Congrats! You’re pregnant! In between reading up on what fruit the baby is the same size as and riding a roller coaster of emotions and nausea, you’re likely also getting comfortable with terms you don’t use much in everyday conversation. You know the baby’s growing in your uterus, but is that in front of or behind your stomach and your bladder? You know your cervix will dilate, but how wide is 10 centimeters really (and why don’t we just use inches?)? You’ve heard of the placenta, and know it’s the baby’s oxygen and fluid and nutritional lifeline, but where is it exactly, and to what does it attach?
When you have your anatomy scan around 20 weeks gestation, you might hear placenta with some other words, words you’ve never heard of. Low-lying placenta, placenta previa, placenta accreta, or even placenta percreta. Suddenly, you might feel very worried. But should you be? I’ll cover the highlights of each one of these placenta issues so you know when and when not to worry. Oh, and there’s one other placenta issue that can happen suddenly and without warning, called placental abruption. Because it’s a very serious placental problem and you should know the warning signs, I’ll cover that too.
Please note: I’m not attempting to be comprehensive here. I’m sharing a high-level overview of the most common placental problems so you can gain a basic understanding that hopefully helps you take a deep breath and then enables you to go and ask questions of your healthcare team if necessary.
What exactly is the placenta and what’s normal for placental attachment?
After conception, your baby grows rapidly through several stages of development, from zygote to blastocyst to embryo. The embryo implants 5-7 days after conception, into the uterine wall. After implantation, the placenta develops to support your baby nutritionally and also to remove waste products from his or her blood. Normally, the placenta attaches high up in the uterus and towards the front. It should attach to the lining of the uterine wall, also known as the endometrium. The placenta should remain securely attached to your uterus throughout your pregnancy, and it will grow as the baby grows. While the location of the placenta does not per se change during your pregnancy, due to your expanding uterus the placenta may appear to ‘move’. During the last stage of labor and after you give birth, in what’s called the afterbirth, the placenta should detach from the uterus and slide out (with a few small pushes).
Low-lying placenta
I learned that I had a low-lying placenta during my last pregnancy, meaning that the placenta was attached to the uterine lining close (2cm or less) to the opening of my cervix. I first heard about it during my 20 week anatomy scan. I was told very little by my healthcare team at that time, so I turned to Dr. Google, who informed me that the overwhelming majority of cases of low-lying placenta resolve on their own as the pregnancy progresses.
For those cases that don’t resolve, and remain less than an inch from the cervical opening as the pregnancy progresses, there’s a risk of hemorrhaging (excessive bleeding) during labor as the cervix dilates more and more. My placenta remained resolutely in place through several scans. I read more, and learned that a Cesarean section is an option if the placenta stays too close, but then I also read that hemorrhage is a possibility with a Cesarean section, too! My provider told me that I could always try a “trial of labor,” meaning that I’d go into labor spontaneously and then we’d see how I tolerated it. A C-section would be quickly accessible if I needed it.
I had one last scan at 36 weeks, and my regular provider wasn’t there to read the results. The other provider who came in brusquely told me there was no way to see how close my placenta was to the cervix because my baby was head down and right on top of it. I was shocked, dismayed, and angry at having had a scan that apparently told us…nothing. I was equally surprised when at my 37 week prenatal appointment, my regular provider cheerily informed me that, based on her review of the exact same scan, my placenta had moved the tiniest fraction and was now more than 2cm away from the cervix!
Bottom line: Your low-lying placenta will most likely resolve on its own. “Wait and see” is the operative phrase here. If your placenta remains very close to the cervix, you still have the option of trialing labor, with the understanding that a C-section may be necessary if you begin bleeding too heavily. Low-lying placenta is the least serious form of placental problem.
Placenta previa
Placenta previa occurs when your placenta grows partially or completely over your cervix– think literally on top of it. You can’t birth a baby vaginally with a placenta previa because your placenta is physically in the way and could cause hemorrhaging. As with low-lying placenta, your provider could identify placenta previa during a second-trimester or later ultrasound. Or, you might find out you have it because you experience sudden, bright red, painless vaginal bleeding during or beyond week 20 of pregnancy. If you do experience unexplained bleeding, call your doctor right away to get it checked out. They may tell you to go to the hospital. If you lose a lot of blood, you might need a blood transfusion.
What’s the treatment for placenta previa? You’ll have more frequent ultrasounds than you would otherwise. As with a low-lying placenta, placenta previa often resolves on its own, moving out of the way as the uterus grows over the course of the pregnancy. If you have severe bleeding, your team will determine whether the baby needs to come out right away, which would mean an urgent (needs to happen very soon) or emergent (needs to happen now) C-section.
