Miscarriage And hCG Levels: Does Dropping hCG Levels Mean Pregnancy Loss?
HealthcareOnTime Team
2024-02-15
2024-02-16
3 Min Read
Miscarriage is a condition where the mother suddenly loses the pregnancy, mostly before the 20th week, owing to certain abnormalities in the development of the fetus. Around 26% 1 of women experience miscarriage in their first trimesters, and some even later.
These include both unknown as well as positive tested pregnancies. While there are several factors (some constant while others are subjective) behind miscarriages, researchers have correlated dropping HCG levels with the future of pregnancy 2. This is because lower HCG levels have been a common symptom during miscarriage.
But that doesn't mean the lack of the hormone is the only potential reason for miscarriage, and the latter can have various other reasons, too. Are you in your initial stages of pregnancy with a low HCG level? That's not always a red flag. In fact, here's what you need to know about the interrelationship between HCG, pregnancy, and miscarriages.
What is an HCG Test?
HCG tests check the presence and quantity of the hormone in your urine. While most home urine test kits detect the presence of HCG, you might need a quantitative HCG test for more precise results. Moreover, HCG tests are taken twice within 48 hours in some cases to check the growth of the hormone and rule out any anomaly in the same. The doctor might ask you to rethink your pregnancy if the HCG levels do not double up or increase significantly, or even decrease within the phase of the test series, as it indicates a stunted growth of your embryo.
What is HCG Levels in Pregnancy?
HCG, commonly called the Human Chorionic Gonadotropin, is a hormone that your placenta produces once you conceive. Doctors also call it the "pregnancy hormone" because it helps in the nourishment of the egg so that it can grow. You can find this hormone from 11 days after you conceive and also measure it using an HCG pregnancy test. This test measures the presence of the hormone in 1 milliliter of blood to check if the levels are normal.
Normal HCG Levels in Pregnancy
Your HCG levels will rise within 48 hours of implantation. So, you can see a change in HCG levels within two days after the egg attaches itself to the uterus. And this hormone generally doubles up every 48 hours in the first 8-11 weeks of pregnancy. Here are the following correlations between HCG and the growth of pregnancy 3-
- 800–1,500 (UI/L) of hCG: Gestational sack is visible
- 4,500–7,500 IU/L of hCG: Yolk sack is visible
- 8,650–12,200 IU/L of hCG: Heart movements of the fetus are visible
Apart from these major phases throughout your trimesters, here is an overall count of normal HCG levels in your bloodstream based on your week of pregnancy 4-
Abnormal HCG Level Trends
The HCG levels mentioned above show the normal count during the course of pregnancy. If your doctor finds dropping HCG levels beyond these levels or remaining the same, it might mean your fetus has some complications.
For instance, if your HCG levels in pregnancy drops from 120 mIU/mL to 80 mIU/mL or it only rises to 130 mIU/mL in two days, it means that your body is not producing enough hormone to nourish the embryo.
It is important to note that falling HCG levels might not indicate an obvious miscarriage in all the cases. Instead, doctors take it as one of the many indicators in determining a successful pregnancy.
In fact, sometimes lower HCG levels might also indicate unviable pregnancies, even if they do not necessarily lead to obvious miscarriages.
What Causes Low HCG Levels in Pregnancy?
There might be a couple of reasons for having low HCG levels in pregnancy. Does that mean you will surely have a miscarriage? Not always. Of course, there is a possibility of having stunted growth in the embryo, but here are some other possible reasons for low HCG levels:
- Blighted ovum: In this situation, the egg does not develop after attaching itself to the womb. Naturally, the HCG levels do not rise since the egg doesn't grow, and it occurs in the early few weeks of pregnancy.
- Ectopic pregnancy: This is an unusual kind of pregnancy where the egg doesn't attach itself to the womb and keeps growing in the fallopian tube. It is a life-threatening pregnancy because it could lead to the rupture of the fallopian tubes, causing immense blood loss. Low HCG levels can often indicate an ectopic pregnancy.
Miscarriage and HCG Levels
HCG Levels After Miscarriage
HCG levels after miscarriage keep dropping and generally return to normal levels within 4-6 weeks, depending on the stage of pregnancy. Thus, mothers who experience miscarriage in the early stages of pregnancy generally get back to the pre-pregnancy HCG levels sooner.
