An anterior placenta – the one at the front of the uterus – is very common and rarely causes any problems in pregnancy. “The placenta works the same, providing nutrients and oxygen to your baby, no matter where it is,” says Shannon Smith, MD, an ob/gyn at Brigham Faulkner Ob/Gyn AssociatesOpens a new window and a member of the BabyCenter Medical Advisory Board.

However, having an anterior placenta can make it difficult to feel your baby’s early kicks. This is because the placenta creates a barrier between your baby and the skin nerves in your stomach when it is in front.

Also, placing the placenta in front—where it can block sound waves—can make it harder for your doctor or midwife to hear your baby’s heartbeat using a doppler. And it can make amniocentesis more difficult if you have one. (However, your doctor may use an ultrasound to safely guide the procedure.)

What is the anterior placenta?

The placenta is located where the fertilized egg attaches to the wall of the uterus. An anterior placenta means that the placenta is in front of your uterus.

Other places where the placenta can implant are:

• The back of the uterus (posterior placenta)
• Top of uterus (fundal placenta)
• Left or right side of the uterus (lateral placenta)
• Lying low, towards the bottom of the uterus. In this case, the placenta sometimes covers all or part of the cervix (placental previa).

It is possible for the location of the anterior placenta to change as your belly grows, so that it is located higher in the uterus. It doesn’t actually move, explains dr. Smith, but as the uterus grows, the lower part grows, so the placenta appears to move up.

How common is placenta previa?

Experts estimate that as much as half of all pregnant women have an anterior placenta.

According to one studyOpens a new window of more than 74,000 women who gave birth to their first baby, 48% had an anterior placenta in the second trimester, while 46% had a posterior placenta. (Others had fundal or lateral locations.)

We don’t know why the egg sometimes implants in the front, but one studyOpens a new window of 500 pregnant women suggests that sleeping on your back can encourage implantation of the egg in the front of the uterus.

The placenta can change position early in pregnancy as your uterus grows, so your doctor or midwife won’t confirm its position until around 20 weeks, when you have your mid-pregnancy ultrasound.

Are there any advantages to having an anterior placenta?

“There are no known advantages of an anterior placenta,” says Dr. Smith.

It might seem logical that an anterior placenta would provide a bit of extra cushioning for your baby – an extra layer of protection if your tummy gets bumped, for example. But there is no evidence that this is true and, if you have any trauma to your abdomen, your doctor will be equally concerned regardless of where the placenta is.

The placenta works the same way, providing nutrients and oxygen to your baby, no matter where it is.

– Shannon Smith, MD, OB/GYN and member of the BabyCenter Medical Advisory Board

Will an anterior placenta affect the shape of my belly?

No, the anterior placenta should not affect the shape of your stomach. Even though it’s right in front, it’s pancake-shaped and quite thin.

Will the baby’s kicks feel different with an anterior placenta?

An anterior placenta can make it difficult to feel your baby kick or move because the placenta acts as a cushion between your belly and baby. You may not feel your baby kick until 20 weeks (when the kicks are stronger) instead of the usual 18 weeks or so. Their kicks may also be harder to feel on the outside of your belly.

Women with anterior placentas in the BabyCenter community Pregnancy group have experienced this phenomenon:

“I didn’t feel the first flutters early in my pregnancy. I started feeling the baby’s movements around 21 weeks.” – tinyheat

“I didn’t really feel her move until 24 weeks. Now I feel her all the time. It’s frustrating to wait, but it’s worth it when you finally feel your baby.” – Steph Boothe

“It took a little longer, but around 25 weeks I really started feeling those kicks on the outside. I’m 31 weeks now and feel him all day. I swear he never sleeps!” – hopeful102109

Also, if you have an anterior placenta, you may feel the baby kick from the side rather than in the middle.

How does the anterior placenta affect childbirth?

An anterior placenta usually does not cause any problems, although it can increase the chance that your baby will be in the “sunny side up” position (head down, back to your back, face up). This can put pressure on your back during labor, resulting in a painful birth.

An anterior placenta also increases the risk of:

Placenta accreta. If you have had a C-section or other uterine surgery in the past, and the placenta is implanted over an old scar on the uterus, there is an increased risk of placenta accreta, which means the placenta has entered the uterus too deeply. This is a serious potential pregnancy complication that should be carefully evaluated with ultrasound during pregnancy, says Dr. Smith.

Placenta previa. Placenta previa is more likely with an anterior placenta. (This might be seen on your anatomy ultrasound when you’re about 20 weeks pregnant.) If the placenta lies above the cervix (or is low-lying), there is an increased chance of bleeding complications in the second and third trimesters.

If it stays there when it’s time to give birth, you’ll need a C-section. But in 90% of cases, the placenta moves higher in the uterus before delivery. And with an anterior placenta, placenta previa is even more likely to resolve.

You can definitely have a vaginal birth with placenta previa. But if you also have a complication such as placenta accreta or placenta previa that doesn’t resolve before delivery, you may need a C-section.