According to the Mayo Clinic, if you’ve had just one episode of bleeding and it stops on its own, you may get to go home after being monitored in the hospital for 48 hours or so. If you learn you have a previa but do not experience bleeding, you’ll be closely monitored until around 36-37 weeks, and encouraged to avoid sex as well as strenuous exercise or activity. Around 36-37 weeks, you’ll have a scheduled Cesarean section.
Bottom line: Placenta previa bleeding is usually painless. This distinguishes it from painful placental abruption bleeding (more on this below). Unlike with low-lying placenta, a placenta previa that does not resolve on its own doesn’t leave you an option for trialing labor. For your safety and your baby’s, he or she will be born on a set date via C-section. Questions to ask your doctor, and questions they should ask you, are here.
Placenta accreta, increta, and percreta
If you’ve had one or more previous Cesarean sections or other surgeries involving your uterus, in rare cases the old surgical scars may lead to problems with the placenta called accreta, increta, or percreta. Moms who have certain congenital uterine abnormalities are also at risk. In every case of accreta, increta, or percreta, the placenta attaches too deeply in the uterus. It doesn’t just attach to the lining, but deeper into the muscle. The question is ‘how deep?’ The least invasive form of abnormally deep attachment is accreta, which is often accompanied by placenta previa. Increta refers to placental attachment deeper into the uterine muscle wall. Percreta is the severest form, and means that the placenta is attached all the way through the muscle and is bulging up against or even connected to the bladder.
All of these conditions can lead to hemorrhaging for mom, especially if she delivers vaginally and the accreta, increta, or percreta isn’t diagnosed ahead of time. Placenta accreta, increta, or percreta might be suspected if you experience bleeding without reason during your third trimester, though accreta in particular often doesn’t have warning signs. All are diagnosed through ultrasound and may need MRI confirmation. If one of these conditions is identified ahead of time, you and your provider will discuss a planned C-section, perhaps before you’re full term. You may try to labor for a vaginal birth, and then the plan may very suddenly change to keep you safe. A hysterectomy after C-section is a possibility if bleeding gets out of control.
Bottom line: A diagnosis of placenta accreta, increta, or percreta, while very rare, is worth paying close attention to. These placental problems can be very dangerous for mom and, by extension, for baby. Really great resources, including brief videos, to help you feel more calm and educated about these conditions are here.
Placental abruption
While placenta accreta, increta, or percreta can become life-threatening, rapid-onset placental abruption is always, 100% of the time, an emergency. Placental abruption is the premature, partial, or complete separation of the placenta from the uterine lining before birth. It’s most likely to happen in the last trimester, even just weeks before full-term. It’s a life-threatening, all-hands-on-deck emergency for a baby, because he or she gets partially or completely separated from the nutrition + oxygen + fluid lifeline, and for mom because of hemorrhaging and shock from blood loss, which could lead to kidney failure, and/or blood clotting issues.
I still remember hearing in nursing school that you should suspect placental abruption if a pregnant woman comes in complaining of sudden severe pain, heavy bleeding, and whose abdomen is “stiff as a board” on one side in particular. Uterine tenderness, cramping, and backache are also possible. It’s even possible to have an abruption without obvious external bleeding, depending on the location of the bleed.
You treat an abruption by getting the baby out immediately via C-section. A blood transfusion or multiple transfusions may be necessary for mom.
Bottom line: You likely wouldn’t know you had placental abruption ahead of time, though occasionally abruption, called chronic abruption, will happen very slowly. Generally, though, you’d be unaware in advance. Know the symptoms. Sudden heavy bleeding accompanied by pain means go, go, go to the emergency room. You can call your doctor along the way, but go straight to the hospital. Placental abruption is the most serious kind of placental problem.
Can other placental problems occur?
Yes, there are other things that can happen with your placenta that I don’t cover in this article, but are touched on here, at the end. I’ve just covered the “most common” issues, even though I want to stress that they are all uncommon, relatively speaking.
So, should I be worried if I have a placental problem?
Honestly, no. Being worried or so anxious that you’re unable to think clearly, or can’t turn your mind toward other things outside of your prenatal appointments, won’t be helpful no matter which of these conditions you have–and it certainly won’t be helpful if you are pregnant and have not yet been diagnosed with any of them! And again, these conditions can be serious, but they are also still relatively rare. Don’t let worry steal your joy from the gift of having a new life growing inside of you.
In other words, you never need to worry. But should you be concerned if you have placenta previa or placenta accreta or increta or percreta? Yes, you should absolutely pay attention to your body and any symptoms you may have, ask lots of questions, and be sure you’re in the hands of a healthcare team who is experienced in dealing with these types of issues, and has the confidence and tools in place to keep you and your baby safe. You should feel secure in their capable care. If you don’t, make no apologies, waste no time, and find another provider. You and your baby deserve the best care you can get, no matter if it’s an easy pregnancy, or one with complications.
Additional Reading:
Cervical checks during pregnancy: What they can—and can’t—tell you
