February 27, 2024
hcg levels twins

HCG Levels in Twin Pregnancy

There are some mothers who suspected they are having twins before they knew for sure. Other mothers are caught completely off-guard when they learn that they’re carrying twins. Even though there are a number of symptoms and signs that can indicate twin pregnancy, there is also a lot of similarity between them and those moms having single pregnancies. It’s quite typical for mothers to have a lot of questions about HCG levels twins. There are some differences between carrying twins versus carrying only a single baby and this is likely to make those mothers have more questions. The first and most obvious is simply, “How are they different?”

Questions about HCG levels as well as what symptoms or signs to look for in a twin pregnancy and other factors that may raise HCG levels are some of the things discussed here.

What Is HCG?

HCG or human chorionic gonadotrophin is a hormone that is present when a woman is pregnant. It is what is detected in the blood or urine when a woman takes a pregnancy test. Because the tests are sensitive to even small amounts of HCG, it means that, if any amount is found, it can indicate that the woman is pregnant.

This hormone is needed to help produce estrogen and progesterone in the woman’s body until the placenta is more fully developed. Once that takes place, then the placenta will take over.

The HCG is made by the body when fertilization takes place in the mother. It provides nourishment for what will become the embryo. This also tells the body that it doesn’t need to menstruate because it is preparing to grow a baby.

How High Are HCG Levels in Pregnancy?

A woman who is pregnant will usually have at least 25 mlU/ml of HCG. If they have less than 5 miu/ml, then the pregnancy test will read negative. HCG is typically measured by milli international units per milliliter (mlU/ml). The main thing that is important is how much of an increase in this hormone has taken place because it’s an indication of pregnancy.

The measurement of HCG also helps show that the body is working in a way that will fully support the development of the embryo. It is possible that a woman could get a false negative reading simply because she tested too early in the pregnancy and the level of HCG hadn’t risen enough. In other cases, if there wasn’t enough blood or urine or they were somehow diluted, then it could produce a negative reading.

One of the reasons why some home pregnancy testing kits provide two test strips is to reduce the number of false negatives a woman might experience. This allows a woman to easily check a second time to make sure the reading was correct. There are two different types of tests that measure HCG. One type, a qualitative test, detects the presence of this hormone, while the quantitative test measures the exact levels of the hormone found in the blood or urine.

When Does the Body Begin Producing HCG?

For most women, this hormone starts being produced very soon after fertilization has taken place. The process produces this from cells that ultimately become the placenta. If a woman becomes pregnant, she will begin producing HCG even before she misses her first period.

Very often, this hormone can be detected in as little as one week after ovulation. In most cases, it is recommended that a woman wait about 11 days past the time she thinks she may have conceived to take a blood test for this hormone. If using urine, it may take up to 14 days to detect this hormone.

The HCG levels are often very different in women who have twins versus a woman who has only one baby. But to what extent there is a difference will depend on different women and the stage of pregnancy they are in when tested.

If a woman wants to test as early as possible, she will need to go with a blood test in lieu of a urine test because it’s possible to test earlier. If she chooses a urine test, then she will want to use the first urine of the morning because it is the most concentrated.

Why Test for HCG Levels?

The main reason for this test is to determine if a woman is pregnant or not. Later in a pregnancy, the levels of this hormone can be tested to see if there are any problems with the pregnancy. It can sometimes help a doctor determine if there is a risk of miscarriage.

It is also possible to use this test to help determine if there are low levels of a certain type of protein which can mean the baby is more likely to have Down syndrome. If a woman is scheduled for certain types of medical treatments, then it might be necessary to screen her to make sure she is not yet pregnant.

The medical treatments may put the pregnancy at great risk and therefore the doctor will want to make sure she’s not pregnant. The doctor will usually have a blood test done in this type of situation.

What Role Does the HCG Level Play in Twin Pregnancy?

The primary job of this hormone in a woman who is carrying twins is to communicate to parts of the body that play a role in the development of the embryo. This process helps to maintain the corpus luteum and that in turn produces the secretion of hormones that the woman needs.

