Written by Beata Anderson
The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby’s blood. The placenta attaches to the wall of your uterus, and your baby’s umbilical cord arises from it. The placenta is usually attached to the top, side, front or back of the uterus. In rare cases, the placenta might attach in the lower area of the uterus. When this happens, it’s called a low-lying placenta.
What affects your placenta’s health?
Various factors can affect the health of the placenta during pregnancy, with some under your control and but most not. For example:
- Maternal age. Some placental problems can occur more common in women after age 40.
- A break in your water before labour. During pregnancy, your baby is surrounded by a fluid-filled membrane called the amniotic sac. If the sac leaks or breaks before labour begins, also called your water breaking, the risk of certain placental problems increases.
- High blood pressure. High blood pressure can affect your placenta.
- Twin or other multiple pregnancy. If you’re pregnant with more than one baby, you might be at increased risk of certain placental problems.
- Blood-clotting disorders. Any condition that either impairs your blood’s ability to clot or increases its likelihood of clotting increases the risk of certain placental problems.
- Previous uterine surgery. If you’ve had a previous surgery on your uterus, such as a C-section or surgery to remove fibroids, you’re at increased risk of certain placental problems.
- Previous placental problems. If you’ve had a placental problem during a previous pregnancy, you might have a higher risk of experiencing it again.
- Substance use. Certain placental problems are more common in women who smoke or use cocaine during pregnancy.
- Abdominal trauma. Trauma to your abdomen — such as from a fall, auto accident or other type of blow — increases the risk of the placenta prematurely separating from the uterus (placenta abruption)
What complications can affect the placenta?
Complications that can affect the placenta during pregnancy or childbirth include:
- low-lying placenta
- retained placenta – when part of the placenta remains in the uterus after giving birth
- placental abruption – when the placenta starts to come away from the wall of the womb
These complications aren’t common.
Low-lying placenta
As your pregnancy progresses, your womb expands and this affects the placenta’s position. The area where the placenta is attached usually stretches upwards, away from your cervix. If the placenta stays low in your womb, near to or covering your cervix, it may block the baby’s way out. This is called low-lying placenta or placenta praevia. It affects about 1 in every 200 births, but in most cases the cervix is not completely covered.
The position of your placenta will be checked at your 18 to 21 week routine anomaly scan. If your placenta appears low, you’ll be offered an extra ultrasound scan later in your pregnancy (usually at about 32 weeks) to check its position again. For 9 in every 10 women, the placenta will have moved into the upper part of the womb by this point. If the placenta is still too close to the cervix, they will refer you to see an obstetrician to discuss your delivery and give you information regarding to your risks in the last trimester of your pregnancy. If the placenta is too near or covering the cervix, your baby can’t be delivered through the vagina, so a caesarean section will be recommended.
Placental abruption
Placental abruption is an uncommon yet serious complication of pregnancy. Placental abruption occurs when the placenta partly or completely separates from the inner wall of the uterus before delivery. This can decrease or block the baby’s supply of oxygen and nutrients and cause heavy bleeding in the mother. Placental abruption is most likely to occur in the last trimester of pregnancy, especially in the last few weeks before birth. Placental abruption requires immediate medical attention.
Retained placenta
It happens when during delivery not all the placenta is delivered. Midwives who are supporting you during delivery will check if your placenta you delivered appears to be complete and whole. If they believe that is not the case or you have continuous heavy bleeding for many weeks after delivery you may require an internal ultrasound scan to assess your uterus.