Absolute Risk is the chance of a problem occurring, usually expressed as one in 100, one in 1000 etc.

ARM (artificial rupture of the membranes) is a method of augmentation in which a midwife or doctor breaks the membranes which surround the baby in the womb using a special device. This requires an internal vaginal examination.

Assisted Birth is a birth which is assisted by a doctor using either forceps or a ventouse to help get a baby out of the birth canal by turning and/or pulling on the baby’s head while the mother pushes. This may be offered if:

  • The second (‘pushing’) stage of labour has gone on for a long time
  • A baby’s head is not in a good position for birth and needs to be turned
  • If there are signs suggesting that a baby is not coping well during this stage.

For more information on this including the pros and cons of forceps and ventouse see

Augmentation is the use of medical procedures (ARM and/or a synthetic oxytocin drip) intended to start or strengthen labour contractions. These may be used as part of the process of induction following the use of prostaglandin or a mechanical method. They may also be used to try to speed up a labour which started spontaneously, if progress is thought to be too slow.

Birth plan is a statement of your preferences for labour and birth, to share with your midwife.

Bishop’s score is an estimate of how close active labour is to starting, based on a
midwife’s judgement of the following factors:

  • Dilation: How far the cervix has opened.
  • Effacement: How much the cervix has thinned.
  • Station: How far down in the pelvis the baby has moved.
  • Consistency: How soft the cervix has become.
  • Position: How far forward the cervix is.

The midwife assesses the cervix while performing an internal vaginal examination and feels the bump to work out where baby’s head is in relation to the pelvis. The midwife allocates zero, one or two points for how far each of the changes has progressed, then add them up to give a total score. A lot depends on the midwife’s judgement, so it’s far from an exact science.

BBA (Born Before Arrival) is where a midwife does not arrive at a birth before the baby is born. This is a category which is recorded in UK National birth statistics.

Caesarean is a procedure to birth a baby through a surgical opening in the abdomen and womb. You can find out more about the benefits and risks of caesareans in the NICE guideline (NICE 2011) and in this article on the AIMS website

Cerebral palsy is the name given to a group of conditions that have a life-long effect on movement and co-ordination. Most cases occur as a result of problems with the development of a baby’s brain during pregnancy. It can also be caused by something that damages the brain during labour or soon after birth, such as low oxygen, low blood sugar or an infection like meningitis.

Continuous monitoring is the use of a machine to track how a baby’s heart is responding over time and to look back at the history of how the response has changed through labour. It is usual for a midwife to monitor a baby’s heartrate during labour to check how they are responding to labour contractions. For straightforward pregnancies it is recommended that this is done intermittently (from time to time) using either a small stethoscope or a hand-held ultrasound device. Continuous monitoring is usually offered if medical interventions such as an epidural or an oxytocin drip are being used, because of the extra stress that these may put on the baby. For more about the pros and cons of continuous monitoring see

Cross-over is where high numbers of people ended up having the opposite treatment or care to the one that was intended. Some cross-over in a randomised controlled trial (RCT) is expected, even for an RCT on caesareans some women allocated to a planned caesarean will go into labour before it can be done, and other who are in the planned vaginal birth group will need a caesarean. For example in research on induction of labour it is quite common for a high proportion of those allocated to the expectant management (waiting for labour) group to have their labours induced because they have reached a pre-set deadline for the birth to take place or some concern has arisen before their labour began. Similarly, some of those allocated to the induction group may go into labour before the induction is started. For results to remain valid this cross-over needs to remain low.

Early birth is a birth that is brought forward from the time at which spontaneous labour would have started, either by medical induction or a planned caesarean. In some cases, it is used to mean an induced or caesarean birth that takes place before full-term (40 weeks).

Early term birth is a birth that occurs after 37 full weeks of pregnancy but before the start of the 39th week. Though considered ‘term’ these babies are more likely to experience health problems including breathing difficulties than those born after the start of the 39th week.

Elective birth - see Planned birth

Epidural (more accurately epidural analgesia) is a form of pain relief in which a fine needle is inserted into the space around the spinal cord and a tube is passed through this. The needle is taken out, and drugs are given through the tube to numb the nerves which carry messages about pain to the brain. The drugs are usually a mixture of a local anaesthetic and an opiate (morphine-like) drug.

Expectant management is waiting for labour to start spontaneously rather than inducing it at a certain point in pregnancy. Additional monitoring is usually offered during this time. In some cases induction or a caesarean birth will be offered at a later point in pregnancy, if labour has not begun spontaneously.

Fetal compromise is diagnosed when there are signs of serious problems with a baby’s well-being, such as reduced blood flow in the blood vessels of the placenta or concerns over the baby’s heart rate.

Fetal growth charts are used to check on how a baby is growing in the womb and to provide an estimate of what the birthweight will be. They may either record a midwife’s regular measurements of how the ‘bump’ is growing or use ultrasound measurements of the baby’s size.

Fetal Growth Restriction is the situation where a baby’s normal growth is being affected by some problem, causing them to be smaller than expected. The causes of fetal growth restriction can include genetic problems, infection, or a problem with the working of the placenta. This is not the same as SGA as some small babies are growing as they should but are naturally small.

