Presentation
The part of the foetus related to the pelvic brim and first felt during vaginal examination.
The presentation may be:
Cephalic (96%):
Vertex: when the head is flexed.
Face: when the head is extended.
Brow: when it is midway between flexion and extension.
Breech (3.5%).
Shoulder (0.5%).
Cephalic presentation is the commonest as this makes the foetus more adapted to the pyriform-shaped uterus with the larger buttock in the wider fundus and the smaller head in the narrower lower part of the uterus.
Position
The relation of the foetal back to the right or left side of the mother and whether it is directed anteriorly or posteriorly.
The denominator: is a bony landmark on the presenting part used to denote the position.
In vertex it is the occiput.
In face it is the mentum (chin).
In breech it is the sacrum.
In shoulder it is the scapula.
Occipito-anterior positions are more common than occipito- posterior positions because in occipito- anterior positions the concavity of the anterior aspect of the foetus due to its flexion fits with the convexity of the vertebral column of the mother due to its lumbar lordosis.
In each presentation, except the shoulder, there are 8 positions. In vertex presentation they are:
Left occipito -anterior (LOA) 60%.
Right occipito-anterior (ROA) 20%.
Right occipito posterior (ROP) 15%.
Left occipito-posterior (LOP)5%.
Left occipito-transverse (LOT).
Right occipito transverse (ROT).
Direct occipito -anterior (DOA).
Direct occipito-posterior (DOP).
LOA is more common than ROA, and ROP is more common than LOP as in LOA and ROP the head enters the pelvis in the right oblique diameter which is more favourable than the left oblique because:
anatomically, the right oblique is slightly longer than the left,
the pelvic colon reduces the length of the left oblique.
Attitude
The relation of foetal parts to each other.
Flexion in the majority of cases.
Extension in face presentation.
Synclitism
The posture in which the 2 parietal bones are at the same level.
Asynclitism
The posture in which one parietal bone is at a lower level than the other due to lateral inclination of the head.
Asynclitism is beneficial in bringing the shorter subparietal supraparietal diameter (9 cm) to enter the pelvis instead of the longer biparietal (9.5 cm).
Slight degree of asynclitism may occur in normal labour.
Anterior parietal bone presentation
The anterior parietal bone is lower and the sagittal suture is near to the promontory.
It occurs more in multigravidas due to laxity of the abdominal wall.
It occurs also in contracted flat pelvis.
Posterior parietal bone presentation
The posterior parietal bone is lower and the sagittal suture is near to the symphysis.
It occurs more in the primigravidas due to tense abdominal wall.
Anterior parietal bone presentation is more favourable because:
The head lies more in the direction of the axis of the pelvic inlet.
During correction of asynclitism, the head meets only the resistance of the sacral promontory while in posterior parietal bone presentation the head meets the resistance of the whole length of the symphysis pubis.
In posterior parietal bone presentation the head stretches the anterior wall of the lower uterine segment with liability to rupture.
Engagement
It is the passage of the widest transverse diameter of the presenting part, which is the biparietal in vertex presentation, through the pelvic inlet.
The engaged head cannot be easily grasped by the first pelvic grip, but it can be palpated by the second pelvic grip.
Rule of fifths: 2/5 or less of the foetal head is felt abdominally above the symphysis pubis.
Vaginally : the vertex is felt vaginally at or below the level of ischial spines.
Stations
Station 0 the vertex at the level of ischial spines.
Stations -1, 2 and 3 represent 1, 2 and 3 cm respectively above the level of ischial spines.
Stations +1, +2 and +3 represent 1, 2 and 3 cm respectively below the level of ischial spines.
In the primigravida, engagement of the head occurs in the last 3-4 weeks of pregnancy due to the tonicity of the abdominal and uterine muscles.
In the multipara, the head is usually engaged at the onset of labour or even at the beginning of the second stage due to less tonicity.
Causes of non-engagement
Faults in the passenger:
Large head.
Hydrocephalus.
Occipito-posterior positions.
Malpresentations.
Multiple pregnancy.
Placenta praevia.
Short cord.
Polyhydramnios.
Faults in the passages:
Contracted pelvis.
Pelvic tumours.
