Placenta previa is a condition that affects one in 200 pregnancies.
It involves the placenta implanting at the bottom of the uterus, where it covers the cervix.
When a woman is pregnant, the placenta plays a vital role in that it ensures that the baby has oxygen and nutrients from the mother’s bloodstream as it grows. However, when a woman is suffering from placenta previa, her placenta will obstruct the cervix, leading to issues with delivery.
During labour, the cervix dilates to allow the baby to slide from the uterus, into the vagina, and out into the world. Placenta previa stops this from happening because the cervix is covered, meaning the baby cannot be born naturally. There are two levels of placenta previa: Partial placenta previa, which means only some of the cervix is blocked and complete placenta previa, which means all of the cervix is blocked. A C-Section is required for birthing.
Symptoms and Diagnosis
Many women do not realise they have placenta previa until scans or physical examinations show the issue. However, some mothers do experience painless vaginal bleeding at around 20 weeks. Of course, placenta previa is not the only cause of bleeding around this time, but any woman experiencing bleeding should go to their doctor if they are pregnant.
In the case of placenta previa, the bleeding is caused by the bottom part of the uterus thinning and spreading to make room for the baby as it grows. When the placenta is attached to the bottom of the uterus, this thinning can separate the placenta and result in bleeding. Sex can also cause bleeding when a woman has placenta previa, particularly later in the pregnancy.
There isn’t one single thing that causes placenta previa, but there are some risk factors associated with the condition. These include a low implantation of the egg once fertilised, any kind of abnormality in the uterine lining, such as fibroids, scarring of the uterine lining and abnormalities in the placenta. Placenta previa is also more likely to occur when a woman has delivered six or more babies, or in cases where the birth is a multiple one, such as with twins or triplets.
Other risk factors with placenta previa include:
- Former surgeries where uterine fibroids have been removed
- Older than 35 years
- More common in non-caucasian women
- Cocaine Use
Doctors will usually be able to tell you if you have placenta previa based either on an ultrasound scan, or by feeling the belly to see where the baby is lying. When the baby is sideways, or in a breech position (bottom first), then placenta previa is present in about one in three cases.
In come cases, it can be difficult to see whether a woman is suffering from placenta previa or placental abruption. The latter is a condition where the placenta has separated from the uterine wall. Both conditions are usually heralded by heavy bleeding of blood that is bright red in colour. A vaginal examination is often used to determine whether placental abruption is behind the bleeding. However, if the woman is actually suffering from placenta previa, this vaginal examination could trigger more heavy bleeding. For this reason, an ultrasound scan should always be done first.