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Anterior Placenta Complications, Risks, and Delivery

Usually, the placenta is located behind the baby (posterior placenta); if the placenta is located in front of the baby, it's called an anterior placenta.
A doctor showing an ultrasound scan to his patient with an anterior placenta

In most cases, anterior placentas do not cause a high risk of complications to the baby, the mother, or the delivery itself; in fact, as a pregnancy moves forward toward delivery, the placenta may shift or migrate multiple times.

Placenta development stages

The placenta has a unique role in the female body. It's considered an organ, but in contrast to other organs like the kidneys and liver, it's only present when a woman is pregnant. The placenta and fetus begin the development process together. In the earliest days of pregnancy, a developing blastocyst —an early stage embryo — embeds itself in the wall of the uterus. Soon after, the structure of uterine blood vessels undergoes a transformation that allows increased blood flow to the fetus and placenta, enabling them to begin growing faster.

As the placenta grows, it keeps pace with the fetus to deliver oxygen, immunities, and important nutrients. By the end of the first trimester, around 12 weeks into the pregnancy, the placenta reaches its full capabilities as a support organ to the fetus, as well as a barrier against any other outside factors. The placenta also manages the excretion of waste.

How common is anterior placenta?

Developing an anterior placenta is very common during pregnancy. Various studies show that between one-quarter and one-half of all pregnancies will at some point have a placenta in a position in front of the fetus. In most cases, this will not cause a risk to the pregnancy.

Placenta in the front: is it ok?

In government-funded studies, several potential complications of having a placenta in front of the fetus were found. Most were very mild issues, such as:

  • Difficulty in feeling a baby kick, because the placenta serves as a shield between the baby and the mother’s abdomen
  • Issues with health care providers locating fetal heart sounds due to dampening from the placenta
  • Challenges in conducting an amniocentesis

More serious risks could include hypertension, gestational diabetes, and, rarely, placental abruption, when the placenta detaches from the uterine wall. In studies, these risks occurred in only a very small number of pregnancies that featured anterior placental placement.

A doctor locating fetal heart sounds

Anterior vs posterior placenta

The two primary locations for a placenta during pregnancy are anterior and posterior, which translates to in front of and behind the baby, respectively. Other less common placements include a fundal placenta, at the top of the uterus; fundal anterior; fundal posterior; and placenta previa, when the organ locates itself at the bottom of the uterus.

Anterior placenta baby movement

A placenta in front of the baby serves as cushioning between the growing baby and the mother’s abdomen so that the feel of a baby’s movement can be muted or even nonexistent. Many women with an anterior placenta are still able to feel their baby kick or move, just not as strongly as in pregnancies with a posterior placenta. Pregnant women may still feel strong movements along their sides or the lowest part of the abdomen, where the anterior placenta does not buffer kicks. As the baby grows larger and stronger, especially after 20 weeks of pregnancy and well into the third trimester, more of their movement may be felt through the placenta and abdomen.

Anterior placenta ultrasound

An anterior placenta can make certain tests trickier to conduct during pregnancy. For instance, fetal heart rate monitors or dopplers can struggle to pick up the baby’s heartbeat, instead capturing the mother’s heart rate beating through the placenta. Anterior placenta ultrasounds are typically still able to provide good imaging of the baby by essentially “looking” through the placenta and at the baby. At times, depending on the exact position of the placenta, the baby’s location and position can be difficult to discern.

Anterior placenta complications

Anterior placenta complications won’t harm a growing baby during pregnancy but can lead to some difficulties during birth. For example, low-lying anterior placenta can cause a condition known as placenta previa. In this case placenta partially or fully blocks the cervix resulting in a need for cesarean delivery. Rarer complications can include a higher chance of developing high blood pressure and gestational diabetes, which can occur during any pregnancy but are slightly more likely with an anterior placenta.

Anterior placenta risks

Women with an anterior placenta can run the risk of experiencing excessive bleeding. As the pregnancy draws to a close, the exact position of the placenta is typically studied carefully through ultrasound, as any migration to the lower portion of the uterus can result in difficult labor. Mothers may also experience back labor, which can be extremely painful. Back labor pains may also be harder to control through typical pain relief methods during labor.

Anterior placenta delivery

Most babies born to mothers with an anterior placenta are delivered without any complications. Once labor begins, health care professionals examine the mother to ensure that an anterior low-lying placenta isn’t blocking the vaginal canal. If no blockage is found, an uncomplicated vaginal delivery is usually possible. If ultrasounds are unable to fully reveal the baby’s position, an unexpected breech birth may occur. Because of the placenta’s anterior position, doctors may be unable to manipulate the baby to avoid a breech birth. In that case, the baby’s breech position may lead to increased bleeding during delivery. Caesarian sections can also be difficult when the placenta is anterior as incisions in the abdomen must be very carefully made to avoid cutting the placenta, which could cause heavy bleeding. An anterior placenta should pose no greater risk of a retained placenta.

https://www.nichd.nih.gov/research/supported/HPP/research_funding/human-placenta

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3935544/

https://www.whattoexpect.com/pregnancy/ask-heidi/anterior-placenta.aspx

https://www.healthline.com/health/pregnancy/anterior-placenta#1

https://www.medicinenet.com/pregnancy_placenta_previa/article.htm

https://www.emedicinehealth.com/placenta_previa_in_pregnancy/article_em.htm

https://www.mamanatural.com/anterior-placenta/

https://parenting.firstcry.com/articles/common-placenta-positions-an-overview/

https://www.kickscount.org.uk/anterior-placenta

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