Forceps are a pair of metal instruments which look a bit like large spoons and can be fitted around a baby’s head to enable a doctor to turn and/or pull the baby out. See also Assisted birth

Freebirth/Freebirthing is where a woman or pregnant person intentionally gives birth to a baby without a midwife or doctor present. Some people prefer to use the term unassisted childbirth. For more information please see the AIMS Birth Information page Freebirth, Unassisted Childbirth and Unassisted Pregnancy

GDG (Guideline Development Group) is a group of people responsible for drafting guidelines such as the NICE Guidelines. In the case of NICE guidelines they will agree the review questions, consider the evidence and develop the recommendations. The GDG normally includes both healthcare and other professionals and user representatives.

Instrumental birth - see Assisted birth

LGA (large-for-gestational-age) describes a baby who is at the upper end of the weight-range for that point in pregnancy. The usual definition is that a baby is LGA if they have an actual birthweight over 4000g (4kg or 8lb 13oz) or an estimated fetal weight which is in the top 90% of the population at that point in pregnancy. This means they are above the 90th centile on their growth chart.

Macrosomia/macrosomic - see LGA

Meta-analysis is a type of review of research evidence which combines the data from a number of randomised controlled trials. This can help to overcome the problem of such trials having too small a sample to detect a difference in rare outcomes, but the approach has limitations. For more on this see the AIMS Birth Information webpage Understanding Quantitative Research Evidence.

Neonatal death is the death of baby within the first 28 days after birth. This is sometimes divided into early neonatal deaths which happen in the first week and late neonatal deaths which are between seven and 28 days after birth.

Observational studies - see Population studies

Ongoing pregnancies is an estimate of how many people in a group were still pregnant at a certain week of pregnancy. It is considered that looking at the number of stillbirths per 1000 ongoing pregnancies gives a more accurate view of the risk than looking at the number of stillbirths per 1000 births in that week

Oxytocin is a hormone which is produced in the brain during labour and stimulates the muscles of the womb to contract. It also has a positive effect on mood and promotes bonding between partners, parents and babies. A synthetic version of the same substance may be given through a drip into the hand or arm as a method of augmentation to try to start or strengthen contractions.

Perinatal deaths are the total deaths of babies beyond 24 weeks of pregnancy that occur before or during labour (stillbirths), plus those that occur shortly after birth (neonatal deaths). Usually this includes only neonatal deaths up to seven days after birth, but sometimes those occurring up to 28 days after birth (referred to as extended perinatal deaths).

Planned birth is one that is planned to take place at a certain point in pregnancy, either by induction or a planned caesarean.

Population studies (also known as observational studies) are studies that look at how outcomes differ between groups defined by one or more characteristics such as their age, or by a difference in the treatment that they receive. Mostly these are ‘retrospective studies’ which look back at the records of a population, often over a period of years. There are also ‘prospective studies’ which define the groups to be studied at the start of the research and then follow up what happens to people in these groups. For more on this see the AIMS Birth Information webpage Understanding Quantitative Research Evidence.

Pre-eclampsia is a usually mild but potential serious complication of pregnancy, which should be monitored closely, and may require a planned early birth (induction or caesarean). The main symptoms are high blood pressure and protein in the urine, which is why these are tested for at routine antenatal appointments.

Pre-term or premature birth is a birth which occurs before the end of the 37th week of pregnancy.

Prostaglandins are chemicals made by the body which have similar effects to hormones but are produced and act locally. There are many different types, including those that cause ripening of cervix in preparation for labour to begin. A version of these natural substances can be applied as a pessary as a way of inducing labour.

Randomised controlled trial (RCT) A form of research study where people are randomly divided into two or more groups, each of which receives a different treatment, so that the outcomes can be compared. Ideally, such trials would be ‘blinded’, which means that neither the person in the trial, nor those caring for them know which group they are in. This is not usually possible in research about labour and birth. For more on this see the AIMS Birth Information webpage Understanding Quantitative Research Evidence.

Relative risk is a measure of how much more common it is for a problem to occur in one group compared with another. For example, if a problem is observed twice as often in group B as in group A, then the relative risk for group B compared with group A would be 2.

SGA (small-for-gestational-age) describes a baby who is at the lower end of the weight-range for that point in pregnancy. The usual definition is that a baby is SGA if they have an actual birthweight or an estimated fetal weight which is in the lowest 10% of the population at that point in pregnancy. This means they are below the 10th centile on their growth chart. It is not the same as fetal growth restriction, as not all SGA babies are growing poorly in the womb – some are naturally small.

Statistically significant means that a result that is highly unlikely to have occurred by chance. Note that this is a technical use of the word ‘significant’. It’s not saying anything about the importance of the finding. For more on this see the AIMS Birth Information webpage Understanding Quantitative Research Evidence.

Stillbirth is the death of baby that occurs after 24 weeks of pregnancy and before or during labour. Those that happen before labour starts are sometimes called ‘antepartum stillbirths’ and those that occur during labour as ‘intrapartum stillbirths’. Those that occur before 24 weeks of pregnancy are referred to as miscarriages.

Term birth is a birth which occurs between the 37th and 42nd weeks of pregnancy.

Unassisted Childbirth, more commonly known as freebirth, is where a woman or pregnant person intentionally gives birth to a baby without a midwife or doctor present. For more information please see the AIMS Birth Information page Freebirth, Unassisted Childbirth and Unassisted Pregnancy

Ventouse (see also Assisted birth) consists of a plastic or metal cup which is placed on a baby’s head and connected to a suction device. The suction creates a vacuum inside the cup so that it stays on the baby’s head while the doctor or midwife pulls the baby out.

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