Placenta Previa



Offer Erez,Lena Novack, Vered Klaitman, Idit Erez-Weiss, Ruthy Beer-Weisel,Doron Dukler, and Moshe Mazor 

Placenta previa is a risk factor for preterm birth and contributes to about 5% of all preterm deliveries. The prevalence of placenta previa is 0.3-0.5% of pregnancies, and the risk for this complication increases according to the number of prior caesarean deliveries. Placenta previa is associated with an increased maternal morbidity including the need for blood and blood products transfusion, urgent caesarean section, and caesarean hysterectomy. Moreover, a higher rate of perinatal mortality and morbidity, especially respiratory distress syndrome and anaemia are associated with this abnormal placentation. 

Most of the patients with placenta previa are delivered preterm, and these deliveries are regarded as indicated preterm births due to excessive maternal haemorrhage.  

Nevertheless, recent evidence suggests that other mechanisms aside bleeding may lead to preterm birth in women with placenta previa. Patients with placenta previa who delivered preterm had a higher rate of intra-amniotic infection/inflammation than those who delivered at term, suggesting that similarly to spontaneous preterm birth, intra-amniotic infection or inflammation may contribute to the process of preterm parturition in patients with placenta previa. Moreover, women with this complication who had a short cervical length have an increased risk to deliver preterm. Thus, the mechanisms leading to spontaneous preterm parturition may play a similar role in patients with placenta previa who deliver prematurely. 


Placenta previa is a pregnancy related condition where the placenta implants at the bottom of the uterus, either completely covering the cervix or partially covering it. The placenta provides oxygen and nutrients from the mother’s bloodstream to the baby. Typically, in early pregnancy, the placenta sits low in the uterus and as it grows it moves away from the cervix. By the third trimester, the placenta should be away from the cervix, however with placenta previa, the placenta covers or is close to the cervical opening When a baby is preparing to be born, the cervix dilates to enable the baby to move out of the uterus and into the vagina. In women with placenta previa, the risk is that the blood vessels connecting the placenta to the uterus may tear, this bleeding may put mother and baby at a serious risk. In woman with placenta previa, the baby generally cannot be born vaginally due to the threat of bleeding, therefore almost all women who experience this condition will require a C section to deliver the baby safely.  

The symptoms of placental previa are: 

  • Bright red vaginal bleeding with no pain, generally during the second half of pregnancy  

The possible causes and risk factors are: 

  • Scarring of the uterus 
  • Abnormally shaped uterus 
  • Pregnant with multiples 
  • Previous pregnancies 
  • Smoking 
  • Previous C-section 
  • Advanced maternal age 
  • Placenta previa in previous pregnancies 


Placenta previa is generally diagnosed during a routine ultrasound. There is no cure or treatment for placenta previa, the goal is to limit any bleeding to enable your baby to grow and get close to full term. Your health professional may give you medication to prevent premature labour from occurring and may give you corticosteroids (to help develop your baby’s lungs) if premature birth is a possibility. If the bleeding experienced is light, it may be suggested that you avoid activities such as sex and exercise. If the bleeding is heavy, you may need to stay in hospital for foetal monitoring and you may possibly need blood transfusions. 

The complications of placenta previa include: 

  • Major maternal bleeding and subsequent shock from blood loss 
  • Foetal distress from lack of oxygen 
  • Premature birth and the subsequent health risks for the baby 
  • Emergency C section 
  • Hysterectomy 
  • Death 


It is important to remember that bleeding during pregnancy is not uncommon and is not always a sign of placenta previa or other serious pregnancy related conditions. If you are experiencing any concerning symptoms, as well as bleeding, it is important to be thoroughly checked over by your health professional. 

Receiving a diagnosis of placenta previa after the anticipation and excitement of a healthy pregnancy may be shocking, stressful and frustrating. You may benefit emotionally from connecting with other woman who have or are experiencing the same condition and journey. Speak to your doctor or midwife about finding these support groups.  

In severe cases bed rest or a hospital admission may be necessary for the health and wellbeing of you and your unborn baby. Extended periods away from home and loved ones can be difficult and support is important.  You may need to be sent to a tertiary hospital where the best possible care is available for you and your baby. You may be introduced to a maternal foetal specialist who will discuss your care dependent on your condition and the health of your baby. If an early delivery is a possibility, you doctor may choose to administer steroid injections to help develop the baby’s lungs which can help prevent respiratory distress once your baby is born.  

It may now be the time to consider the likelihood of experiencing a premature birth and to ask any questions about what to expect. Visiting the Neonatal Intensive Care Unit (NICU) or Special Care Nursery (SCN) will help you become familiar with the environment and talking to health care professionals about what to expect at your baby’s gestation can be beneficial. 


Useful Links 

COPE – Centre for Perinatal Excellence 

Through the Unexpected – Perinatal Diagnosis 

Panda - Perinatal Mental Health 




Confirmation Content

Disclaimer: This publication by Miracle Babies Foundation is intended solely for general education and assistance and it is it is not medical advice or a healthcare recommendation. It should not be used for the purpose of medical diagnosis or treatment for any individual condition. This publication has been developed by our Parent Advisory Team (all who are parents of premature and sick babies) and has been reviewed and approved by a Clinical Advisory Team. This publication is not a substitute for professional medical advice. Miracle Babies Foundation recommends that professional medical advice and services be sought out from a qualified healthcare provider familiar with your personal circumstances. To the extent permitted by law, Miracle Babies Foundation excludes and disclaims any liability of any kind (directly or indirectly arising) to any reader of this publication who acts or does not act in reliance wholly or partly on the content of this general publication. If you would like to provide any feedback on the information please email [email protected].