Full bladder or rectum.
Faults in the power:
Atony of the abdominal muscles.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------What is pre-conceptual care?
A healthy couple generally leads to a healthy pregnancy, and therefore a healthy baby. Attending to a woman's health even before she is pregnant can limit the chances of problems with the health of the subsequent baby. This is particularly important because in the very early weeks of pregnancy the mother may not even know she is pregnant but this is the time when very important stages in the formation of the baby are taking place so it is even more crucial that the risks to the growing baby are reduced to a minimum and there are certain things that a woman can do to achieve this. This is called pre-conceptual care i.e. care of the woman even before she has conceived.
What does pre-conceptual care involve?
Generally pre-conceptual care simply means that a couple should become as healthy as possible and follow certain simple advice that has been found to increase the chances of having a healthy baby. There is nothing complicated about it but the woman may want to talk things over with her doctor before conceiving especially if she has certain health problems of her own. Below are the most important aspects that doctors advise a woman should consider before trying for a baby.
Smoking
Stopping smoking is probably the single most important thing that a woman and her partner can do towards having a healthy baby. Men who smoke tend to have lower sperm counts and the sperm they do produce show high numbers of abnormal sperm, thereby reducing the chances of conception in the first place. Smoking during pregnancy is the main cause of low birthweight babies. Also smoking puts the pregnancy at higher risk of miscarrying or going into premature labour and it is equally important to continue not smoking after the baby has arrived since babies born into a household where there is a smoker are more at risk of cot death, chest infections and asthma.
Folic acid
The vitamin folic acid reduces the chance of a baby being born with spina bifida. Spina bifida is a disability caused by a malformation of the spine and, since the spine is formed very early in pregnancy, occurs in the first few weeks after conception and can result in the baby being born with severe paralysis of part of the body. Spina bifida may be associated with hydrocephalus, when fluid collects near the brain. About 400 babies a year in the UK are born severely disabled by spina bifida but research has shown that folic acid prevents three out of four cases.
Although there are many foods that contain this vitamin (such as vegetables, cereals and beans) the simplest way to supplement the diet to provide a sufficient amount of folic acid to give this beneficial effect is to take a tablet every day. A recent Government recommendation advises all women to commence folic acid at a dosage of 0.4 milligrams (400 micrograms) a day if they are contemplating a pregnancy. They should be taken from the moment the woman begins trying to conceive until the twelfth week of pregnancy.
There is no need for any other vitamin or mineral supplements before or during pregnancy unless the woman is a strict vegan when it is probably advisable for her to take iron and multivitamin supplements. Vegans who wish to take folic acid should seek further advice from their GP as some multivitamins have an excess of recommended daily allowance. A well balanced diet provides all the necessary vitamins and minerals for pregnancy.
Rubella (German measles) immunity
Rubella (also known as German measles) is usually a very mild illness in adults and children, usually involving a slight temperature and a rash and in these situations it is usually harmless. However, if a pregnant woman contracts rubella especially in the early stages of pregnancy it can cause damage to the baby including deafness, blindness and heart defects. Most women will be immune to rubella because they will have been given the rubella vaccine at school. However, some will have missed the vaccine and there are other women who, despite having been given the vaccine, lose immunity as the years go by.
Therefore, it is advisable for a woman to have her rubella immunity checked by her doctor with a simple blood test since, if she is not immune, she can be immunised before she becomes pregnant. If this does happen she will be advised by her doctor not to become pregnant for three months after the immunisation since it is thought that there may be a risk to a baby conceived in the three months following the injection. Leaving the blood test until pregnancy occurs is too late for that pregnancy since, if the mother is found to be not immune, the immunisation cannot be given whilst pregnant. She is at risk if she comes into contact with someone who has illness. Therefore the sensible measure is to have one's rubella immunity checked before becoming pregnant.
Diet
It is easy to become over anxious about diet before and during pregnancy especially since a number of 'scares' in the media a few years ago. Therefore it is worth saying that as long as a woman eats a healthy well balanced diet and tries to maintain a normal weight she is extremely unlikely to develop any problems with her pregnancy. There are one or two foods that are best avoided during pregnancy and in the pre-conceptual period, such as soft or blue-veined cheeses, pate, liver and raw meat.
