Pregnancy Test Sensitivity and Early-Detection Testing

Pregnancy Test Sensitivity and Early-Detection Testing

Early Pregnancy Tests: How Soon Can I Test for Pregnancy?

HCG pregnancy tests determine pregnancy through the detection of the hormone hCG (Human Chorionic Gonadotropin) in a woman's urine. In technical terms, hCG is a glycoprotein hormone secreted by the developing placenta shortly after a fertilized egg has implanted in the uterine lining.

Clinically speaking, HCG is measured in thousandths of International Units, or mIU. Pregnancy tests with a sensitivity of 20 mIU/ml are more sensitive than tests with 50 to 100 mIU/ml. Test brands will display how sensitive their tests are using mIU as the standard unit of measure. Test sensitivity equates with early-detection - and the lower the number, the sooner a test can detect pregnancy. The most sensitive pregnancy tests can detect hCG levels at as low as 20 mIU - or at around 8 days following implantation of the egg. is one of the first Internet providers of FDA approved early home pregnancy tests. Tests are affordable, generic, come individually sealed with expiration dates extending two years. also maintains a user-generated photo gallery of positive pregnancy test images.

How Soon Can I Test?

If a woman is pregnant, the amount of hCG in her system should be around 25 mIU at 10 dpo (days past ovulation), 50 mIU at 12 dpo, 100 mIU at around two weeks dpo. Blood tests can determine pregnancy as low as between 5 to 10 mIU/hCG, though with levels of 5 mIU, a conclusive determination cannot be made without risking a "false positive" (as low levels hCG can be present in the body without pregnancy).

Drugstore pregnancy tests generally detect pregnancy at 50 mIU - 100 mIU hCG, though you can find early-detection pregnancy tests on the Internet with sensitivity levels as low as 20 mIU. With all diagnostic products, take care to follow the instructions. Please consult the chart below for a comparison of pregnancy tests: 20 mIUs hCG
E.P.T. 40 mIUs hCG
Clearblue Easy 50 mIUs hCG
Store Brand: Rite-Aid 50 mIUs hCG
First Response 100 mIUs hCG
Answer 100 mIUs hCG
Store Brand: Equate/WalMart 100 mIUs hCG
QTest 100 mIUs hCG
Store Brand: Walgreens 100 mIUs hCG
Precise 100 mIUs hCG

For earliest detection of pregnancy, use first morning urine, as this sample contains the most concentrated amount of hCG. If using first morning urine is not possible, avoiding urination for several hours before using a pregnancy test. Frequent urination - or a diluted sample - can decrease the amount of hCG in your urine, interfering with early-detection.

What does a faint line on a pregnancy test mean?

On a pregnancy test, a faint test line - or color band - is usually indicative of a positive result, as long as it's read within the allotted time frame - or reaction time of the test (usually at 5-10 minutes). If you do the pregnancy test properly and read it within the recommended time, then a faint and weak line is very likely a positive pregnancy test. Explanations for a faint positive line include:

  • You may be testing too early after conception - the hCG in your body may not be at a sufficient level for test detection. hCG doubles every two days, so wait and test again using first morning urine.
  • Different test sensitivity. As tests detect hCG at different levels, a faint line on one variety of test may appear as a stronger line on a 20 mIU test.
  • Urine dilution. Your urine may be diluted due to frequent urination or consumption of liquids. First morning urine is recommended for pregnancy testing as it contains the most concentrated presence of hCG.
  • Chemical pregnancy. Sometimes, an early pregnancy is detected - followed by negative test results. A chemical pregnancy means implantation takes place followed by a miscarriage - usually before any other pregnancy symptoms are detected.

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Im really worried that I'm pregnant right now. My boyfriend and I were quite careless and stupid around the time of my ovulation, and now I'm sitting on eggshells until my period comes. I'm due in 4 days, but i've had sore breasts for more than a week now, and no signs of acne like i usually have by now. I'm really not ready to become a mother, but I should've thought about that before being irresponsible. My bf already told me that if I am, he wants the pregnancy terminated, because he's not ready either. This makes me hope even more that I'm not pregnant. I don't want to abort an unborn child, and never would I have ever imagined that I'd one day be in the position to. Im 22, and my parents would be so disappointed in me. Originally, mine as well as my parents plan, was to wait until marriage to even engage in sex. I failed miserably. Now I don't know what to do! /:(

i have been off my contraceptive pill for 3 months now, when i was on my pill i was very bad at taking it i would only take if i remember, me and my partener have nevre used protection. as soon as i stopped my period was coming like normal every month, me and my partner are trying to conceive at the moment. this month i had my period on the 9th-13th then a week later i start getting cramps really bad like i do when i am on my periods, i still have them now, light headed now and again, i have been gettin bad shooting headaches and also now my boobs have became very sensitive and sore my back hurts and, my underarms are getting achey aswell due to my boobs being sore. could i be pregnant already? should i take a test or wait until my next period? email me please

hi am ttc since 1 year my gyn put me on clomid 50 first cycle thought i ovulate normally my period is one day late should i take a pregnancy test or wait more

I have been tring to have a baby for 11 months . I got of my birth control 11 months ago an january an febuary were my only regular period since I was on birth control . Im 20 & was on birth control since I was ten . Can that cause me not to ovulate . I used an ovulation calender an it said I would ovulate on the 28 . The first day of my last period was the 16 of febuary an lasted 6 days . Me an my husband have had intercourse on the 23 , 25 , 26 & we will the 27 & the 28 , what are my chanve of gettin pregnate , if I even can :/ please help me !!

I have a question I took an early detection test when my period was about 3 days late, it came out positive and prior had all symptoms of pregnancy. Next day took another early detect test and was positive started bleeding like a period. Is there a chance I could still be pregnant?

I ovulated on the 25th august and I have had sexual intercourse during the whole time 5 days after I've noticed spotting as per some research it could be implantation research how soon can I do a test to know for sure if it is positive?

I have had sex with the same guy for 4 years and we have never used a condom and never pulled out and I just started birth control a month ago but have been on antibiotics the while time ive been on birth control can I not have kids ??

my wife has not had her periods since 29th march 2012 (1st day of last cycle)...have had protected sex with her all through...she did a pregnancy test by herself on the 1st of may with an early morning sample which turned out to be it a false negative test coz she still ha not menstruated....plz mail me...will be obliged...

tdear madam/sir
i amat 20 years i recently sex with my husband on 5 days of my period but this month my period comes after 17 days is there any problem with my body or why i not get pragnency pls advice me this is fist time ..............pls mail me

On jan 18th a urine pregnancy test came back negative. My period was scheduled to come on jan 21st but never came. Four days later i took two positive tests. Two days later, the hospital gave me two urine tests and a blood test but they were all negative. Its feb 5th and i still have no period, nauseated every day and cramping. The only pregnancy symptom im missing is sore or tender breasts. Im really confused.

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