Some women give birth early because of their medical history or because they develop a medical condition during pregnancy. Sometimes a woman's lifestyle means she may be more likely to give birth early, for example if she smokes or if she is obese.
The care you receive to reduce the likelihood of giving birth early will depend on your medical risk factors, and you may also be given advice about lifestyle changes that you could make. Smoking increases your chances of giving birth prematurely so if you smoke you will be encouraged to quit. Obesity also increases the risks of giving birth early, so if your body mass index is too high you will be given advice on how to stop putting on more weight by eating healthily and taking exercise.
Sometimes, you may be considered at risk because there is a problem with the placenta or your uterus; in these cases you will be monitored more closely for signs of early labour, or signs that your baby is not growing properly. If the doctors think that your or the baby’s health is at risk it may be best to deliver your baby early by induction or caesarian section. If you go into labour suddenly, it may be possible to stop its progress, although this is not always be the best thing to do.
If you are at risk of premature birth your doctor or midwife can do a fetal fibronectin test which can predict you likely you are to give birth prematurely.
Your pregnancy history
At your first antenatal appointment your midwife will use your medical history and any problems in past pregnancies to decide if you are at risk of premature birth. Your care will be tailored to your specific risk factors to reduce the chances of giving birth early. If your midwife thinks that you may give birth early, you will have antenatal appointmentsmore often and you will have extra tests and checks to make sure that you and your baby ore doing fine.
If you have an infection
If the normal bugs that live on the skin and in the vagina get into the membranes (the ‘sac’) that surrounds your baby this could cause premature birth. It is not always clear why this happens. Urinary tract infections are common in pregnancy and should always be treated. More rarely, bacteria in some foods and sexually transmitted diseases can affect the baby in the womb. If you have signs that you may have an infection, or if tests show that you have an infection, you may be given antiobiotics to clear it, however it is not yet known to what extent antibiotics can prevent premature birth.
If you have pre-eclampsia
Up to 10 percent of premature births are the result of the pregnancy related condition pre-eclampsia and eclampsia. Eclampsia is a more serious form of pre-eclampsia and it can cause seizures, liver and kidney failure, difficulty with breathing and blood clots. It can also affect the baby's growth, and can be life-threatening to both mother and baby. If you develop pre-eclampsia you will have extra checks and appointments to monitor the baby’s wellbeing, and you may have to take medicine to lower your blood pressure. If the pre-eclampsia is severe or turns to eclampsia you will have to give birth early.
If there is a problem with your cervix (cervical weakness or incompetence)
Sometimes the cervix can become damaged through past cervical surgery or childbirth. When this happens the cervix is called weak or incompetent, which means it could open or shorten before you reach term and lead to your baby being born prematurely. If scans show that there is a problem with your cervix you may be offered a cervical stich (also known as a cerclage or cervical suture) to stop your baby being born too soon.
If you have diabetes or you develop gestational diabetes
If you have diabetes it is important that you have good control of your blood glucose before you get pregnant to lessen the risks to you and your baby. Your GP or diabetes specialist will explain how to do this. Once you are pregnant you and your baby will be closely monitored. If you use insulin to control your blood glucose the healthcare team will give you advice on how to change your usual dose to fit in with your pregnancy needs. You may have to stop or change other medication you were on before you became pregnant.
If you develop gestational diabetes during your pregnancy you will be given advice on exercise and diet and nutrition to help keep your blood glucose levels in the right range. You will be taught how to monitor your blood glucose. In some cases you may have to medicine to control the diabetes.
Women with diabetes are advised to take higher doses of folic acid than women without diabetes to try and prevent birth defects such as spina bifida. Folic acid should be taken until you are 12 weeks pregnant.
If you bleed after 24 weeks
Bleeding after the first trimester is a sign that there is a problem with the placenta, and this can cause premature birth. It is impossible to predict what will happen or how early you will have to give birth. You will have regular extra scans to see if the placenta rises back up into your womb, and you will be explained what to do if you have bleeding, contractions or pain. If you have severe bleeding this puts your and the baby’s life at risk and you may have to deliver the baby prematurely through caesarean section.