As far as body weight is concerned it is sensible to try to attain a normal weight for a variety of reasons not least of which is that it could be extremely uncomfortable being overweight and pregnant. Also if any complications arise during pregnancy or labour it is usually much easier for the doctors to deal with these problems if the mother is not overweight. Finally, the risk of developing blood pressure problems in pregnancy is greater if the mother is obese.
Alcohol
There is no need to stop drinking alcohol before a pregnancy or even during pregnancy but heavy drinking is harmful both to the woman and (if she is pregnant) to the unborn child, so it is advisable to restrict alcohol intake to modest amounts and certainly less than fourteen units a week in the pre-conceptual period. (A unit of alcohol is equivalent to half a pint of beer, a glass of wine or a measure of spirits.)
Medication
Those women on regular medication from their doctor should check, before they become pregnant, that their tablets are safe in pregnancy. Most are, but there are one or two which the doctor may wish to change before conception. For instance some blood pressure drugs and most anti-epileptic drugs can affect the foetus. If a woman is trying for a baby it is also sensible to mention this to the doctor if he is prescribing for her since some commonly prescribed drugs are not suitable in pregnancy such as some antibiotics, anti-inflammatory painkillers and some hormone tablets.
Genetic counselling
Couples with a close family history of, or a previous child with, any disorder that is inherited (such as cystic fibrosis or muscular dystrophy) should seek medical advice regarding the chances of a subsequent child having the same disorder. The GP may seek further advice from a specialist in genetic counselling to help such couples to decide whether or not to go ahead with a pregnancy. In some cases, a certain amount of screening of the couple can be done to provide a better estimate of the chances of an affected baby. For some conditions further tests can be done in early pregnancy to enable the couple to decide whether or not to continue with the pregnancy. It is probable that this area will attain increasing significance in terms of screening in the years to come.
Exercise
Regular exercise is recommended in the pre-conceptual period as it is for normal living. Pregnancy and labour are physically demanding and therefore it makes sense to be as fit as possible before becoming pregnant.
The part of the foetus related to the pelvic brim and first felt during vaginal examination.
The presentation may be:
Cephalic (96%):
Vertex: when the head is flexed.
Face: when the head is extended.
Brow: when it is midway between flexion and extension.
Breech (3.5%).
Shoulder (0.5%).
Cephalic presentation is the commonest as this makes the foetus more adapted to the pyriform-shaped uterus with the larger buttock in the wider fundus and the smaller head in the narrower lower part of the uterus.
Position
The relation of the foetal back to the right or left side of the mother and whether it is directed anteriorly or posteriorly.
The denominator: is a bony landmark on the presenting part used to denote the position.
In vertex it is the occiput.
In face it is the mentum (chin).
In breech it is the sacrum.
In shoulder it is the scapula.
Occipito-anterior positions are more common than occipito- posterior positions because in occipito- anterior positions the concavity of the anterior aspect of the foetus due to its flexion fits with the convexity of the vertebral column of the mother due to its lumbar lordosis.
In each presentation, except the shoulder, there are 8 positions. In vertex presentation they are:
Left occipito -anterior (LOA) 60%.
Right occipito-anterior (ROA) 20%.
Right occipito posterior (ROP) 15%.
Left occipito-posterior (LOP)5%.
Left occipito-transverse (LOT).
Right occipito transverse (ROT).
Direct occipito -anterior (DOA).
Direct occipito-posterior (DOP).
LOA is more common than ROA, and ROP is more common than LOP as in LOA and ROP the head enters the pelvis in the right oblique diameter which is more favourable than the left oblique because:
anatomically, the right oblique is slightly longer than the left,
the pelvic colon reduces the length of the left oblique.
Attitude
The relation of foetal parts to each other.
Flexion in the majority of cases.
Extension in face presentation.
Synclitism
The posture in which the 2 parietal bones are at the same level.
Asynclitism
The posture in which one parietal bone is at a lower level than the other due to lateral inclination of the head.
Asynclitism is beneficial in bringing the shorter subparietal supraparietal diameter (9 cm) to enter the pelvis instead of the longer biparietal (9.5 cm).