All of this works together in the uterus to provide support for the embryo so that it develops properly. The lining of the uterus provides essential nutrients to the embryo as well as oxygen until the placenta is fully formed.

Understanding the HCG Levels in a Single Pregnancy versus a Twin Pregnancy

hcg levels twins

A woman will almost always have a higher level of HCG when she is carrying twins than she will if she has only one baby. This is not always the case and there are a number of factors that are very similar between a woman with twins and a woman with a single pregnancy. Trying to compare is not always as helpful as you would hope.

Women do not usually know what their HCG levels are and so they won’t know if it’s high. What they will be able to know is whether or not they’re actually pregnant based on their own judgment or through the process of having their judgment confirmed with a home pregnancy test.

These tests will usually not give an exact reading of the levels of HCG because they are designed to simply test for the presence of this hormone. It’s pretty normal for a woman with twins to have levels of this hormone that are 40% higher or more than those who are carrying only a single baby.

But the amount of HCG may not have risen to this level during the time that the woman first notices that she has missed her period. This hormone can vary significantly from one woman to another as well as from one pregnancy to another. Research studies have found huge differences between women and that was true even when it was between several women who were all carrying only a single baby.

How Often Does HCG Increase?

Early in a woman’s pregnancy, this hormone can increase every couple of days and during that time it can go up as much as 60% but these increases only take place in the early stages of pregnancy. The majority of pregnancies will see levels of HCG double about every three days or so.

Somewhere around eight to ten weeks, these levels will begin to peak and then they will begin declining. If HCG goes up by about 35% during the first 48 hours, that is considered normal. It will usually take up to 96 hours for this hormone to double.

The further along your pregnancy is, the more this hormone will start slowing down. Once your HCG reaches 6000 milli international units per milliliter, then it will usually take four or more days for it to double. The yolk sac should be seen once these levels reach 7200 mIu/ml.

When the level of HCG in the body reaches 10,800 mIu/ml, then the embryo should have a heartbeat. The further along the pregnancy is, the more these levels stop increasing. This decrease in the production of this hormone is one of the main reasons why morning sickness, which is typically experienced early in the pregnancy, goes away as the woman enters the later stages of pregnancy.

Does a High Level of HCG Mean That I Am Going to Have Twins?

No, not always. There are various reasons for these high readings. Keep in mind there are wide differences in what is considered normal in terms of HCG levels. This level should also not be used for estimating pregnancy gestation because they often vary widely and are inexact.

A single isolated reading will not offer accurate information about the status of your pregnancy. If you have any doubts, various tests conducted over 3 to 4 days will offer more insight into whether the pregnancy is viable.

In addition, it is close to impossible to distinguish twins from a single pregnancy on just a urine-based pregnancy test. With this in mind, you might get a positive result on a pregnancy test much earlier if you are pregnant with twins. When using one of the standard pregnancy tests that are not super sensitive and you achieve an instant positive a couple of days before you expect your period, this may be an indication that you are expecting twins.

Yet it is important to understand that the home tests are not as reliable when predicting HCG levels as they are simply designed to measure whether there is HCG present or not. This may mean that there is a probability that a dark or early positive test result might be linked to not drinking enough water when you took this test.

The blood pregnancy tests, on the other hand, that test for HCG levels might give you a better, yet still inconclusive hint as to whether you may be pregnant with twins. In any case, HCG levels that are elevated in the earlier stages of pregnancy are not the correct method for detecting twins.

One of the reasons is that HCG levels are not checked regularly unless you happen to be on a fertility treatment plan. Even when there are twins present, this is not a guarantee that you will be producing HCG any sooner or faster than when you are only pregnant with a single baby.

Yet because the levels are higher, it becomes possible to determine a pregnancy a bit “earlier” because of the HCG spike.

Signs and Symptoms of a Multiple or Twin Pregnancy

There are a number of symptoms and signs linked to potentially carrying twins. A few are anecdotal and symptomatic, while others are scientific.