HCG Levels During Miscarriage
HCG levels keep dropping consistently during miscarriage. While this isn't the only indicator of pregnancy loss, it can be one of the important markers of the same. If your HCG level doesn't double up every 48 hours in the first 8 -11 weeks of pregnancy, your doctor might ask you to take two HCG tests 48 hours apart from each other to study the trends. In fact, serial testing of HCG levels can be a great way of tracking the production of the hormone. In cases of miscarriage, HCG is generally found to remain the same or even decrease.
While a slow rise in HCG levels might be subjective to each pregnancy, doctors consider a growth rate of less than 35% 4 in 48 hours to be significantly slow and declare it as an "unviable pregnancy."
Do Low HCG Levels Necessarily Mean Miscarriage?
While researchers and doctors have often connected low HCG levels with pregnancy loss, it is not a definite marker of the same. While on the one hand, HCG levels are expected to double up 5 in the first few weeks of pregnancy, women also have successful and healthy pregnancies with lower levels.
However, in most cases, low HCG levels do indicate some underlying problems in the pregnancy. Additionally, low HCG levels along with the following symptoms might indicate miscarriage:
- Spotting
- Pinkish vaginal discharge
- Sudden vaginal bleeding
- Abdominal cramps
It's worth mentioning that while you can track your pregnancy progress with serial HCG tests, the confirmation usually comes from an ultrasound scan when you can actually see the baby. Sometimes, additional tests like a transvaginal ultrasound or tests to check progesterone levels are also help in checking HCG levels.
What are the Other Causes of Miscarriage?
Some of the most common causes of miscarriage are as follows-
- Irregular chromosomal conditions: Nearly half to two-thirds of the total pregnancies suffer from miscarriages because of extra or missing chromosomes 5. During conception, the sperm fertilizes the egg and there are two sets of chromosomes coming from each parent. When this chromosome pairing is abnormal, it might lead to miscarriages.
- Molar pregnancy: Molar pregnancy is a kind of pregnancy where the sperm alone provides both chromosomes. Hence, the embryo is unable to receive the necessary configuration of two sets of chromosomes from two parents. There is no development of the fetus in such a pregnancy owing to the stunted and abnormal growth of the placenta.
- Diabetes: If you are suffering from diabetes, there are chances of excess amniotic fluid affecting your placenta. This might affect the growth of the fetus and increase the chances of miscarriages or stillbirths 6.
- Obesity: A higher Body Mass Index has often been connected to an increased rate of miscarriage 7. In fact, researchers have not just found a higher incidence of miscarriage in obese women but also a greater chance of repeated miscarriages in them.
- Cervix or uterus issues: Also known as "incompetent cervix", it is a condition where the cervix opens up early in the pregnancy, increasing the chances of miscarriage. On the other hand, if your uterus wall is too thin, it fails to hold your fetus as it grows, finally leading to miscarriage.
How to Confirm a Miscarriage?
If you think you had or might have a chance of miscarriage, you might opt for taking the following tests to rule out any such possibility.
- HCG Pregnancy Test: You can take an HCG Pregnancy Test to determine the condition and growth of your embryo. HCG tests are generally conducted twice within 48 hours to map the change in its levels. If the doctor finds slow or dropping hCG levels, it might mean abnormal or stunted embryo growth.
- Other blood tests: Apart from HCG tests, there are other blood tests for pregnant women that check their progesterone levels, the presence of any dominant or recessive traits that might manifest in your fetus, and much more.
- Pelvic exams: Pelvic exams are often suggested by doctors to check the opening of your cervix, and if the opening is larger than usual in the initial days of pregnancy, the chances of miscarriage are higher.
- Tissue tests: If you have already started getting cramps or sudden vaginal bleeding and notice tissues passing out, you can also send that for testing to confirm whether you had a miscarriage.
Conclusion
It is important to note that miscarriages most definitely reduce HCG concentration as the hormone is only found when you are pregnant. Thus, your hCG levels can keep dropping with pregnancy loss and gradually come to the baseline. However, it is false to assume falling HCG levels most definitely lead to miscarriages since the former is a symptom of the latter and not an underlying cause.
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