Are you experiencing some spotting and wondering whether it’s an implantation bleed? Maybe your period is a day or so late and you think you may be pregnant? Are you considering how soon to do a pregnancy test after implantation?
When you’re trying to become pregnant, the temptation might be to do a pregnancy test earlier than you should. This can often lead to false results and disappointment. Playing the waiting game is hard, but there are good reasons for holding off that test for a couple of days.
Let’s look at what a pregnancy test detects and how soon after implantation this could be done.
What Is Implantation?
Following fertilization, the egg travels down the fallopian tube to the uterus. The uterine lining, or endometrium, is ready to accept the fertilized egg. This journey usually takes about six to eight days to happen.
On reaching the waiting uterus, the egg attaches itself and then burrows its way into the lining, preparing to grow. This implantation takes a few days to complete and can sometimes cause a slight bleed (1).
Is It an Implantation Bleed or a Period?
It’s important to note that not all women will experience signs like bleeding or cramps indicating implantation has happened. Every woman and every pregnancy is different.
- Discharge or spotting from an implantation bleed will generally be dark brown or pinkish: The bleed from a period will often be a vibrant red. There are usually no clots associated with implantation bleeding.
- An implantation bleed will only last from a few hours to a few days, while the egg attaches itself: It will usually be light and can stop and start. Bleeding that starts off light then gets heavier and lasts for four days or more will generally be your period.
- Implantation bleeding will generally happen roughly ten days after ovulation: A period will usually be 14 days after.
- Cramps associated with implantation are mild and go away quite quickly: Those associated with a period will be stronger.
What Happens After Implantation?
Let’s explore what happens with hormones after the ovary releases an egg.
During a woman’s monthly cycle, an egg leaves the ovary and the shell that contained the egg remains, called the corpus luteum. This is responsible for releasing the hormones estrogen and progesterone. It’s the progesterone that we’re interested in here, as it signals that the lining of the uterus to prepare itself to receive a fertilized egg.
If the egg does not implant, the progesterone levels drop again and the uterine lining comes away, resulting in your monthly bleed roughly two weeks after ovulation.
If implantation happens, then the uterus needs to signal the corpus luteum to continue producing progesterone to maintain the uterine lining. This is done by the newly forming placenta releasing a hormone called “human chorionic gonadotropin” or hCG.
All women have small traces of hCG in their bodies at all times, but after implantation, these levels rise and it is this hormone that is tested to indicate a pregnancy.
The amount of hCG normally found in the body won’t be enough to give a positive test. However, during the first eight weeks of pregnancy, hCG levels double every couple of days (3).
So while the waiting game might not be an easy one, just a few days can make a difference between a positive and negative test.
Methods of Pregnancy Testing
There are two ways of testing for hCG levels, either via urine or blood.
1. Urine Tests for hCG
Home pregnancy tests have improved over the years and are now sensitive enough to detect small amounts of hCG in your urine. The sensitivity of the test is indicated on the packaging as an amount in mlU/ml (milli-international unit per milliliter).
The lower the number of mlU/ml, the more sensitive the testing kit is. The range is usually between 10mIU/ml and 50 mIU/ml.
However, that is unusual and it generally takes about 10 or more days after ovulation for a test to show a positive result.
Even using the most sensitive of these tests, there might not be enough hCG to be detected yet. This can result in a false negative test which may be upsetting.
If you do have a negative test, wait a few days and test again. Your urine hormone levels might have risen enough for the test to detect.
2. Blood Tests for hCG
hCG is found in your blood a lot sooner than in urine. A positive test might be detected as soon as six to eight days after conception.
You would need to visit your doctor to have a blood test, but they will likely advise you to wait till after your missed period.
Even if you do a home pregnancy test and get a positive result, your doctor may still do a blood test to confirm this.
How Soon After Implantation Should I Take a Pregnancy Test?
There is no definitive time for when you should take a pregnancy test after implantation. While you can take a test as soon as the first day of your missed period, it might be better to wait a week more. Many factors come into play as to how accurate the result might be.
You might have conceived at the beginning of ovulation. In this case, you will likely get a positive test earlier than if you conceived at the end of ovulation.
You might not know that implantation has taken place. Not all women experience an implantation bleed or any other symptoms indicating that it has taken place.
There are also times when a negative test might happen even if you are convinced you have had an implantation bleed. These include ectopic pregnancies and tumors.
Many women have irregular cycles due to stress, illness, or normal fluctuations. Timing can be unpredictable even if your periods are regular. Nearly 70% of women reach their fertile window earlier or later than expected. This will impact when hCG is detectable in your urine. If you ovulate one week later than anticipated, you will need to wait an extra week to get a positive pregnancy test (5).
Editor's Note:Caitlin Goodwin, MSN, RN, CNM
What looks like an implantation bleed is sometimes unrelated luteal phase spotting caused by a second surge of estrogen. Many women experience this completely normal spotting without being pregnant, and many women become pregnant and never experience any implantation bleeding.
False Negative Pregnancy Tests
When you’re trying to get pregnant, the urge to do a test can be hard to resist. If you take a test and get a negative result, you could still be pregnant. Some reasons you might get a negative result are (6):
- You tested too early: The hCG levels in your urine might not have risen enough to be detected in your urine yet. Ideally, you should wait about seven days after a missed period to do a test. This way the levels of hCG will have increased and that much waited for “you’re pregnant” indicator will be there.
- You checked the test too soon: Follow the instructions carefully on the test and give it the time needed, usually a minute or more, to do its work.
- Your urine was too diluted: The best time to take a test is with your first urine of the day. The hCG levels will likely have built up overnight and can be detected easier.
Wait a few days and test again, particularly if you tested before or soon after a missed period. If you feel you are pregnant and are still getting negative test results or still don’t get a period after a week, then see your doctor.
The doctor will probably do a blood test or an ultrasound scan to confirm a pregnancy or help discover the cause of your missed period.
To Test or Not to Test
Many pregnancy tests claim to be accurate from the first day of your missed period, or even earlier. This might not always be the case and you only put yourself through the unnecessary upset that comes with a negative test.
Everyone differs in how quickly or how much hCG they produce after implantation, so now is the time to practice patience Try and resist peeing on that stick, even though the little devil on your shoulder will be whispering in your ear, “do it.”