancy tests should be read within the time mentioned in the instructions and then thrown out to avoid confusion over evaporation lines.

Q: Can I use an HPT if I had an hCG injection (such as Profasi, Pregnyl or Novarel)?

A: You can, but you should wait 7-14 days after your last injection before the shot is out of your system. If you test too soon, you might get a false positive. Wait 14 days after a 10,000 IU injection, 10 days after a 5,000 IU injection, or 7 days after a 2,500 IU injection.

Q: Can fertility medications such as Clomid, Serophene, Gonal-F, Follistim, Humegon, Pergonal, Repronex or Fertinex cause false positive results on HPTs?

A: The only fertility medication that can cause a false positive on a home pregnancy test is one that includes hCG (see question above).

Q: Can progesterone supplements cause a false positive HPT?

A: No. Home pregnancy tests only check hCG levels, not progesterone. They are completely different hormones.

Q: If I take a pregnancy test and it looks positive at first but then the line disappears, am I pregnant?

A. Usually vanishing positives are actually a negative result and you are not pregnant. Some tests will tell you to confirm a negative result at 3 minutes or 5 minutes. Double checking results with another test is recommended.

Q: What if I took a test and it was negative, but when I looked at it an hour or more later I saw a faint line?

A: You may be pregnant and just didn't have a high enough level of hCG to trigger the test within the usual time frame; however, it also could be the way that test reacts over time, so you really need to test again either way in order to be sure of the result. Some brands indicate that an "evaporation line" will appear if the test is left to sit. Generally speaking, you should not rely on any positive result that does not show up within the time limit stated in the test instructions. All brands have the possibility of an evaporation line or chemical line.

Q: Are urine tests at the doctor's office any more sensitive than home tests?

A: They are usually equivalent to the first tier of the home pregnancy tests list above -- reading an hCG level of 15-25 mIU as positive. In fact, they are often the same tests listed in the chart, only with less packaging.

Q: How accurate are home pregnancy tests on the first day of a missed period?

A: The highest possible screening sensitivity for an hCG-based pregnancy test conducted on the first day of a missed period is 90 percent, as 10 percent of women may not have implanted yet.

Q: Can I tell if my hCG level is doubling by retesting with an HPT and looking for a darker line?

A: No. You may get a darker line as your pregnancy progresses, but the HPT is not accurate enough to give you a full picture. Only a quantitative beta hCG blood test can tell you this. Best to have the blood tests performed at the same lab since standards vary.

Q: What if my HCG levels aren't doubling every two to three days from a quantitative blood test?

A: It doesn't necessarily mean something is wrong, but it warrants further exploration including an early ultrasound (6 weeks LMP, 4 weeks after ovulation). Slow-rising hCG can be related to impending miscarriage or ectopic pregnancy. One important thing to remember is that on average hCG levels double approximately every two days from 4-6 weeks LMP, then doubles every 3 days when the level is 1600-6000, then the doubling slows to every 4 days or so. Levels peak a week or two before end of the first trimester (14 weeks LMP) before declining in the second trimester.

Q: I had a positive HPT, but my period started. What happened?

A: The only way to know for sure is to get a quantitative hCG blood test run. If you were pregnant but are miscarrying early, you may still have some level of hCG on the first day of bleeding -- but you need to go for the test as soon as possible. It is also possible that you got a false positive on the pregnancy test, in which case you should call the manufacturer with the lot number and try to get your money back.

Q: I have all the symptoms of pregnancy and got a faint positive on a home pregnancy tests. My qualitative (yes/no) hCG blood test came back negative. Am I pregnant or not?

A: It may be that the qualitative blood test is less sensitive than the home pregnancy test, so it would be a good idea to get a quantitative hCG (measures the actual hCG level). Also be sure you are reading the test within the time suggested in the instructions to ensure you are not seeing an evaporation line on your home test.

Q: Can you get a positive HPT with a lower level of hCG than the tests manufacturers say they detect?

A: Yes. Most of the tests can detect lower levels of hCG than what is listed in this FAQ, but the levels printed here are the ones quoted from the manufacturers.

Q: Can I be pregnant and not get a positive HPT?

A: Yes. Most women will register on HPTs by the time they are a few days late for a period, but not everyone will. If you suspect you are pregnant, you should see your doctor for a quantitative hCG test no matter what result you get from an HPT.

Q: If I have an ectopic pregnancy, will it register on a home pregnancy test?

A: In most cases an ectopic pregnancy will trigger a positive home test result. Ectopic pregnancies still produce hCG, though levels are often lower are double more slowly than in-utero pregnancies.

Q: My beta was 75 and I didn't get a positive on my HPT that is listed as reading a level of 50 or less, did I get a faulty test?

A: Not necessarily. The tests should read down to the level listed, but they don't always. It is possible the test was performed improperly, that urine was too diluted to give an accurate reading, or that test was not stored properly before use (tests that freeze, for example, are less likely to work).

Q: Can prescription or over the counter medication interfere with home pregnancy tests?

A: Medication will neither delay a positive result, nor cause a false positive, unless the medication contains hCG (Profasi, Pregnyl, Novarel). This includes pain relievers, antibiotics, etc.

Q: Do oral contraceptives/birth control pills interfere with home pregnancy test results?

A: No. One should get an accurate result on oral contraceptives. The hormones in the pill do not cause a false positive or a false negative result.

Q: Will recreational drugs or alcohol interfere with home pregnancy tests?

A: Drugs such as cocaine, marijuana, heroine, and alcoholic drinks will not alter the result of a home pregnancy test, but it is better to test when not under the influence.

Q: Can a urinary tract infection cause a false positive home pregnancy test?

A: No. Home pregnancy tests detect the hormone hCG, not byproducts of infection. Infections do not cause the hormones to be released. It is best to get the pregnancy confirmed by a doctor and have the UTI treated as soon as possible.

Q: Can stress cause a false positive result?

A: No.

Q: How soon after a miscarriage will an HPT be reliable?

A: It varies. Sometimes it takes awhile for hCG levels to go back to zero, so it is possible to get a positive HPT from a miscarriage for a month or more after a loss. If hCG levels were followed back to zero, then a positive HPT should indicate a new pregnancy.

Q: What is the normal level of hcg in a women who is not pregnant?

A: A normal non-pregnant hCG level is under 2; however, labs have different standards as to what they consider positive. Some lab norms say a level is negative under 5, under 10, or under 25.

Q: If your period stopped because of menopause will it give a false positive reading on test?

A: No. The hormone hCG is produced in pregnancy. While other hormones fluctuate as women approach menopause, hCG is not one of them.