Understanding the Timing of hCG Rise After Implantation

June 1, 2023
Rinnie George – June 1, 2023
Timing of hCG rise after implanation

If you’ve become pregnant even once in your life then you must have gone through…

If you’ve become pregnant even once in your life then you must have gone through multiple tests to detect pregnancy. The most commonly used methods include a home test kit and a blood test. Both of these tests detect a particular hormone in the blood which signifies pregnancy. The hormone is called hCG or Human Chorionic Gonadotropin.

hCG is produced by the body after conceiving. It is a very important hormone to maintain a healthy pregnancy. Throughout the pregnancy, the hCG falls and rises depending upon a lot of factors.

Implantation and hCG

The process of pregnancy can be divided into several stages and typically lasts for around 280 days or 40 weeks.

The first stage of pregnancy is called implantation when a human embryo attaches itself to the uterus. Now you might be thinking, what is an embryo

Right after intercourse the semen travels to the cervix and meets with a fertilized egg. Both of them together form a tiny baby which is called an embryo. This embryo attaches itself to the lining of the woman’s uterus, which is the place where a baby grows after 6-10 days from when the sperm and egg join together. This marks the first step in the process of pregnancy. 

implanation of hcg

Implantation is a very important stage of pregnancy. It is the time when the baby starts its life in the mother’s womb. It is also the time when most miscarriages happen. 

Along with the embryo, one more temporary organ starts developing in the mother’s body. It is called the placenta. Placenta is the organ from which all the nutrients and oxygen are delivered to the baby. Placenta also allows the exchange of gases and waste products between the mother and the baby.

After implantation occurs, hCG levels start to increase rapidly. 

2-3 days after implantation hCG can be detected in the mother’s body. However, the exact timing of hCG increase can vary from woman to woman and pregnancy to pregnancy.

In general, hCG levels will double every 48-72 hours in the first few weeks of pregnancy. 

The signs and symptoms of implantation are very similar to that of PMS. These include cramps, light spotting, nausea, tender breasts, mood swings, etc.

Timing of hCG Rise After Implantation

The timing of hCG rise depends from woman to woman. First, the fertilized egg has to implant in the uterus which takes about 10 days after ovulation. 

timing of hcg after implantation

There Are Certain Factors That Affect hCG After Implantation

The Number of Embryos Implanted

Women who go through fertility treatments such as IVF have gotten multiple embryos implanted in their uterus. This causes hCG rise and it can be detected very early in such cases.

The Health of the Pregnancy

The health of the pregnancy also affects the rise of hCG levels. In a healthy pregnancy, hCG levels rise after every 48 hours. If the hCG levels are not doubling up in the said time then it is an indication of something wrong with the pregnancy such as a miscarriage

Sensitivity of the Pregnancy Test

The sensitivity of the pregnancy test used can also affect when hCG levels are detected. Some tests are more sensitive than others and such tests detect hCG levels in the body earlier. 

Age of the Mother

Multiple studies have been conducted which had proven that in mothers with higher age, the hCG levels remain low and do not increase as much as in a younger woman’s body.

Body Weight

Weight issues such as overweight and obesity can also result in low hCG levels and can also affect the rise of hCG throughout the pregnancy.

Different Methods to Measure hCG

  • Urine pregnancy tests:

These tests are commonly used to detect pregnancy at home. They measure hCG levels in the urine and are typically most accurate a few days after a missed period. But urine pregnancy tests can frequently give false negative results and they are not as reliable as blood tests.

  • Blood tests:

Blood tests can measure hCG levels more accurately than urine tests. Blood tests are of 2 types. Quantitative and qualitative. A quantitative blood test measures the exact number of hCG in the blood. While the qualitative blood test only ensures whether traces of hCG is found in blood or not.  Out of these two, a quantitative blood test is a more reliable method to measure the hCG

  • Transvaginal ultrasound:

A transvaginal ultrasound is one where the ultrasound of the uterus is taken by inserting a probe into the vagina. The probe is secured with a clean condom for every use. However, ultrasound alone is not used to diagnose pregnancy and is typically advised in combination with blood tests.

Normal hCG Levels During Early Pregnancy

The hCG levels are affected by multiple factors as discussed earlier. Factors such as the number of embryos implanted, the age of the mother, and the timing of conception.

The hCG levels rise rapidly after implantation and they double after every 48 hours in the initial weeks of pregnancy.

This is a chart to depict the range of hCG across

Noraml hCG level During the pregnancy

In singleton pregnancies, that is women carrying a single fetus, the hCG reaches a peak at 12 weeks after which it decreases rapidly.

Abnormal hCG Levels During Early Pregnancy

abonoraml level of hcg during preganancy

Abnormal hCG levels during early pregnancy can be an indication of various pregnancy complications. Some of these complications are discussed below.

  • Miscarriage

hCG levels will not rise as expected in case of a miscarriage.

  • Ectopic Pregnancy

In certain cases, the embryo attaches itself to the fallopian tubes instead of the uterus. This case is called an ectopic pregnancy. The fallopian tubes are not sufficient to accommodate a growing pregnancy. It could be life-threatening. In such cases, the rise of hCG would be abnormal.

  • Molar Pregnancy

a molar pregnancy is a rare condition where an abnormally fertilized egg develops into a tumor. This can cause very high hCG levels and may require medical intervention.

  • Fetal Demise

if the pregnancy has ended due to fetal demise or stillbirth, hCG levels may drop or stop increasing.

  • Multiple Gestations

 in twin or triplet pregnancies, hCG levels may be higher than in a singleton pregnancy.

To diagnose these complications, doctors monitor hCG levels through blood tests. The frequency of the blood tests and the target hCG levels may vary depending on the specific complication being monitored.


In summary, Human chorionic gonadotropin, or hCG is the most important hormone for detecting pregnancy. Implantation marks the stage where the fertilized embryo attaches to the uterus wall, and hCG levels commence a rapid rise. However, the exact time frame of this increase is unique to each woman and pregnancy. Factors that affect the rise of hCG include the number of embryos implanted, the age of the mother, miscarriage, ectopic pregnancy, etc.

Understanding the timing of hCG rise after implantation is crucial for women who are trying to conceive or who are already pregnant. hCG is the hormone responsible for confirming pregnancy and its levels can indicate the health of the pregnancy.

By knowing when to expect hCG levels to rise, women can better interpret the results of pregnancy tests and monitor the progression of their pregnancy. Understanding the factors that affect hCG is not only important to continue the pregnancy but it is also important to figure out exits in case of abnormalities.

  • https://obgyn.onlinelibrary.wiley.com/doi/10.1111/aogs.12471#
  • https://www.mayoclinic.org/diseases-conditions/premenstrual-syndrome/symptoms-causes/syc-20376780#:

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