Not surprisingly, I've spent a lot of time researching it. Chances are good, though, that you know little to nothing about it, unless it's an issue that affects you personally as well. Even if it does affect you, you still might not know much. That's not your fault. All of my pregnancy books--and I have a lot of them--gloss over it. Four or five sentences max. All of which can be summed up with "get the RhoGAM and you'll be fine."
The thing is, that's not true. Not for everyone.
Not for me.
Rh Incompatibility: the Basics
Let's back up a bit. What is Rh incompatibility? The Rh (rhesus) factor is essentially an antigen (a type of protein) that occurs on the blood cells of most people. Eighty-five percent of people have this protein, and are thus considered Rh positive. The rest of us (like me) lack this protein, and are considered Rh negative.For the most part, for most of your life, this is a pretty inconsequential fact. Sure, if you ever need to receive blood, it'll come up, but it's really not a big deal. When it IS a big deal is during pregnancy. Specifically, it's a big deal if the mother has Rh(-) blood and the father has Rh(+) blood. That is what's known as Rh incompatibility. Any baby created in a union like this has at least a 50% chance of also having Rh(+) blood. And that's where the problem lies.
You see, if some of that baby's Rh(+) blood mixes with mom's Rh(-) blood, then it will spark an immune reaction. Mom's blood sees that extra little protein as a threat, and will create antibodies against it. If this happens, it's called becoming Rh sensitized, or isoimmunized.
Now, this is generally not an issue during a first pregnancy. Most of the time, blood mixing will not happen during a first pregnancy. Sometimes, it may happen randomly during the third trimester, but not always, and when it does happen, there's no real way of predicting it. Chances are good, however, that blood mixing will happen at birth. (And contrary to what others might tell you, it'll probably happen no matter how peaceful and gentle the birth is. It just happens. You can't really prevent it.)
Blood mixing is also a possibility during certain types of prenatal testing (such as amniocentesis), or if the mother suffers some sort of abdominal trauma (think a really bad fall, or a car accident). But even if blood mixing does happen, chances are good that her immune response won't be bad enough to endanger the baby during a first pregnancy.
Subsequent pregnancies, though. That's where things get tricky. If mom is isoimmunized and gets pregnant with another Rh(+) baby, then her immune system will see that baby as a threat. Her immune system will ramp up production of those particular antibodies and go on the attack. This can be bad news for the baby, and can even result in the baby's death if the situation is not monitored and treated appropriately.
RhoGAM: the Solution?
Fortunately, there is a way to prevent Rh sensitization. It's a drug commonly known as RhoGAM, and women who are at risk are advised to get a dose of it at around 28 weeks and again within 72 hours of delivery. Women are also supposed to receive it if there is any other possibility of blood mixing--one of the scenarios mentioned above, or if the woman has an abortion or a miscarriage.Here's what RhoGAM is: purified anti-D antibodies of the sort that the woman's immune system would otherwise produce on its own. Here's what it does: it goes through and essentially cleans up the woman's blood for her. These purified antibodies attack and get rid of the foreign Rh(+) blood before her immune system has a chance to create antibodies of its own. RhoGAM is not a vaccine (although many people erroneously refer to it as a blood-based vaccine), and it doesn't provide long-term protection. Most studies indicate that it is rather effective if it's given within 72 hours or so of blood becoming mixed; some studies say it's effective if given within ten days. But it doesn't stay in your system long-term, which is why it's advised for every at-risk pregnancy; it doesn't matter if you've received RhoGAM in the past.
Like any medication, it's not 100% effective, and furthermore a lot of people wonder about the effectiveness (and necessity) of the 28-week injection, with no proof of definite blood mixing. But that's another issue. The fact of the matter here is that, given appropriately, RhoGAM is generally quite effective, the additional ingredients are relatively benign (sodium chloride, Polysorbate 80, glycine; trace amount of IgA; no HSA, no thimerosal, no other preservatives), and reported reaction rates are relatively low (take that with a grain of salt, of course).
My Background
I did not receive RhoGAM during my first pregnancy, although I did have a dose of it within 72 hours of giving birth, at the advice of my midwife and at the recommendation of my own research.After my first miscarriage, I learned that I was Rh sensitized.
But wait, I had the RhoGAM! Well, the way I see it, there are three possibilities for what happened:
~It didn't work for me. That would make me part of the reported 0.1-0.2% for whom RhoGAM is ineffective.
~I didn't receive enough of it. RhoGAM is dosed based on an estimate of how much blood mixing happened, and it's possible that they just didn't give me enough of it. With too low of a dose, my body would have had the immune reaction anyway.
~Isoimmunization happened as a result of my miscarriage; after all, I did spot-bleed for more than three days before going into the hospital, and I was there bleeding everywhere for eight hours before anyone thought to give me RhoGAM (and I obviously wasn't in the right state of mind to ask for it).
Anyway, the fact of the matter is that I am indeed Rh sensitized. I've had it confirmed three times since my miscarriage, and while my titer (antibody) levels are low, my body does still maintain them, and has the ability to make more if it feels threatened again.
Like it just might with this new baby.
So after my current care provider once again confirmed my status as Rh sensitized, they sent me to consult with someone from the high risk group. Yes, that's right; after my perfect, easy, low-risk first pregnancy/birth and then two miscarriages, I'm now officially high risk, which means I'm pretty much stuck with a hospital birth. Not my ideal, but it's the smart (and only) option here.
The real question is, what exactly does that mean for this pregnancy?
