Contact Vicki
If you have any questions or would just like more information please don't hesitate to get in touch by clicking the button below and filling out the contact form.
Contact Vicki
So, you have just been for your 20-week scan and your sonographer has told you that you have a low-lying placenta, and you will be monitored to see if you can birth vaginally, or you may have even been told to prepare for a caesarean.
It is important NOT TO STRESS!
A low-lying placenta can be common in early pregnancy and should not be confused with “placenta praevia”.
The most common types of placenta praevia are:
The main concern is if your placenta is covering the cervix either fully or partially towards the latter stages of pregnancy, then this is known as placenta praevia.
This happens in about 1 in 200 pregnancies and can cause major blood loss in the mother; therefore, babies are born by caesarean. A woman who has a fully covered cervix in early pregnancy is most likely to stay that way and will be required to have a caesarean.
I’m only going to be focussing on a “low lying placenta” in this article and how the changes occurring between your 20-week scan and your birth can make a huge difference in where your placenta is positioned.
To the frustration of many childbirth educators, midwives and doulas we wish you would get told this next bit of information from the start of learning you have a “low lying placenta” so that you are not stressing about it.
Placental migration refers to the natural movement or shift in the position of the placenta within the uterus as pregnancy progresses. It’s a normal and common phenomenon — especially relevant when a placenta is identified as low-lying early in pregnancy.
Despite the term “migration,” the placenta doesn’t actually move like a separate object. Instead, it’s attached to the uterine wall. What happens is:
As the uterus grows and stretches upward, especially in the second and third trimesters, the lower uterine segment expands and pulls the placental attachment point upward with it.
This can make a previously low-lying placenta move away from the cervix, even if it appeared close or overlapping early on.
A low-lying placenta (or placenta praevia) diagnosed on a scan in early or mid-pregnancy can cause concern, but in most cases, it resolves on its own due to placental migration.
If a low-lying placenta is found at the 20-week scan, around 90–95% of cases will “migrate” upwards by the third trimester.
True placenta praevia (covering the cervix) persisting into late pregnancy is relatively rare.
Early detection of a low-lying placenta doesn’t mean a woman will definitely need a caesarean.
Follow-up scans (usually around 32–36 weeks) are done to reassess placental position.
If the placenta remains within 2cm of the cervix at term, especially if covering, a caesarean may be recommended to prevent complications like bleeding during labour.
A caesarean may be recommended if the placenta is still close to or covering the cervix later in pregnancy because of the risk of serious bleeding (haemorrhage) during labour and birth. Here’s a breakdown of why:
If the placenta partially or completely covers the cervix (the opening of the uterus), it physically blocks the birth canal. In this case, vaginal birth is not possible, and a caesarean is essential for a safe delivery.
Even if the placenta is just very close to the cervix (within 2cm), it can start to detach as the cervix softens, thins, and opens in labour. This can cause significant bleeding, which puts both mother and baby at risk.
Bleeding may:
Be unpredictable and heavy (called antepartum haemorrhage),
Require emergency intervention,
Lead to preterm birth or urgent caesarean.
A planned caesarean before labour starts can help:
Avoid an emergency situation if bleeding begins during labour,
Reduce stress and risk for both mother and baby,
Allow doctors to prepare in a controlled setting with appropriate staff and equipment.
Ultrasound assessment is used to measure how far the placenta is from the internal os (cervical opening). Guidelines vary slightly, but generally:
If the placenta is more than 2cm from the cervix – vaginal birth may be possible.
If the placenta is less than 2cm away or overlapping – caesarean is usually recommended.
DEMONSTRATION
So, to demonstrate this marvellous “movement” of your uterus and therefore your placenta, grab yourself a balloon.
Put a black blob which will represent your placenta at the base of the neck of the balloon and then blow up the balloon.
As you blow and the balloon expands (think of this as your uterus), so too you can see how the black blob (your placenta) moves away from the opening at the neck of your balloon (your cervix) – the same way as your uterus expands and stretches, so too your placenta is carried up and away from the cervix opening.
Here is a video to demonstrate for you:
Now is the time to enjoy your pregnancy and start exploring independent childbirth education classes. These classes can help you feel well-informed, prepared, and confident as you plan for your labour and birth.
REFERENCES
http://www.webmd.com/baby/understanding-placenta-previa-basics
http://www.babycenter.com/0_placenta-previa_830.bc
http://www.webmd.com/baby/understanding-placenta-previa-basics
http://www.healthline.com/health/placenta-previa#Diagnosis4
If you have any questions or would just like more information please don't hesitate to get in touch by clicking the button below and filling out the contact form.
Contact Vicki