If you are carrying more than one baby
Carrying twins or more is a major risk for preterm labour. If you are carrying more than one baby you will be offered regular tests to check if you are developing high blood pressure or anaemia (lack of iron), and you will have ultrasound scans more often to measure your babies’ growth. It is a good idea to talk about birth options with your midwife or consultant early in the pregnancy and to plan the best place to give birth to your baby. As you are more likely to give birth before 38 weeks you may be given information on corticosteroids to mature your babies’ lungs and reduce the likelihood of your babies needing to go to the special care unit in the event of early delivery.
If your waters break early
Waters breaking before 37 weeks causes about 20% of premature births. It is unclear why sometimes the waters break early, but it is thought that smoking, vaginal bleeding, a weak cervix, and infection could play a role. If your waters break early you should call your midwife or doctor and go to hospital where you will have checks and test to try find out if you are in labour and why your membranes have broken. If there are signs that you are in labour you may be given tocolytic drugs to try to stop contractions, although this does not necessarily improve the outcome for the baby and is not always recommended. Your doctor will advise you according to your own case. If doctors think that delivery is very likely, and depending how many weeks pregnant you are, you may also be given a dose of magnesium sulphate and corticosteroids to help protect your baby's brain and lungs.
If there is a problem with your womb
Premature birth is more likely if there is a problem with the shape of your womb, or if is there is an obstruction, for example a fibroid. This is because the baby will run out of space in which to grow, or in some cases because the shape of your uterus encourages the development of twins. If there is a problem with your womb your baby’s growth will be measured more often and you may have to give birth by caesarean section.
If there is a problem with how your baby is developing
The antenatal checks and tests that you have are there to make sure that everything with you and your baby is fine. However sometimes these tests show that there is a problem with how your baby is developing and there are several reasons why this may be happening. In some cases the best thing will be for your baby to be delivered early.
Antiphospholipid antibody syndrome
If you already know you have APS, tell your GP or midwife as soon as you know you are pregnant so you can get the right treatment. Although APS cannot be cured, its complications and symptoms, including pregnancy complications, can be reduced. If APS is suspected due to recurrent miscarriage or other symptoms, you will be offered a test for the syndrome. This will be done with two blood tests at least 6-12 weeks apart.
If it is established that you are in labour, the healthcare team will try to prevent the birth of your baby if possible and if it does not endanger the baby. This is so that they can do their best to prepare you and your baby for their premature birth.
Some common questions about the different risks of premature birth and how you can reduce them.
It's not easy for the healthcare team to discover why some babies are born prematurely, but there are steps that can be taken that can slightly reduce your risk of premature birth.
The tests and checks you're offered during pregnancy will help the healthcare team work out if you are at risk of giving birth prematurely.
Most preterm babies arrive early without warning. However, some pregnancies are known to be at risk of ending in preterm birth.
The placenta is your baby’s support system in the womb. If your placenta doesn’t work properly, your baby is at risk of health problems.
- Macdonald S, Magill-Cuerden J, Mayes’ midwifery, fourteenth edition, Edinburgh Bailliere Tindall Elsevier, 2012
- National Institute for Health and Care Excellence, Pre-term labour and birth: draft scope, London NICE, 2014
- Royal College of Obstetricians and Gynaecologists, Preterm birth - study group statement, London RCOG, 2004
- National Institute for Health and Care Excellence, Hypertension in pregnancy, clinical guideline 107, London NICE, 2011
- National Institute for Health and Care Excellence, Diabetes in pregnancy, clinical guideline 63, London NICE, 2008
- Royal College of Obstetricians and Gynaecologists, Placenta praevia, placenta praevia accreta and vasa praevia: diagnosis and management, green-top guideline 27, London RCOG, 2011
- National Institute for Health and Care Excellence, Multiple pregnancy, clinical guideline 129, London NICE, 2011