The Plan
The ideal first step is to find out my actual risk level. Remember how I said earlier that a baby produced by an Rh(-) mother and an Rh(+) father has at least a 50% chance of also being Rh(+)? That means that, potentially, it could have a 50% chance of being Rh(-), in which case all of this is moot. I can go back to being low-risk, no further monitoring needed.To that end, my doctor wants my husband to have his Rh genotype/phenotype checked. This will determine if he is homozygous for the D antigen (for being Rh[+]), or if he is heterozygous. If he's heterozygeous, then my odds are officially 50/50.
Don't have a clue what that means? Think back to the basic, oversimplified version of human genetics you studied in high school. Remember dominant traits and recessive traits? You can think of this in those terms. Having the D antigen means you are Rh(+); this is the dominant allele. Homozygeous would mean he has two dominant alleles for the D antigen. Heterozygous would mean he has one dominant and one recessive. I have Rh(-) blood; I have two recessive alleles. If my husband is heterozygeous, the baby would definitely receive one recessive from me, but it's 50/50 as to whether it'd receive a dominant or a recessive from my husband; thus, there is a 50% chance of the baby being Rh(+), and a 50% chance of it being Rh(-).
This is a simple blood test that is easily done, and should definitely be covered by insurance. If we find out that he is heterozygeous, then we get into slightly more advanced testing. The next step would be to determine the Rh genotype/phenotype of my unborn baby's blood. This can be accomplished through a test called the cell free fetal DNA (cffDNA) test. It's a completely low-risk, non-invasive test; it finds free-floating fetal DNA in my, the mother's, blood, and uses that to determine whether the baby is Rh(+) or Rh(-).
Unfortunately, this test is still considered "experimental" in our country. Health insurance companies usually refuse to cover it, although my doctor is going to write a letter to mine to try to get pre-approval. After all, it's cheaper than the alternative (amniocentesis can also determine the baby's Rh status, but in my opinion, the risks of amnio outweigh the potential benefits here), and it could ultimately save them a lot of money depending on the results. If insurance still won't pay for it, I could pay out-of-pocket; I was told it costs $400, which isn't too bad in the grand scheme of things.
So what happens if the baby is determined to be Rh(+)? Or if we can't tell, because insurance won't pay for cffDNA and I can't afford it?
Blood tests. Lots and lots of blood tests. I anticipate having to get blood drawn at every single prenatal appointment for the duration of this pregnancy. That way, my doctors can monitor my titers (my antibody levels). If they stay low, then it's all good. If they start to go up, and if they go up past a certain threshold, then I'll have to start getting blood work done in between appointments, every two weeks and maybe eventually every week.
If my antibody levels get too high, they'll start monitoring the baby via ultrasound. Interestingly enough, doctors can look at the blood flow between the brain and the rest of the body to see if baby seems to be at risk for what is essentially anemia. In a case of isoimmunization, like I have, it's referred to as hemolytic disease of the fetus/newborn. Remember that my antibodies in this case can pass through the placenta and attack the baby's blood, destroying blood cells. So the ultrasound can help the doctors determine whether or not the baby is suffering as a result of my high antibody levels. Because if it gets too bad, the baby can die from this.
Isoimmunization is definitely not something to take lightly.
And if it is determined that the baby is suffering? Well, that depends on how far along I am in the pregnancy. One option is a procedure called an intrauterine blood transfusion, which is exactly what it sounds like it is: it's giving the baby a blood transfusion while it's still in my uterus. To do this, they'd use ultrasound to monitor the baby's position while sticking a long, thin needle through my abdomen. The goal is to get the needle into the umbilical cord (near the placenta, where it doesn't move as much), and then to give the baby a blood transfusion. This would help offset the effects of my own immune system's ongoing attack.
Unsurprisingly, there comes a time in pregnancy when this procedure is no longer safe (and that's not to imply that it's ever without risks; it's definitely risky, but the alternative--doing nothing--is worse). My doctor describes it as balancing the risks of the procedure with the risks of prematurity: basically, once the baby hits a certain stage of development, it makes more sense to deliver early than to try to attempt an intrauterine blood transfusion.
Induction. Something I dread, but it's a real possibility in this pregnancy.
I was told that, generally, intrauterine blood transfusions are not performed if the baby is past 34 weeks gestation. In some cases, it might not be possible after 32 weeks; that would require a consultation with a different doctor in a different hospital (they don't have that kind of specialist at the hospital I'm going to), who would do yet another ultrasound to examine the baby's size and placement and determine what's best.
So basically, it's possible I might end up with a premature baby here. I acknowledge that reality even as I fervently maintain my optimism that it won't come to that.
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And that's what I'm up against.
To be honest, very little of what the high risk doctor told me at our consultation was actually new information to me. After my first miscarriage, I was devastated and I refused to even entertain the possibility of getting pregnant again for a year and a half. As my grief started to wane (it never has, and never will, go away completely), I began once more to feel the overpowering urge to have another baby. I knew now that I was Rh sensitized, but I didn't fully understand the ramifications of that. And since the Internet is strangely lacking in real information about pregnancy after isoimmunization, I took the initiative and saw a high risk specialist on my own, to find out exactly what an Rh sensitized pregnancy would entail.
I believe in informed consent when it comes to all medical decisions, especially those related to pregnancy, and it seemed irresponsible to jump into a potentially risky situation without knowing any details.
Hopefully, this helps you better understand Rh sensitization, and exactly how it affects pregnancy. It's scary stuff, and I wish that information about it were more readily available. It drives me crazy how much misinformation is out there, getting spread around on blogs and message boards, but hopefully this post can help counter that a little bit.
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What a super helpful and easy to understand article on a sometimes vague and always obscure topic. Thanks for sharing your heart and your learning as always
ReplyDeleteSo very little reliable info out there. I know the science is always changing, but at least now people can get a better idea of the current treatment options!
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