Placenta previa: marginal or complete, causes and risks for the baby

Placenta previa: marginal or complete, causes and risks for the baby
Source: Shutterstock

Previous placenta

  • what is that
  • what are the symptoms and how to diagnose
  • consequences of marginal placenta previa
  • consequences of central placenta previa
  • causes and risk factors

How do you know you have placenta previa?

It usually turns out to have the previous placenta when morphological ultrasound is done in the second trimester. With previous ultrasound scans it is difficult to establish whether the placenta is really previa, because it may be that, despite being inserted in bass, it "rises" as the size of the uterus increases, to a point where it no longer gives problems. For this reason, the position of the placenta is checked (if necessary with transavaginal ultrasounds) even in the last weeks of pregnancy. 

Only one in ten women who are diagnosed a low placenta in the early stages of pregnancy it will come to term with a truly previa placenta. 

Placenta previa it hardly gives symptoms in the first months of pregnancy, while towards the end of the second trimester and throughout the third trimester it can cause vaginal bleeding. The bleeding tends to be painless (although in some cases it can be accompanied by uterine contractions and pains), the blood is often bright red, and the discharge can be massive. Symptoms and consequences, however, they also depend on the type of placenta previa, which can be marginal or central.


Placenta previa in pregnancy - PHOTO

go to the gallery

Placenta previa is a situation in which the placenta inserts itself into the lower part of the uterus, covering part or all of the uterine orifice, a ...

What is meant by placenta previa?

The term "placenta previa" refers to a situation in which the placenta inserts itself into the lower part of the uterus, partially or completely covering the uterine orifice, a kind of funnel that leads to the cervix. Under normal conditions, the placenta implants itself in the upper part of the uterine cavity, but in one case out of about 200-250 it can settle in the lower part.

The presence of placenta previa can cause vaginal bleeding major and other complications particularly during the last months of pregnancy. Since during the labor The uterine orifice dilates to allow the passage of the fetus, this could cause sudden abruption of the placenta, potentially very dangerous for mother and baby. 

Read also: Anterior placenta

Marginal placenta previa

If placenta previa is marginal, it means that the placenta is positioned within the lower segment of the uterus, but does not completely cover the internal uterine orifice.

"This type of placenta previa can give a few episodes of bleeding: as the uterus grows, in fact, small detachments can occur in the lower part, which however generally do not cause serious consequences for the mother and fetus "explains, director of the obstetrics and gynecology department at the Buzzi Hospital in La our city and professor of the University of our city. "In case of blood loss, however, it is sIt is always a good idea to contact your gynecologist or hospital for a check-up".

The marginal placenta previa it is not an absolute contraindication to the Partor vaginal.

Read also: Losses in the first trimester of pregnancy, how to behave

Central placenta previa

If placenta previa is Central, means that the placenta completely covers the internal uterine orifice. "It is a much more risky situation, because it can provoke heavy and sudden bleeding, which always require a medical check-up and, in some cases, hospitalization ", he stresses." For this reason, it is advisable for women to be followed by a level II center, where more frequent checks will be carried out ".

If the blood loss is very severe, a blood transfusion may be required and delivery may be required before term, with the risks to the fetus associated with this condition. 

It is generally recommended to lead a life of rest, avoiding exertion (it's prudent too avoid sexual intercourse). In the last weeks of pregnancy, when the uterus normally begins its contractile activity, the placenta may begin to detach, causing bleeding, which require a emergency cesarean.

In any case, when the placenta is central previa, a scheduled cesarean delivery, because at the time of labor, with the dilation of the uterine neck, a detachment of the placenta would be determined, with a very high risk of fetal suffering.

Read also: Flowmetry or Doppler in pregnancy: used to evaluate fetal circulation and placenta

Causes and risk factors

We do not know what the precise causes of placenta previa are, but we do know however that the risk of a low insertion increases in some surroundings and in particular:

  • previous caesarean section;
  • uterine abnormalities that inhibit proper implantation (fibroids);
  • previous curettage;
  • have already had a pregnancy with placenta previa;
  • previous uterine surgery;
  • maternal age over 35;
  • twin pregnancy;
  • smoking habit

Sources for this article

  • Medline Plus website
  • web page of the American Mayo Clinic
  • advice from, director of the obstetrics and gynecology department of the Buzzi Hospital in our city
  • MSD manual for professionals

To learn more

  • the placenta
  • placenta and pregnancy
  • anterior placenta
  • placenta accreta
  • placental abruption in pregnancy

Placenta previa in pregnancy: the testimonies of mothers

Here are the testimonies of mothers who said they had placenta previa during pregnancy. 

1. "Placenta previa centrale": story of my Federico, born at 32 weeks

I am the mother of a child born at 32 weeks plus 2. I'll tell you the story of my pregnancy and my birth. Upon returning from the New Year's Eve in Paris in January 2022, I discover that my little Federico is inside me. What a joy! The magic begins, I start fantasizing about the future and watching my belly grow until July 11th. On that very day, at 6.00 in the morning, I get out of bed and notice specks of blood, then a big loss, then wake up my husband and go running to the hospital. The verdict is: "central placenta previa". Immediately after vasosuprina, drip and then transfer by ambulance to the San Camillo di of the city.

2. Placenta previa and difficult delivery: my daughter and I were lucky

I have experienced a difficult pregnancy due to a placenta previa detachment. Luckily my daughter was born healthy and the birth went well. But my experience was really bad: the doctors told us that we were lucky, if I had had the detachment at home, my daughter would not have made it and, most likely, neither would I. It was very bad not to have her with me, not being able to squeeze her or breastfeed her immediately, a real pain. After 10 days finally, the three of us were happy together at home.

Questions and answers

Is vaginal birth always absolutely excluded with placenta previa?

If the placenta previa is marginal and the placenta does not cover the uterine orifice, the medical team, in agreement with the mother, can evaluate the possibility of a vaginal birth.

Does placenta previa affect the position of the fetus in the womb?

Yes, in the case of placenta previa it is more common for the baby to be in the breech or transverse position. 

  • placenta previa pregnancy
  • low placenta
  • fetus position
  • uterus
  • give birth
add a comment of Placenta previa: marginal or complete, causes and risks for the baby
Comment sent successfully! We will review it in the next few hours.