1. Weight gain

While mothers who carry twins usually only gain around 10 pounds more compared to the singleton moms, the weight that is gained by a woman is often more dependent on her body type, height, and what she weighed before pregnancy rather than how many babies she is carrying.

At the same time, most of the weight gain happens in the later stages of the pregnancy, often once an ultrasound has excluded or confirmed the diagnosis already.

In addition, the way you are eating may also be the reason that you are gaining excessive weight. You may be consuming a lot more calories than needed. If you are worried about the weight you are gaining while you are pregnant, do not hesitate to talk to a doctor who can refer you to a qualified prenatal nutritionist.

2. Excessive morning sickness

Certain people agree that twins make mothers-to-be “twice as sick and three times as tired.” It has been proven statistically that mothers that are carrying more than one baby are prone to experiencing morning sickness that is amplified, yet this differs from one mother to the next.

For example, even the mothers that are only carrying one baby can also experience excessive morning sickness. About 50% of all pregnant moms will experience some form of nausea and morning sickness, regardless of how many babies they are carrying.

3. Doppler heartbeat count

The Doppler system makes use of sound waves (non-invasive) that amplifies the heartbeat of a fetus in the 3rd trimester. Technicians that are experienced can usually detect more than one heartbeat in a test when present.

This test is not entirely accurate in detecting a second or third heartbeat, as it could be a single baby’s heartbeat that is echoing or when it is heard from different angles.

4. AFP screening

The alpha-fetoprotein (AFP) screening is usually performed in the 2nd trimester that measures for specific birth defects and a marker for twins. You might be pregnant with twins if the result is unusually high or positive.

5. Measuring large for the gestational age

Throughout pregnancies, midwives or doctors measure the uterine fundus height (which is a measurement from the top of your uterus to the top of your pubic bone). This is used to estimate the gestational age and how the baby is growing.

A multiple or twin pregnancy might cause the uterus of the mother to increase beyond the normal range of pregnancy of one baby. However, there are other factors which can contribute to an increase in these measurements. These measurements are more difficult in the earlier stages of pregnancy compared to later stages when ultrasounds might already detect twins.

There is also a chance for you to measure larger or “show larger or sooner” than usual if you have been pregnant before. You can also measure larger when the conception date was inaccurate or the baby is bigger.

6. Fetal movements

Feeling your baby or babies move in the womb happens to be the most exciting part of any pregnancy.

The very first time you feel the baby move, which is called “quickening,” usually occurs from 18 to 25 weeks but is typically detected earlier in a subsequent pregnancy, sometimes as early as 16 weeks. When a woman feels movements in the earlier stages of pregnancy, it is in most cases inconsistent and may be deceiving.

Even though there are a lot of mothers of multiples who experience earlier and more frequent fetal movements, there is a degree of disagreement among medical professionals about this subject.

For certain women, movements that are recognizable occur during the early stages of subsequent pregnancies, regardless of whether they are carrying a single baby or twins or multiple babies. It is also important to be aware when you may mistake a fetal movement for an upset stomach or gas.

7. Hunches and gut feelings

While what we previously mentioned refers to some form of evidence that is visible, we cannot disregard how powerful a mom’s intuition is.

Whether the mother-to-be has a hunch or has dreamt about having twins, those who care for pregnant moms quickly learn when to listen. Some of the better “hints” that indicate a multiple or twin pregnancy is not easy to explain in the medical textbooks.

8. Severe fatigue

Fatigue that becomes extreme is the more common complaint that is reported in multiple or twin pregnancies. Exhaustion, lethargy, and sleepiness in the 1st trimester can increase as the body works overtime in order to nurture the babies.

In certain cases, fatigue is linked to other aspects such as looking after other children, poor nutrition, stress, and work. Yet it can also be an indication of multiples. The fatigue level is usually complex to assess, especially if it is relating to twins.

It is common that fatigue is inevitable during pregnancy, even for the moms of single babies. Keep in mind that first-time mothers do not have a point of reference as to what is regarded as a “normal” level of fatigue.

