Pre-existing medical conditions



Developed by the National Guideline Alliance hosted by the Royal College of Obstetricians and Gynaecologists 

Risk assessment and planning are key components of individualised care for pregnant women, so that any factors likely to affect the pregnancy or birth can be identified in a timely manner. This guideline deals with care for women at higher risk of complications in labour and birth, either because of an existing medical condition or because obstetric complications develop. With appropriate risk assessment and care planning, care can be delivered to maximise the chances of good outcomes for both the woman and her baby. Assessment and planning start at the antenatal booking appointment and continue throughout pregnancy at each antenatal contact. During labour, routine monitoring of the woman and her unborn baby and of the progress of labour is a continuation of the risk-screening process. Findings from these assessments will affect the plan of care for labour and may result in changes to the plan being made antenatally or during labour if new complications are identified. 


Conditions such as rhesus negative blood group, gestational diabetes, diabetes, kidney disease and high blood pressure can all affect a developing baby. In some cases, the decision to deliver a baby prematurely is because either they or the mother are medically unwell due to a health problem, congenital abnormality, or surgical need.  

High Blood Pressure 

High Blood Pressure can cause premature birth for your baby during pregnancy. High blood pressure occurs when your blood vessels constrict increasing the pressure in these vessels. During pregnancy if the placenta does not receive enough blood, the baby might not receive enough oxygen and nutrients which can lead to pre-eclampsia, slow growth, low birth weight or premature birth. 

Symptoms of high blood pressure: 

  • Severe headaches 
  • Nausea and vomiting 
  • Swelling 
  • Chest pain 
  • Shortness of break 
  • Protein in the urine 

Ways to prevent high blood pressure before pregnancy: 

  • Eat healthy foods 
  • Get daily exercise 
  • Get to a healthy weight 
  • Avoid smoking and drinking alcohol 

Sometimes medication is required when lifestyle changes do not work. It is important to monitor and treat high blood pressure during pregnancy as left untreated it can be life threatening for mother and baby. 


Diabetes occurs when your body has too much sugar or glucose in the blood. Your body does not make enough of the hormone called insulin that helps your body keep the right amount of glucose in your blood.  If you have pre-existing diabetes before pregnancy you will need to plan your pregnancy and get it under control before you get pregnant. It will be important to have a healthy diet and exercise and your doctor will recommend you take folic acid every day. Once you do get pregnant you will also need to be monitored carefully during your pregnancy. Your doctor will want you to check your blood sugars regularly and to take more insulin if required. 

Babies born to women with diabetes are at risk of being born larger than average and born premature. They are also at risk of developing type 2 diabetes in the future. Managing diabetes can help reduce the risk of complications. 

Gestational Diabetes 

Gestational diabetes occurs when you have too much sugar in your blood during pregnancy. Your sugar levels can go up when your body is not producing enough of a hormone called insulin. 

Symptoms of gestational diabetes are: 

  • Feeling more thirsty 
  • Needing to pee more frequently 
  • Felling more tired 
  • Getting recurring UTI’s

You will be offered a test called the Glucose tolerance test between week 24 and 28 of your pregnancy to check if you have gestational diabetes. 

Gestational diabetes is treated by healthy eating and exercise, and it is important that it is monitored and treated during your pregnancy as it could lead to high blood pressure and preeclampsia and other complications for you and your baby. 

Kidney Disease 

Kidney Disease in pregnancy is another cause of premature birth. 

A doctor will check if your kidneys are functioning properly by doing a urine test for proteins. If proteins are found in your urine it means that the kidneys are not filtering as they should be.  

Some of the symptoms of kidney disease are: 

  • Fluid retention which can cause swelling 
  • Changes to frequency and colour of urine 
  • High blood pressure 
  • Nausea and vomiting 

It is important to monitor and treat it in pregnancy as it can lead to complications such as high blood pressure and pre-eclampsia. 

Rhesus negative blood group 

Everybody has one of 4 blood types (A, B, AB or O). You inherit your blood group from your parents. These blood types are further identified as being either positive or negative. (For example, your blood type can be A positive or A negative). This shows your 'Rhesus factor' (RhD), which states if you have a protein known as 'D antigen' on the surface of your red blood cells. 

Around 1 in 6 people in Australia have a negative blood type. Being RhD negative isn’t usually a problem unless you are pregnant, and your baby happens to be RhD positive. This can happen if the baby’s biological father is RhD positive. 

Problems can occur if a small amount of your baby’s blood enters your bloodstream during pregnancy or birth. This may cause your body to make antibodies against the rhesus positive cells (known as ‘anti-D antibodies’). This is called a 'sensitising event'. 

A ‘sensitising event’ can occur: 

  • during some tests you may have during your pregnancy (such as chorionic villus sampling (CVS) or amniocentesis) 
  • after miscarriage or termination 
  • after an injury or accident to your abdomen 
  • if your baby is in a breech position and you have an external cephalic version (where doctors turn the baby around inside the womb) 
  • during labour 

A sensitising event usually does not affect your first pregnancy. However, if you have another pregnancy with a rhesus positive baby, your immune response will be greater, and you may make many more antibodies. These antibodies can cross the placenta and destroy your baby’s red blood cells. This may lead to a condition called 'rhesus disease', or 'haemolytic disease of the new-born', causing anaemia, jaundice, and brain damage in the baby. 

Rhesus disease is uncommon these days. It can usually be prevented with injections of a medicine called 'anti-D immunoglobulin'. You will be offered blood tests as part of your antenatal screening, so you will be told if your blood is RhD negative or positive. 

You will be offered an injection at 28 and 34 weeks of pregnancy if your blood is rhesus negative. It may also be given at other times if there is concern about a sensitising event. 

Currently, the only way to find out if a baby is RhD positive is after they are born, and the umbilical blood can be tested. You can have the injection after your baby is born and tests show your baby is RhD positive, but doctors recommend that if you are RhD negative, you have it while you are pregnant. 

The anti-D injection is safe for both you and your baby. If you have already developed anti-D antibodies in a previous pregnancy you will not need another injection in your next pregnancy. Your future pregnancies will be monitored more closely than usual, as will the baby after birth. 


In all pre-existing conditions it is important to pre-plan your pregnancy closely with your doctor to be in the optimum condition for your pregnancy. 

A healthy diet and weight and exercise before you get pregnant will help and sometimes your doctor will prescribe medication if required. It is also important to have your pregnancy monitored closely by your obstetrician so that any issues can be treated in time to avoid further complications for you and your baby. 

Useful links 


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].