Placenta Praevia - Low Lying Placenta

Placenta praevia

If you are told by your practitioner that you have a low-lying placenta, then it means that your placenta is sitting below the baby and is either partially or fully covering the cervix. The potential complications associated with this condition are nothing to worry about until your third trimester, but it is usually detected at the second routine ultrasound scan which takes place at around 20 weeks. The placenta is not fixed in one place and it is quite normal for it to move around the uterus during pregnancy, in actual fact, a low-lying placenta is common during the early stages of pregnancy. As the uterus grows, the placenta usually moves upwards until it is at the top of the uterus and the opening to the cervix is clear for childbirth. By full-term, only about 1 in 200 pregnancies still have placenta praevia. However, the condition is not usually described as placenta praevia until about 32 weeks. This is when you will be asked to attend an additional ultrasound scan to ensure that the placenta has moved to a safe place in the uterus. Note that only women shown with a low-lying placenta at 20 weeks will need to have this 32 week scan.

There are three different degrees of placenta praevia:

• Marginal - where the placenta is in contact with the cervix but not covering the opening.
• Partial - where the placenta covers part of the opening of the cervix.
• Complete - where the entrance to the cervix is fully covered by the placenta.

There is nothing that can be done to prevent placenta praevia but there are factors that increase the risk of it occurring, these include:

• Pregnancy in women over the age of 30.
• Second or subsequent pregnancies.
• Pregnancy in women who have had previous uterine surgery, such as caesarean section, or a D&C (Dilation & Curettage) if a previous pregnancy ended in miscarriage.

What does placenta praevia mean for my pregnancy?

Placenta praevia will not affect your pregnancy until the later stages. If the placenta doesn't move of its own accord then you will have to have the baby via caesarean section. This is because a natural delivery could cause serious damage to the placenta and put the baby's health at risk. The biggest concern prior to this is that you may experience some vaginal bleeding. If this happens then it is very important that you contact your midwife or GP immediately and follow their advice. You will be examined and may be hospitalised if the bleeding persists. At the very least you will be advised to limit your physical activities or possibly even to take complete bed rest, with no sexual intercourse. Your healthcare team will do their best to ensure that the baby does not have to be delivered early, although even without bleeding it is likely that your caesarean section will be scheduled for about 37 weeks. This is to avoid the possibility of you going into labour with the placenta at risk of being damaged. It that did happen, the mother would require an emergency caesarean section.