Lastly: sometimes twin or higher order multiple pregnancies, in which levels of hCG are very high, can cause a false negative pregnancy test. This is called the high-dose hook effect. 4 It's unusual, but possible. if you miss a period and have pregnancy symptoms, see your doctor.
High levels of HCG in early pregnancy prevent antibodies from binding to the hormone, so when a test pack is checked, the results are negative. This condition is known as the prozone effect. So, getting pregnant with twins and having a negative test pack is possible.
Even if you are pregnant with twins, there's no guarantee you will produce hCG any sooner than if you were pregnant with one baby. But because your levels may be higher, it is possible to detect a pregnancy slightly earlier due to higher levels of hCG.
That said, hCG levels vary from person to person and pregnancy to pregnancy, so hCG levels are not definitive to determine a twin pregnancy. Some people have high hCG levels and only give birth to one baby; others have exceptionally low hCG levels and give birth to multiples.
Confusingly, when levels of hCG are too high, they can also interfere with pregnancy test results. This is why, interestingly, being pregnant with twins can sometimes cause a false-negative pregnancy test.
Yes, it is possible. Getting a negative result doesn't mean you're not pregnant, it may just mean your hCG levels are not high enough for the test to detect the hormone in your urine.
Specifically, twin and multiple pregnancies can have 30% to 50% higher hCG levels than singleton pregnancies at the same point in early pregnancy.
That is, the actual hCG value is higher in a twin pregnancy, but over the course of 24 hours, it will increase by about the same percent as the hCG value in a singleton pregnancy.
Range of hCG levels and what they can mean
The range for singletons is 5 – 397 and for twins it is 48 – 683. As you can see, there is a big overlap between the first hCG level in singleton and twins. What this means is that even if you have a first hCG level of 397, it could be a singleton pregnancy.
You cannot conclusively distinguish a single pregnancy from twins on a urine pregnancy test. That said, you may have a very early positive pregnancy test if you are carrying twins.
If you get a negative test result, but you still think you might be pregnant, take another test one week after your missed period or contact your health care provider.
If you feel as though you're pregnant but got a negative home pregnancy test result, your symptoms could be down to premenstrual syndrome (PMS) or you may have taken the test too early.
An immediate dark positive result could mean that there's a high concentration of hCG in your urine, and the test is showing an immediate dark result due to the hormone level. One thing to note is that all home pregnancy tests are different and may detect hCG at different levels.
Used incorrectly, used past the use-by date, or even used too early (after missing your period) are all reasons for a false negative. Not enough pee or too much pee can also produce a false negative. Even though the test is 99% accurate, the conditions need to be optimal for it to work to that standard.
Can Too Much Pee on a Pregnancy Test Make It Negative? Urinating too much on a urine pregnancy test should not cause a false negative result. But diluted urine, or urine with a higher water content, can impact a pregnancy test by skewing results.
A pregnancy test can find hCG (and give a positive result) in your urine when there is enough in your system. Traces of hCG can be found in your urine from 6 days after the fertilised egg implants in your womb (uterus).
3 WEEKS: Twins implantation
By 3 weeks, each zygote has developed into a ball of several hundred cells, called a blastocyst, and is burrowing into the uterine lining. Because they have different chromosomes, your fraternal twins may or may not be the same gender.
About one-third of identical twins split soon after fertilisation and form completely separate twins. Like fraternal twins, these twins have separate placentas. The other two-thirds split after they attach to the wall of the womb.
Typical Twin Conception
When more than one ovum is fertilized and implants in the uterus, the result is dizygotic (fraternal) twins, triplets, or other multiples. Although two fetuses develop simultaneously in superfetation, they differ in maturity, having been conceived days or even weeks apart.
Vanishing twin syndrome is evaluated to happen in 36% of twin pregnancies and in half of the pregnancies that begins with at least three or more gestational sacs.
Factors that increase the chance of twins include: consuming high amounts of dairy foods, being over the age of 30, and conceiving while breastfeeding. Many fertility drugs including Clomid, Gonal-F, and Follistim also increase the odds of a twin pregnancy.