Modern surrogacy primarily revolves around gestational carriers, also referred to as gestational surrogates. Unlike traditional surrogacy, where the surrogate’s own eggs are used, gestational carriers are not genetically related to the child they carry.
Instead, the intended parents undergo in vitro fertilization (IVF), where the eggs and sperm are combined in a laboratory to create embryos. These embryos are then transferred into the uterus of the gestational carrier, who provides a nurturing environment for the embryo to develop and grow throughout pregnancy.
While the intended parents start the journey through in vitro fertilization (IVF), it is essential to recognize that gestational carriers themselves are IVF patients too. This process involves intricate medical procedures, making the gestational carrier a vital participant in the IVF journey. Basically the intended parents start the IVF process, and the surrogate finishes it with a pregnancy and delivery.
What’s the big deal with hCG results in IVF?
For anyone who has planned and tried to get pregnant before, you know that moment when a pregnancy is confirmed is a big deal. Well, the hCG results are the magic numbers that confirm whether the embryo transfer was a success and the surrogate is pregnant (or not likely pregnant).
hCG (human chorionic gonadotropin) results in IVF are of significant importance and closely monitored throughout the IVF process. hCG is a hormone produced by the placenta after embryo implantation, and its presence in the bloodstream is a crucial indicator of pregnancy.
That very long “2 week wait” / 10 days after embryo transfer.
Some of the most difficult components of the IVF process are the long stretches of time that one must wait to receive important results. A particularly difficult wait is known as the two week wait (which really isn’t two weeks, but it gets its name from the two week wait between ovulation and a missed period). This wait lasts from the day that an embryo transfer occurs until the result of a pregnancy test is revealed.
What happens in the uterus after an embryo transfer?
When embryo implantation initially occurs (roughly 24-48 hours after a blastocyst embryo transfer, though some embryos exhibit slightly delayed implantation), the embryo’s placental cells begin to burrow into the uterine lining (endometrium). As the placenta develops in the uterine lining, its cells produce increasing amounts of the hormone hCG (human chorionic gonadotropin). Thus, the presence of hCG indicates that embryo implantation has occurred.
How is hCG detected?
hCG can be detected in urine (a qualitative test) or blood (a quantitative test). Most IVF clinics schedule a quantitative blood test 9-12 days after an embryo transfer occurs. This blood test, which is known as a beta hCG, measures the level of hCG in the blood. This blood sample is obtained through a simple blood draw (it’s just like having your other hormone levels checked). In many cases, the result is available on the same day that the blood sample is drawn.
Keep in mind that a qualitative (urine) pregnancy test requires a large amount of hCG to be present in the urine in order to show a positive result, and a positive result may not be observed until after a blood test has been performed.
What do my initial hCG levels indicate?
The result of a beta hCG blood test is often given in units of mIU/ml (though some countries use pmol/L).
Generally, initial results can be categorized as follows:
- A result of <5 mIU/ml is considered negative and implies that embryo implantation did not occur.
- A result of ≥25 mIU/ml is considered positive and implies that embryo implantation did occur.
- Results between 5 and 25 mIU/ml can be concerning, though healthy live births can result from these initial levels if they continue to rise appropriately. At times, low initial results can indicate an ectopic pregnancy, miscarriage, or blighted ovum.
What happens if my hCG is negative (<5 mIU/ml)?
A repeat blood test can be performed, but it is not required. In these situations, a woman should get her period 10-12 days after the transfer occurred. A failed embryo transfer does not mean that a future transfer cannot be successful. Talk with your doctor about your next steps and possible options moving forward.
In some situations, certain fertility medications that contain a synthetic form of hCG are administered before an embryo transfer. It can take some time for the synthetic hCG to exit the bloodstream, so very small levels may be detectable on a very early pregnancy test. These levels should never exceed 5 mIU/ml, though.
My initial hCG is ≥5 mIU/ml. Now what?
An initial hCG level that is ≥5 mIU/ml is just that: one result. It is very important that hCG levels continue to rise appropriately (nearly doubling every 2-3 days) to ensure that development is occurring properly. Therefore, multiple beta hCG blood tests are typically scheduled every 2-3 days to ensure that the levels are rising appropriately. If the hCG levels are not rising appropriately or are declining, it could indicate that a chemical pregnancy (a pregnancy that ends before it is detectable on an ultrasound) or ectopic pregnancy has occurred.
What are normal hCG levels as a pregnancy progresses?
Each clinic or lab may have its own reference ranges, but the American Pregnancy Association uses the following ranges to determine normal hCG levels at each week of a pregnancy.
Normal beta hCG levels (mIU/ml) in weeks since last menstrual period:
- 4 weeks (usually ~9 days after transfer) should be between 5 – 426.
- 5 weeks (~16 days after transfer) should be between 18 – 7,340.
- 6 weeks (~23 days after transfer) should be between 1,080 – 56,500.
What happens if my hCG levels rise appropriately?
An ultrasound is normally scheduled once the hCG levels reach 1,000-2,000 mIU/ml, though this may differ between IVF clinics. Though most clinics do not continue to measure hCG levels once an ultrasound has been performed, these levels should continue to rise until the end of the first trimester, at which point they will begin to naturally decline.
What to know about hCG levels and ectopic pregnancies.
High hCG levels early on in pregnancy can be an indication of an ectopic pregnancy.
An ectopic pregnancy occurs when the fertilized egg implants outside of the uterus, most commonly in the fallopian tube. In these cases, hCG levels may rise at a faster rate than expected for a normally progressing pregnancy. While the exact threshold for what is considered “too high” can vary, significantly elevated hCG levels in early pregnancy can raise suspicion of an ectopic pregnancy.
It’s important to note that high hCG levels alone are not definitive proof of an ectopic pregnancy. Further diagnostic tests, such as ultrasound examinations, are typically conducted to confirm the location of the gestational sac and evaluate the overall health of the pregnancy.
If an ectopic pregnancy is diagnosed, it is a serious medical condition that requires prompt intervention. Ectopic pregnancies cannot proceed to full term and can pose significant risks to the woman’s health, including the potential for fallopian tube rupture. Treatment options for ectopic pregnancies may include medication to dissolve the pregnancy or surgical intervention to remove the ectopic pregnancy.
Monitoring hCG levels and conducting additional diagnostic tests are crucial in identifying and managing ectopic pregnancies. Early detection and appropriate medical intervention are essential to protect the health and well-being of the woman involved.
A note about home pregnancy tests while waiting for hCG beta results.
It can be very tempting to test for a pregnancy earlier than is advised by a fertility specialist. This is completely understandable and, in many cases, pregnancies can be detected on a home pregnancy test before a beta hCG blood test is scheduled. However, home pregnancy tests do not show positive results until the hCG levels in the urine are quite high. With that being said, home pregnancy tests can show false negatives (you are pregnant but there is not enough hCG in the blood for the home test to detect it). This can cause a lot of unnecessary stress and is why many IVF clinics wait until 9-11 days after an embryo transfer to perform an accurate, quantitative blood test. Please never assume that you are not pregnant without a doctor’s confirmation.Learn More