What is hCG and when does the embryo start producing it?
hCG, human chorionic gonadotropin, is the pregnancy hormone. It is made by the cells that will become the placenta, the trophectoderm of the embryo, once the embryo has attached to the uterine wall. hCG signals the body to keep supporting the pregnancy. It is also what every pregnancy test, blood or urine, detects.
A "beta" is short for beta hCG, the blood test that measures the hormone's level. The result is reported as a number in mIU/mL, milli-international units per milliliter. Unlike a home test, which only says yes or no, the beta gives a number, and a second beta shows whether that number is rising as it should.
An embryo cannot make hCG until it implants. A day 5 blastocyst typically implants in the first few days after transfer, and hCG then enters the surrogate's blood in small amounts that rise quickly in early pregnancy.
When is the first beta drawn, and why not earlier?
The first beta is drawn 9 to 11 days after a day 5 blastocyst transfer. The exact day is set by your clinic.
Earlier is not better. Before about that point, hCG may be too low to measure reliably even in a pregnancy that is going well. An early negative can be false, and an early low positive can cause worry that a few more days would have resolved. Waiting gives a number that means something.
The draw is usually done at a lab or clinic near the surrogate's home, and the result goes to your fertility clinic. The frozen embryo transfer protocol page shows where the beta sits in the full calendar.
What first beta values do clinics consider reassuring?
Every clinic sets its own thresholds. A value above 5 mIU/mL is generally considered positive. Many clinics consider a first beta above 50 to 100 mIU/mL reassuring after a day 5 transfer.
Two points keep the first number in perspective.
First, normal values vary widely. Two healthy pregnancies can have first betas several times apart. A lower first number is not a diagnosis.
Second, the trend matters more than any single number. That is why clinics repeat the test.
| Days after a day 5 transfer | Typical range | Interpretation | Next step |
|---|---|---|---|
| 9 to 11 (first beta) | Set by your clinic. Above 5 mIU/mL is positive; 50 to 100 mIU/mL or more is commonly considered reassuring. | Positive, negative or low positive | Repeat beta, or stop medications if negative and the clinic confirms |
| Repeat beta, timed by your clinic | Set by your clinic. Roughly double the first value; a rise of at least 50 to 60 percent is usually acceptable. | Rising as expected, slow rise, or falling | Further betas if unclear; otherwise schedule the first ultrasound |
| Further repeats, if ordered | Set by your clinic | Confirms the trend | First ultrasound when the clinic decides |
Doubling-time guidance: in early pregnancy, hCG commonly doubles about every 48 hours. A slower rise is not always a problem, and clinics often accept a rise of at least 50 to 60 percent over 48 hours.
The figures in this table are pending review by Dr. Silverberg, who will set the published values.
What should the second beta show?
The second beta checks the direction. Most clinics repeat it 48 hours after the first, and look for the number to roughly double, with a rise of at least 50 to 60 percent usually considered acceptable.
A rising number is the main sign that the pregnancy is developing. A first beta that was "low" but rises well on the repeat is often a healthy pregnancy. That is why a low first number should lead to a repeat, not a conclusion.
Some clinics order a third beta when the pattern is unclear, then move on to the first ultrasound.
What does a slow rise or a drop mean?
A slow rise means the number is going up but more slowly than expected. It can mean an early loss is coming, an ectopic pregnancy (one implanted outside the uterus, usually in a fallopian tube), or simply a pregnancy that started a little later. The clinic will repeat the test and may order an earlier ultrasound.
A drop usually means the pregnancy has stopped developing. When hCG rose briefly and then fell, it is often called a chemical or biochemical pregnancy: the embryo implanted but did not continue. It is common in IVF and in natural conception, and it is still a loss for everyone involved.
A very high number can suggest twins. Even with a single embryo transferred, an embryo occasionally splits into identical twins.
Call the clinic or seek urgent care for one-sided abdominal pain, shoulder pain, heavy bleeding, dizziness or fainting. These can be signs of an ectopic pregnancy, which needs prompt treatment.
Can a home pregnancy test be trusted before the beta?
Not reliably. Home tests detect hCG in urine and need a higher level than a blood test to show positive. A home test can be negative in a pregnancy that is going well, or faintly positive and leave you guessing. Many clinics ask surrogates not to test at home, or at least to wait for the beta before acting on a result.
A false positive from medication is not a concern for a surrogate in a medicated frozen embryo transfer. A trigger shot of hCG can cause a false positive, but only in fresh cycles where the egg provider received it. The surrogate receives no hCG, so a positive result reflects a real pregnancy.
What happens after a positive beta: medications, ultrasound, release to OB
After a positive beta, nothing changes in the medications. The surrogate continues estrogen and progesterone exactly as prescribed. In a medicated cycle, her body depends on them until the placenta takes over. Clinics usually stop progesterone around 10 weeks of pregnancy, and the clinic sets the taper. See the progesterone in oil page.
Next comes the first ultrasound, which confirms a gestational sac in the uterus and usually a heartbeat. The fertility clinic performs early ultrasounds and then releases the surrogate to her own obstetrician. The schedule and what each scan shows are on the early ultrasounds and release to OB page.
How does PLS handle sharing results with the surrogate and parents?
PLS shares results with the intended parents and the surrogate at the same time. Neither side hears the news secondhand.
That matters for both sides. The surrogate has carried the medications and the waiting. The parents have carried the hope and the cost. A positive beta, a low number or a negative result lands differently for each, and both deserve to hear it directly. Case managers Natalie Gaudio-Fricano and Jenni Symons, who carry the active matches, have both been surrogates and have waited for a beta themselves.
If a result is negative or a pregnancy is lost, mental-health support is part of what PLS provides surrogates, and the next step is planned with your clinic. The pregnancy test comes 9 to 11 days after transfer in a journey that typically runs 18 to 24 months. See how long surrogacy takes.
This page gives general information. It is not medical advice. Your clinic interprets your numbers and decides the next step.
Sources
- ASRM (American Society for Reproductive Medicine), patient information on early pregnancy after IVF. https://www.asrm.org/
- ACOG (American College of Obstetricians and Gynecologists), guidance on ectopic pregnancy and early pregnancy loss. https://www.acog.org/
- SART (Society for Assisted Reproductive Technology), patient information on IVF. https://www.sart.org/