Posterior Low Lying Placenta: What Does It Mean?

A posterior low-lying placenta is when the placenta is abnormally positioned and lies very low in the uterus, behind the baby.

In the majority of pregnancies, the placenta attaches to either the front or back of the uterus, but there are times when it can attach lower down. This can cause some complications and may need you to take action.

There are quite a lot of serious consequences, including a higher risk for miscarriage, preeclampsia (high blood pressure during pregnancy), gestational diabetes, and premature delivery, related to a posterior low-lying placenta. However, although it sounds scary, most women still manage to carry a healthy baby to term with placenta previa. This article will outline what posterior low-lying placenta is, why it happens, and how it can affect your pregnancy.

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So what even is a posterior low lying placenta (also known as placenta previa or praevia)  and how does it occur?

The placenta is the organ that develops to help your baby to grow healthily and usually attaches to the lining of the womb on the front or back. It connects to the baby by the umbilical cord.

A low-lying placenta is a placenta that is lying less than 0.079 in (2 mm) away from the cervix opening. It is typically detected during an ultrasound when it appears on the left side of the uterus and causes a reduced amount of amniotic fluid. Low-lying placentas can lead to preterm births and can cause serious health issues for both mother and baby.

Posterior low-lying placentas are those that move towards the back, or rear, of the uterus. They are a common cause of preterm labor and birth. Posterior placenta praevia is a specific type of posterior low lying placenta, which occurs when the entire placenta is found to be in the back half of the uterus. This can cause miscarriage and severe bleeding after delivery and the baby may need to be delivered early for his or her own health. Posterior low-lying placentas can also affect the baby's heartbeat, as it may make it difficult for the mother's cervix to dilate properly during childbirth. Placenta praevia occurs when the placenta attaches completely covering the cervix, which can be even more dangerous for pregnant women and their babies.

Your placenta position will usually be checked during your second trimester ultrasound scan, which is at around weeks 18 to 21 of your pregnancy. If your doctor diagnoses the placenta as low-lying, then you will need to have another scan at 32 weeks to monitor it.

A low-lying placenta is a condition that occurs in about 20% of all pregnancies. Oftentimes it isn't anything to worry about, and as the placenta grows the location of the placenta can move to a different part of the uterus. In fact, 90% of women that have a low-lying placenta in the second trimester will not still have a low-lying placenta in the third trimester.

For women who have had a Cesarean delivery before, it is less likely for the placenta to move upwards in placement during this time, but only one in 200 women have placenta praevia by the end of their pregnancy so the risk is actually not that high. It is possible for a woman to have a normal delivery with a low-lying placenta, and often the pregnancy can be successfully carried until the baby is due, with the correct guidance and support from your doctor of course.

A posterior low-lying placenta can cause a number of complications and can be dangerous for the mother and baby, so it's important for diagnosis and management to stay as safe as possible.

Most women who have a posterior low lying placenta carry their babies to term successfully. However, one study found that the rate of premature delivery was 41%. Of the women who did deliver prematurely, there can be a number of other complications.

It is important to know that with most cases of placenta praevia or a low-lying placenta, a baby is carried healthily to term and naturally birthed, as long as it is diagnosed and managed by your doctor early on in pregnancy.

A posterior low-lying placenta is one of the major risk factors for prematurity and miscarriage. The condition can be more likely to occur when a woman is carrying twins or in a higher number multiple pregnancy.

A posterior placenta can affect labor because a lower-lying placenta does not allow for the proper flow of nutrients to the developing fetus. Additionally, it also carries more risks for a woman because it may lead to a miscarriage or pre-term labor. The condition can also cause severe and heavy bleeding during delivery or even beforehand, which is why it can be dangerous to both mother and child.

There are a few symptoms that usually occur when you are experiencing placenta previa or a low-lying placenta. These include:

Bleeding: Placental problems like placenta accreta and vasa and placenta previa are the most common medical reason for heavy bleeding in the third trimester of pregnancy. The bleeding may be bright red and painless and is common in about two out of three women suffering from placenta previa. It's important to note that one in three women do not have any bleeding at all.

