Low Lying Placenta & Placenta Praevia

Following conception, the placenta implants itself somewhere in your uterus, in no specific position.

After an ultrasound, you may be told that you have a low-lying placenta or your placenta may be covering your cervix, meaning the placenta has implanted low down in your uterus. This is reported in around 5% of pregnancies at the 18-20 week scan. There is no need to worry if you are amongst this 5% – you can continue your daily activities as per normal unless you have been advised otherwise.

In your third trimester (until around 36 weeks) the bottom part of your uterus does most of it’s growing and stretching, taking the placenta with it. It doesn’t ‘migrate’ upwards, but being attached to the uterine wall, it’s carried upwards with it. In 0.5% of cases, the placenta doesn’t move up with the uterus – so given that small percent, there is an extremely good chance that your placenta will not be covering your cervix when it’s time to give birth, enabling you to have a vaginal birth.

If you have a low lying placenta at 18-20 weeks, this does not mean you need a caesarean section. The placenta will highly likely move as mentioned above. The uterus still has much growing to do, so an ultrasound late in your third trimester will give you and your carer a better picture on what’s really going on and if it really is of concern.

Placenta Praevia

Placenta Praevia (which means placenta first) is a rare condition which occurs in around 0.5% of pregnancies. Instead of implanting on the uterine wall, the placenta implants partly or wholly over the cervix.

How Do I Know If I Have Placenta Praevia?

Placenta Praevia is usually detected by ultrasound and/or bleeding in pregnancy. The first bleed most commonly occurs at around 34-38 weeks of pregnancy, but may occur sooner or later than this. It doesn’t always lead to pre-term birth, but it is more common. Some women never experience any bleeding at all but any painless blood loss should be reported.

It is important to be reminded that it’s the mothers blood which is lost, not the babies. The more centrally the placenta is situated over the cervix, the earlier the haemorrhage and the greater the amount of blood lost.

What Causes Placenta Praevia?

The cause is often unknown and is less common in first pregnancies. Placenta Praevia may be found in multiple pregnancies as a result of a larger surface area of the placenta, or from scarring on the lining of your uterus from a previous caesarean section or curette etc. Some studies have recently shown that those using ART (assisted reproductive technology) to be another possibility for Placenta Praevia. The late implantation of the fertilised ovum i.e. conception late in the cycle, will result in the fertilised ovum settling in lower down the uterine wall than if conception takes place at ovulation where it settles in high up in the uterine cavity. It has also been suggested that doctors are inserting embryos lower in the uterus to aim for higher success rates.

Given that caesarean sections are on the increase, along with ART, this may see an increase in the incidence of Placenta Praevia.

What If I Have Placenta Praevia?

If you have Placenta Praevia, you will likely need to birth your baby by caesarean section depending on the grade or degree of Placenta Praevia. You may be able to birth vaginally if you have a grade 1 or 2 Placenta Praevia, however if you have grades 3 or 4, a caesarean section will be necessary. This wont be booked in immediately, if you don’t go into labour before hand, you will likely be booked in at around 38 weeks when your baby is more mature. If you go into labour prior to this you will need an emergency caesarean. A grade 4 Placenta Praevia will often mean being admitted to hospital at the first bleed and remaining as an inpatient until birth.

Some women may find the thought of a caesarean upsetting, not being able to birth their baby vaginally and may feel like their birth will be a failure. However birthing your baby by caesarean is not a failure – it’s the safest way (perhaps only way!) to bring your baby into the world and is the safest way for mum too. If you have trouble dealing with your emotions, it’s important to seek the help of an experienced psychologist or support groups for caesarean healing. Try the Birthrites website for more info.

Kelly Zantey is a birth attendant (aka doula) the creator of BellyBelly, mum to two beautiful children and has just opened the BellyBelly Pregnancy Centre in Canterbury, VIC. Article proof-read by BellyBelly Midwife, Brenda Manning.

To read more pregnancy articles, please click here.