Slight degree of asynclitism may occur in normal labour.
Anterior parietal bone presentation
The anterior parietal bone is lower and the sagittal suture is near to the promontory.
It occurs more in multigravidas due to laxity of the abdominal wall.
It occurs also in contracted flat pelvis.
Posterior parietal bone presentation
The posterior parietal bone is lower and the sagittal suture is near to the symphysis.
It occurs more in the primigravidas due to tense abdominal wall.
Anterior parietal bone presentation is more favourable because:
The head lies more in the direction of the axis of the pelvic inlet.
During correction of asynclitism, the head meets only the resistance of the sacral promontory while in posterior parietal bone presentation the head meets the resistance of the whole length of the symphysis pubis.
In posterior parietal bone presentation the head stretches the anterior wall of the lower uterine segment with liability to rupture.
Engagement
It is the passage of the widest transverse diameter of the presenting part, which is the biparietal in vertex presentation, through the pelvic inlet.
The engaged head cannot be easily grasped by the first pelvic grip, but it can be palpated by the second pelvic grip.
Rule of fifths: 2/5 or less of the foetal head is felt abdominally above the symphysis pubis.
Vaginally : the vertex is felt vaginally at or below the level of ischial spines.
Stations
Station 0 the vertex at the level of ischial spines.
Stations -1, 2 and 3 represent 1, 2 and 3 cm respectively above the level of ischial spines.
Stations +1, +2 and +3 represent 1, 2 and 3 cm respectively below the level of ischial spines.
In the primigravida, engagement of the head occurs in the last 3-4 weeks of pregnancy due to the tonicity of the abdominal and uterine muscles.
In the multipara, the head is usually engaged at the onset of labour or even at the beginning of the second stage due to less tonicity.
Causes of non-engagement
Faults in the passenger:
Large head.
Hydrocephalus.
Occipito-posterior positions.
Malpresentations.
Multiple pregnancy.
Placenta praevia.
Short cord.
Polyhydramnios.
Faults in the passages:
Contracted pelvis.
Pelvic tumours.
Full bladder or rectum.
Faults in the power:
Atony of the abdominal muscles.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------What is pre-conceptual care?
A healthy couple generally leads to a healthy pregnancy, and therefore a healthy baby. Attending to a woman's health even before she is pregnant can limit the chances of problems with the health of the subsequent baby. This is particularly important because in the very early weeks of pregnancy the mother may not even know she is pregnant but this is the time when very important stages in the formation of the baby are taking place so it is even more crucial that the risks to the growing baby are reduced to a minimum and there are certain things that a woman can do to achieve this. This is called pre-conceptual care i.e. care of the woman even before she has conceived.
What does pre-conceptual care involve?
Generally pre-conceptual care simply means that a couple should become as healthy as possible and follow certain simple advice that has been found to increase the chances of having a healthy baby. There is nothing complicated about it but the woman may want to talk things over with her doctor before conceiving especially if she has certain health problems of her own. Below are the most important aspects that doctors advise a woman should consider before trying for a baby.
Smoking
Stopping smoking is probably the single most important thing that a woman and her partner can do towards having a healthy baby. Men who smoke tend to have lower sperm counts and the sperm they do produce show high numbers of abnormal sperm, thereby reducing the chances of conception in the first place. Smoking during pregnancy is the main cause of low birthweight babies. Also smoking puts the pregnancy at higher risk of miscarrying or going into premature labour and it is equally important to continue not smoking after the baby has arrived since babies born into a household where there is a smoker are more at risk of cot death, chest infections and asthma.
Folic acid
The vitamin folic acid reduces the chance of a baby being born with spina bifida. Spina bifida is a disability caused by a malformation of the spine and, since the spine is formed very early in pregnancy, occurs in the first few weeks after conception and can result in the baby being born with severe paralysis of part of the body. Spina bifida may be associated with hydrocephalus, when fluid collects near the brain. About 400 babies a year in the UK are born severely disabled by spina bifida but research has shown that folic acid prevents three out of four cases.