Cramping: Cramping in conjunction with bleeding, feeling like contractions is quite unusual but does occur in some women with a low lying placenta or placenta praevia.

Breech: If you have a low-lying placenta, it might cause your baby to be in a breech position. During the third trimester, your baby will usually move its head down to the bottom of the uterus for comfort, but when the placenta is obstructing the opening to the cervix, then your baby might end up being in a breech position to have more space for their head.

You may be more at risk of developing a low lying placenta or placenta previa if you fit any of the following criteria:

You are aged over 30.

You are pregnant with multiples. Twins or more will increase the risk of the placenta being in the wrong place.

You smoke or take drugs during pregnancy. Cocaine and cigarettes increase your chances of the placenta being low lying or placenta previa occurring, as well as being risk factors for many other medical complications.

This pregnancy is not your first. Usually, placenta previa is more likely to be diagnosed in women who have already had one or more pregnancies.

You have already had a C-section or other kind of uterine surgery. This can cause scarring on the uterus that means your placenta may struggle to latch onto the walls of the uterus where it needs to be, which can result in the placenta being low lying.

You are using IVF (in vitro fertilization) to get pregnant. IVF has often been linked to placental problems and placenta previa.

Some research has also been done that suggests that if you are either an Asian or Black woman, you might have a higher risk of placenta previa.

There are a few precautions that your doctor or medical professional may suggest if you have the diagnosis of a posterior low lying placenta or placenta previa.

There is no way for your doctor to prevent internal placenta previa, and unfortunately, there isn't any available medical treatment that is able to correct the problem before birth. However, treatment can be provided for any heavy bleeding you might be experiencing, so that you and your baby do not experience any risks relating to blood loss.

1. When you experience only light bleeding in the third trimester of pregnancy, from placenta previa or a low-lying placenta, then your doctor may suggest for you to avoid activities that could aggravate the area. This usually will include sexual intercourse and certain or all types of exercise and is called pelvic rest. Occasionally you may be prescribed bed rest to keep risks to the absolute minimum.

2. If you are experiencing heavier vaginal bleeding due to your placenta previa, then you may have torn the blood vessels that connect the placenta to the uterus. If you are bleeding heavily, you should contact a health professional straight away for treatment to minimize blood loss.

3. If the bleeding is uncontrolled, and your baby is distressed then you may be at risk of early birth, so should go straight to the emergency room.

4. Your doctor may suggest increasing their monitoring of your baby with an ultrasound or scan to check their heartbeat and that they are moving around as they should be.

5. For some women, medication can be provided to prevent early labor, especially if a doctor is worried that your pregnancy may be earlier than 36 weeks.

6. On some occasions, hospital care will be recommended in the week or two before delivery, especially if you have been bleeding heavily at any point.

7. Most women will deliver by C-section if they have placenta previa, as natural delivery is a risk in this situation to both baby and mother, and could potentially even have life-threatening consequences. Around two-thirds of C-sections due to placenta praevia will be pre-scheduled for before labor begins.

8. If you experience any severe bleeding after your baby is at 36 weeks, then your doctor may recommend that you have a Cesarean delivery immediately.

It's important to note that placenta previa is not hugely dangerous for a mother or baby, but the bleeding that can be caused by it, and the potential of preterm birth are the risks that will be carefully monitored by your health professional to prevent any further complications.

The complications that could occur include preterm birth, placenta accreta (which is when the placenta attaches too deeply to the uterine wall), vasa previa (which is a very rare complication), a hemorrhage, hysterectomy, and an increase in the risk of having placenta previa and preterm birth in any future pregnancies.

Though it sounds very scary, placenta previa will almost always be monitored very carefully by your doctor after your second ultrasound, and knowing what the risks are and when to seek treatment will help you to deliver your baby healthily.

If you found this article helpful, then why not take a look at our guide to itchy nipples during pregnancy, or experiencing a plus size pregnancy?