The second and third-time moms may notice an increase in fatigue but usually attribute this tiredness to demands of keeping up with caring for their other children while they are pregnant. Once again, fatigue is a symptom that is subjective and is associated with a number of other potential culprits.

How to Confirm That You Are Having Twins

The only real way to confirm a multiple or twin pregnancy indisputably is to see the baby or babies using an ultrasound. This is an image which is able to detect without any doubts when there is more than a single fetus present.

It is highly unlikely that an ultrasound will miss the presence of another baby, especially when conducted in the 2nd or 3rd trimester. During your ultrasound, which takes a video and photo of what goes on inside your uterus, your caregiver or doctor will see more than one fetus or hear more than one heartbeat, which will confirm whether you are pregnant with one or multiple babies.

Hidden Twins

In some very rare cases, even ultrasounds might not show clearly that there is a twin present. However, it is very unlikely that an ultrasound will not detect another baby after 20 weeks.

In these occasions, the 2nd fetus did not magically appear on its own, but rather it was hidden in the original image, which is not an overall view of your womb which may hide the other baby.

More specifically, a “hidden” twin is more common with an early ultrasound if the babies are monochorionic (identical) twins. In certain cases, extreme multiple pregnancies, which include sextuplets or quintuplets, are complex to count or distinguish in the ultrasounds before 20 weeks.

What Can Affect Your HCG levels?

There is often another reason or reasons as to why HCG levels are high—other than carrying twins or multiples. When a woman takes fertility medications, the HCG levels increase. One of the other common reasons that explain high HCG levels is due to a complication in the pregnancy known as a molar pregnancy.

1. Molar pregnancies

Also known as GTD (gestational trophoblastic disease), this is a rare condition that is known to occur in about 1 out of 1,000 pregnancies. It arises when there is an issue during the stage when the sperm and egg join together and fertilize which results in abnormalities inside the placenta.

A molar pregnancy is usually either complete or partial. In a complete molar pregnancy, there will be placental parts that are present, but there will be no baby. This is because of an empty egg and no baby will develop. The partial molar pregnancies occur when a mass contains abnormal cells and an embryo that will have major birth defects.

When this occurs, the fetus is quickly overcome by the abnormal mass that continues to grow. In some cases, when 1 of the embryos is growing normally and the other embryo is molar, the healthy and normal embryo will also be consumed by this abnormal growth. Women that are older than 40 who have had a previous molar pregnancy or a miscarriage are at a higher risk of molar pregnancies.

The symptoms associated with molar pregnancy include vaginal bleeding or spotting, vomiting, nausea, the development of thyroid disease or other uncommon complications, increased HCG levels, early preeclampsia, and no fetal heartbeat or movement will be detected.

2. Genetic complications

HCG levels that are low are sometimes experienced due to a genetic complication which leads to a miscarriage or ectopic pregnancy. It often results in a terminated or troubled pregnancy.

3. Infertility treatments

In most cases, HCG is used in injection form as part of a treatment plan for infertile women. This will also increase the HCG levels.

4. Genetic defect

HCG levels that are extremely high can be related to a genetic complication during the stage of fertilization. This can result in the baby having a condition such as Down syndrome. Molar pregnancy might also occur when the placenta starts to grow into a mass of abnormal cells which leads to what is known as a mole. Whether or not the fetus is detected, it will die as a result.

5. Influencing factors

A pregnancy test that is performed later on in a day or very early in the pregnancy can lead to a false negative pregnancy result. The more accurate result can be derived in the early morning with the 1st urine of the day.

6. Cancer

Cancer present in the large intestine, pancreas, lungs, liver, stomach, and uterus can also increase HCG levels.

What Does It Mean If the HCG Levels Do Not Go Up?

When HGC levels do not increase during the stages of early pregnancy, more specifically in the first 8 to 10 weeks, then the mother should go for a blood test. When the result shows an HCG level that either stayed the same or dropped, then it might be an indication that her pregnancy might not be progressing normally.

To make sure, the doctor will usually correlate an HCG test result combined with an ultrasound. In most cases, doctors expect to find evidence of the pregnancy using ultrasound when the HCG levels have reached between 1,000 and 2,000 IU/L.