Although there are many foods that contain this vitamin (such as vegetables, cereals and beans) the simplest way to supplement the diet to provide a sufficient amount of folic acid to give this beneficial effect is to take a tablet every day. A recent Government recommendation advises all women to commence folic acid at a dosage of 0.4 milligrams (400 micrograms) a day if they are contemplating a pregnancy. They should be taken from the moment the woman begins trying to conceive until the twelfth week of pregnancy.
There is no need for any other vitamin or mineral supplements before or during pregnancy unless the woman is a strict vegan when it is probably advisable for her to take iron and multivitamin supplements. Vegans who wish to take folic acid should seek further advice from their GP as some multivitamins have an excess of recommended daily allowance. A well balanced diet provides all the necessary vitamins and minerals for pregnancy.
Rubella (German measles) immunity
Rubella (also known as German measles) is usually a very mild illness in adults and children, usually involving a slight temperature and a rash and in these situations it is usually harmless. However, if a pregnant woman contracts rubella especially in the early stages of pregnancy it can cause damage to the baby including deafness, blindness and heart defects. Most women will be immune to rubella because they will have been given the rubella vaccine at school. However, some will have missed the vaccine and there are other women who, despite having been given the vaccine, lose immunity as the years go by.
Therefore, it is advisable for a woman to have her rubella immunity checked by her doctor with a simple blood test since, if she is not immune, she can be immunised before she becomes pregnant. If this does happen she will be advised by her doctor not to become pregnant for three months after the immunisation since it is thought that there may be a risk to a baby conceived in the three months following the injection. Leaving the blood test until pregnancy occurs is too late for that pregnancy since, if the mother is found to be not immune, the immunisation cannot be given whilst pregnant. She is at risk if she comes into contact with someone who has illness. Therefore the sensible measure is to have one's rubella immunity checked before becoming pregnant.
Diet
It is easy to become over anxious about diet before and during pregnancy especially since a number of 'scares' in the media a few years ago. Therefore it is worth saying that as long as a woman eats a healthy well balanced diet and tries to maintain a normal weight she is extremely unlikely to develop any problems with her pregnancy. There are one or two foods that are best avoided during pregnancy and in the pre-conceptual period, such as soft or blue-veined cheeses, pate, liver and raw meat.
As far as body weight is concerned it is sensible to try to attain a normal weight for a variety of reasons not least of which is that it could be extremely uncomfortable being overweight and pregnant. Also if any complications arise during pregnancy or labour it is usually much easier for the doctors to deal with these problems if the mother is not overweight. Finally, the risk of developing blood pressure problems in pregnancy is greater if the mother is obese.
Alcohol
There is no need to stop drinking alcohol before a pregnancy or even during pregnancy but heavy drinking is harmful both to the woman and (if she is pregnant) to the unborn child, so it is advisable to restrict alcohol intake to modest amounts and certainly less than fourteen units a week in the pre-conceptual period. (A unit of alcohol is equivalent to half a pint of beer, a glass of wine or a measure of spirits.)
Medication
Those women on regular medication from their doctor should check, before they become pregnant, that their tablets are safe in pregnancy. Most are, but there are one or two which the doctor may wish to change before conception. For instance some blood pressure drugs and most anti-epileptic drugs can affect the foetus. If a woman is trying for a baby it is also sensible to mention this to the doctor if he is prescribing for her since some commonly prescribed drugs are not suitable in pregnancy such as some antibiotics, anti-inflammatory painkillers and some hormone tablets.
Genetic counselling
Couples with a close family history of, or a previous child with, any disorder that is inherited (such as cystic fibrosis or muscular dystrophy) should seek medical advice regarding the chances of a subsequent child having the same disorder. The GP may seek further advice from a specialist in genetic counselling to help such couples to decide whether or not to go ahead with a pregnancy. In some cases, a certain amount of screening of the couple can be done to provide a better estimate of the chances of an affected baby. For some conditions further tests can be done in early pregnancy to enable the couple to decide whether or not to continue with the pregnancy. It is probable that this area will attain increasing significance in terms of screening in the years to come.
Exercise
Regular exercise is recommended in the pre-conceptual period as it is for normal living. Pregnancy and labour are physically demanding and therefore it makes sense to be as fit as possible before becoming pregnant.
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