“Mailbag #17: What does the Fox say?” Nicole’s Question

Nicole’s Question

“Hello. First, I want to say I love your podcast and truly appreciate all the helpful knowledge you share. I recently found out I’m pregnant, but experienced bleeding roughly a day later. My doctor had me take blood tests two days apart to determine HCG and progesterone levels. I’m curious why my HCG would be going up, but my progesterone is extremely low. What might they recommend, or am I having a chemical? Thanks.”

Dr. Fox’s Answer

Okay. So, as some background, when someone gets pregnant and they take a pregnancy test, whether it’s a urine test or a blood test, the thing that is being tested for is something called HCG, which stands for human chorionic gonadotropin. Essentially, it is a hormone that is secreted during pregnancy inside the uterus. And so if it’s positive, that is what we use to determine that someone is pregnant.

HCG is also frequently used by people to gauge whether a pregnancy is a healthy pregnancy or an unhealthy pregnancy. Typically, that would be done in the time period before the pregnancy is properly seen on ultrasound. So, when someone gets pregnant, you conceive, and about two weeks later, give or take, you miss your period, and that’s around the time a pregnancy test would first become positive. But if you went and got an ultrasound at that time, we would call that four weeks, or two weeks from conception. You wouldn’t really see anything on an ultrasound, probably for at least another week. And even then, when you start seeing something on ultrasound, it’s this little empty sack, and then it grows, and you’re not going to see an embryo with a heartbeat until around six-ish weeks, which is four weeks from conception. So, in that time period before seeing a heartbeat, people want to know, is this pregnancy a healthy pregnancy? Something that’s called a viable pregnancy, or is it not? And so, one of the ways that’s sometimes done is by testing HCG levels serially because in a healthy pregnancy, the HCG, at least in the beginning part of pregnancy, basically goes up and up and up and up and up.

Now, people have said the HCG should double every two days.

That’s not exactly right, but it should be going up pretty steadily and impressively over the beginning part of pregnancy. So, for example, if someone has a positive pregnancy test, on a urine stick at home. They come into the doctor’s office or go to the lab, and they get an HCG, and it’s 400. That itself doesn’t usually tell you that much. You can’t see anything on an ultrasound. It confirms that someone is pregnant, but it doesn’t tell you if the pregnancy is viable. Technically, it doesn’t even tell you that it’s in the uterus because an ectopic pregnancy can have this as well. And then sometimes it’s recommended, “All right, go back and get your blood tested again two or three days later.” And in two or three days, if it, let’s say, still measures 400 or worse, it measures lower, probably this is not a viable pregnancy, and either it means you’re miscarrying or in rare circumstances, it could be an ectopic.” However, 2 to 3 days pass, and instead of 400, it’s now 800, 1,200, 1,500, or something like that. It doesn’t guarantee that it’s a normal pregnancy, but it certainly points in that direction, and then generally you’ll wait and do an ultrasound sometime thereafter. So, that’s one hormone that’s used to track pregnancies frequently. Traditionally, there’s a lot out there on that.

Now, it’s not done for everybody routinely. It’s done very frequently by fertility centers because they’re trying to track this very closely. It’s done sometimes for people who are concerned they might have an ectopic pregnancy. It’s done for people who maybe they don’t know if they have a viable pregnancy, and they have some symptoms, and they’re coming in, but it’s not something that I do in every person who calls and says, “I’m pregnant.” Usually, it’s not done, but it could be done.

Now, progesterone is a pregnancy hormone, but it’s a little bit different. In pregnancy, it’s not used in terms of serial levels to make sure it’s going up versus going down, like we do at HCG. Early in pregnancy, when someone gets pregnant, the source of progesterone is the corpus luteum in the ovary, which is where the egg came out from. And that corpus luteum secretes progesterone. And if someone doesn’t get pregnant, it secretes progesterone for a certain amount of time, and then it stops, and the corpus luteum sort of goes away, and you go on to your next cycle.

But if you are pregnant, the HCG that’s secreted by that pregnancy then keeps that corpus luteum alive, so to speak, and the progesterone does not drop, and it sort of stays elevated. So, people sometimes will use progesterone levels to determine if this is a healthy pregnancy or not. And certain levels of it are very low, which might indicate a non-viable pregnancy. And if it’s above a certain level, it might indicate a more viable pregnancy. And the data in this is a little bit more mixed, and how to sort of use it in conjunction with the HCG. People do it a little bit differently. One of the things is that if there’s a low progesterone, sometimes people will say, “All right, we’ll give you extra progesterone.” And then others will argue, “Well, that doesn’t work because the reason the progesterone is low is because the pregnancy is bad, not because the corpus luteum is bad.” And that’s sort of an ongoing debate, I would say. Most people believe that giving supplemental progesterone is not valuable, and there doesn’t seem to be any data to support that it improves the pregnancy. But some people do it, and that’s fine. It’s not dangerous to take extra progesterone. 

So, in terms of your question, why would your HCG be going up and your progesterone extremely low? Well, it could be several things.

It could be that this is a normal, healthy, viable pregnancy. And just for whatever reason, your progesterone is low. That’s one possibility. The other possibility is that it is, in fact, not a viable pregnancy. And definitely, there are non-viable pregnancies that have HCG that go up until a certain point, and then it might peak. And so ultimately, the key is that in this situation, you might not know if it’s a viable pregnancy until a week or two, when you could see an ultrasound and see if there’s a heartbeat and whatnot. But that situation is not so uncommon. 

Maternal Fetal Medicine blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!