What is an anterior placenta?
The Placenta is the flattish, disk-like organ responsible for delivering to your baby oxygen and all the essential nutrients necessary for his proper growth during the nine months he is inside your womb. It usually grows at the same spot where the fertilized egg implants itself in the uterus, which is usually the posterior uterine wall, the part closest to your spine. However, sometimes the egg may implant in the front (anterior) wall of the uterus, the part closest to your abdomen (as shown in the following diagram). In such cases, the placenta also grows at the front, keeping the baby behind it . This is known as an anterior placenta.
No causes or risk factor have been identified yet, but having a cesarean delivery in a previous pregnancy may make the placenta grow from the site of the old c-section scar .
When and how is an anterior placenta detected?
The position of the placenta is routinely checked during the 20-week anomaly scan . It is after this ultrasound scan that your sonographer writes down the location, categorizing it as anterior, posterior or fundal (placenta attached to the top wall of the uterus) placenta . It may also be embedded in the left or right wall of the uterus in some more rare cases.
Are there any risks to your baby when the placenta lies in front?
All the above mentioned placental positions are completely normal, as it does not affect your baby’s growth in any way . But, it may cause a few problems for you and your doctor if the placenta lies between your baby and your belly.
How is having an anterior placenta different from a posterior placenta?
Feeling the fetal movements may be a bit difficult for you, especially in the late first and early second trimesters, as the placenta creates a cushion between your abdomen and your baby .
Assessing the fetal heartbeat may also be tricky for your doctor or midwife as the Doppler may not work as well through the placenta lying in front . However, it does not usually interfere with an ultrasound or finding out the gender of your baby.
It may also interfere with certain medical procedures like amniocentesis, in case you need one at some stage of your pregnancy . In case your baby is breech or lying in a transverse position, an anterior placenta may make it problematic for your doctor to perform an external cephalic version, also reducing his chances of succeeding .
Are there any signs of an anterior placenta?
There are usually no symptoms to let you know about the location of your placenta before the scan. However, some women report of having back pain that is often more intense than that felt with a posterior placenta.
When do you feel fetal movements with an anterior placenta?
Like in a regular pregnancy, the exact time to feel the first movements of your baby may vary from one woman to another with an anterior placenta. According to many mothers with a placenta lying in front of the uterus, the fetal movements are felt around 22nd–24th weeks. They may become more pronounced with the advancing weeks, allowing you to do regular kick counts and recognize your baby’s sleep-wake patterns.
Possible complications associated with anterior placenta
If you have an anterior placenta, your doctor will be monitoring you with ultrasounds between weeks 32 and 36 to check the exact location of the placenta. You can have a normal labor and natural birth with a placenta lying at the front, as it usually moves upwards in the womb as your baby grows in size, being well out of the way when the time comes for delivery . But, in some cases, it may lead to a few complications:
Low lying placenta or placenta previa: If the placenta remains implanted in the lower part of the uterus even as you enter the 33rd–34th week, it may result in a placenta previa or low lying placenta, often requiring you to have c-section delivery [2, 7]. Some studies suggest an association between an anterior placenta previa and a higher risk of preterm delivery .
Back labor: Women with an anterior placenta may have back labor, contributing to severe back pain and painful contractions during labor. However, it may depend on various factors, like your baby’s position in the womb as well as your own health. Some women report of having no back labor when their babies were also anterior, meaning the baby facing the mother’s belly. According to some, you are more likely to have back pain during labor if your baby is facing your spine (posterior baby).
One study found anterior placental implantation to have an association with higher chances of gestational diabetes, pregnancy-induced hypertension, placental abruption as well as intrauterine growth retardation.
Having a c-section with an anterior placenta
The placenta may make it a bit difficult to have a c-section delivery if it is lying low at the front of the uterus, just below the spot where your doctor needs to make the cut to deliver your baby. It may increase your risk of bleeding during the surgery . An ultrasound may be used to assess the exact location of the placenta so the cut can be made a little higher to reduce the chances of bleeding.
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