However, home pregnancy tests won't confirm if twins are present, only the presence of hCG. It takes around 2 weeks after conception for hCG to be detected in a hCG pregnancy test. Low levels of hCG may be detected in a woman's blood 8-11 days after conception.
Early signs of a twin pregnancy include severe morning sickness, quick weight gain, and more breast tenderness. You may also notice an increased appetite or extreme fatigue. Plus, those who have a twin pregnancy may begin showing sooner.
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.
Specifically, twin and multiple pregnancies can have 30% to 50% higher hCG levels than singleton pregnancies at the same point in early pregnancy.
The hook effect is uncommon. Researchers suggest that it occurs in 0.2–2% of immunoassays, which are medical laboratory tests that use antibodies to detect specific substances or analytes. Laboratory technicians often use sandwich assays .
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.
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.
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.
In the first few weeks of your twin pregnancy, you might notice some typical signs of early pregnancy, such as breast tenderness, fatigue, nausea, and a missed period.
Implantation pain
Feeling those implantation pains during the first trimester? It could be twins, but if you're not sure or you're worried about the pain, make sure you get this one checked out by your midwife or doctor.
Week 4 of pregnancy
For example, a fertilised egg may have implanted in your womb just 2 weeks ago, but if the first day of your last period was 4 weeks ago, this means you're officially four weeks pregnant! Pregnancy normally lasts from 37 weeks to 42 weeks from the first day of your last period.
Fraternal Twins: This type of twin set is the most common. This occurs when two different eggs are both fertilized by two different sperm and implant themselves into the uterine wall at the same time. Fraternal twins will both have a different amniotic sac and placenta.
Signs of a twin pregnancy could include feeling early pregnancy symptoms more intensely, but there isn't really any way to really know you're pregnant with twins until two babies are seen on an ultrasound.
Pregnancy Tests
It's too early to take a home pregnancy test in week 3. But, by the middle or later part of next week, you might be able to detect the pregnancy hormone hCG in your urine with a sensitive early test.
3 weeks is usually too early to take a test if you want the most accurate result. Some women, however, will get a positive result by the end of this week. Although you might be desperate to find out, if you think you could be pregnant it's best to wait until next week.
If the test result is 'Pregnant' a numerical result: "1-2", "2-3" or "3+", is also displayed indicating that conception occurred 1 to 2 weeks ago, 2 to 3 weeks ago or 3 or more weeks ago.
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.
In many cases, you might get a positive result from an at-home test as early as 10 days after conception. For a more accurate result, wait until after you've missed your period to take a test. Remember, if you take a test too soon, it could be negative even if you're pregnant.
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.
The strength of the positive test line depends on how much hCG is in your urine. If the line is faint, it usually means that the hCG level is low. One reason why hCG levels may be low could be because you're still very early into your pregnancy.
The earliest you're likely to find out for sure is between 10 weeks and 14 weeks, when you have your dating scan (NHS 2022a, NICE 2019a, Twins Trust 2021). Ultrasound is almost foolproof at diagnosing a twin pregnancy .
If you're 30 or older, you're more likely than younger people to release more than one egg during a menstrual cycle. You have relatives who have had multiples. If you or other people in your family have had fraternal twins, you may be more likely to have twins, too.
Twins are more or less equally likely to be female or male. Contrary to popular belief, the incidence of twins doesn't skip generations.