If the gestational sac cannot be seen during this time, this is usually concerning. When this occurs, a consultation with a doctor is needed urgently.

Progressing through pregnancy with a clear understanding of how HCG levels work for singletons and twins has its own advantages. It provides a clear picture of what to expect and usually makes any mom more prepared and stronger.

Frequently Asked Questions (FAQs)

1. Why did I receive a positive result on my test so early? Does this mean I might be carrying twins?

An early positive result may be an indication that you are carrying twins, yet this is not something to rely on.

The pregnancy tests done from home can detect the presence of HCG (human chorionic gonadotropin) in your urine. Levels of this hormone are definitely higher in a twin or multiple pregnancies, yet not straight away. It will take a couple of days for HCG production of more than one baby to outpace HCG production for just a single baby.

In fact, when you reach the 1st day of a missed period, there may be no difference at this stage. Since you conducted the test yourself before that, it is likely that what was measured is just a standard variation in the production of hormones.

An early positive can also mean you are carrying two or more babies (more common in women over the age of 35) or it could also mean that you are only carrying one. The only thing you can confirm at this stage is that you are indeed pregnant.

2. I am 18 days past ovulation (DPO) while my serum hCG is 556. Does this mean that I might be expecting twins?

Having a serum HCG of 556 mlU/mL at 18 DPO is normal for both single and twin pregnancies. You may be pregnant with twins, yet you cannot know for sure from just a serum HCG value. At 18 DPO, serum HCG for a single fetus is typically between 70 and 750 mlU/mL, and in twins, it can range from 200 and 1750 mlU/ml.

3. What will affect my chances of falling pregnant with twins?

There are many factors which may have an influence on the likelihood of you having more than one baby. Fertility treatments like IVF (in vitro fertilization) will increase your chances of multiples or twins.

Because twins result from the fertilization of multiple eggs at the same time, an older woman who falls pregnant has an increased chance of falling pregnant with twins when they are releasing two or more eggs at the same time due to age.

Genetics and family history also play a role, particularly when twin pregnancies were not a result of fertility treatments. Specific types of lifestyles and falling pregnant in certain locations is also suggested to increase the likelihood of twins.

4. Am I carrying twins for sure when HCG levels are increasing too fast?

In the majority of pregnancies, HCG rise which is regarded as normal is a minimum of 60% over a period of 48 hours. If there are twins present, these levels can rise a lot more, yet it is usually not possible to determine twins just from HCG levels. For example, HCG can rise significantly even in a single pregnancy.

There is not enough scientific evidence that when pregnant with twins there will always be a rise that is faster than usual in HCG. The normal HCG values often vary as much as 20 times in a normal pregnancy. The variations in the increase in HCG is not always a sure sign that your pregnancy is either abnormal or that you are carrying more than one fetus.


Having higher amounts of HCG in urine may be an indication of multiple pregnancies or twins, yet this is not always the case. Levels of the hormone will vary across pregnancies and from one mom to the next.

HCG levels go through many variations in both single and twin pregnancies and can become an important element in indicating twin pregnancies. Yet it is not the only factor that indicates you are going to have twins because a rise in HCG levels may be associated with other types of conditions.

If you have just found out that you are pregnant and you think that it may be twins due to high HCG levels twins, ask your OB to conduct further tests in order to deny or confirm this. Keep in mind that a single HCG reading will typically not provide sufficient information in order to conclude an accurate diagnosis.  A number of additional tests will offer a picture that is more accurate.

At the end of the day, when you find out that you are carrying twins, it is normal to experience different emotions which usually include panic or excitement.  Make sure you talk about your symptoms with a doctor along with your concerns or any questions that you may have about risks involved when having a multiple or twin pregnancy.


Helen is the founder and chief creative officer of ParentsList. Helen is a mom of three, two boys and a girl, her youngest. She’s a stay-at-home mom who just happens to love writing on the side. She loves spending time with her children, especially on warm, cozy Sunday afternoons when everyone’s just relaxed and enjoying each other’s company.

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