Need to know - Antenatal care
Obstetrician Professor Mark Kilby answers GP Dr Linden Ruckert’s questions about iron supplements, delaying cord clamping and the best way to pick up pre-eclampsia
Obstetrician Professor Mark Kilby answers GP Dr Linden Ruckert's questions about iron supplements, delaying cord clamping and the best way to pick up pre-eclampsia
- Pregnant women should be offered screening for Down's syndrome with a test that provides the current standard of detection rate above 60% and a false positive rate of less than 5%. Pregaday one to two tablets a day is sufficient treatment in most women with anaemia diagnosed during pregnancy.
- Gestational diabetes and impaired glucose tolerance in pregnancy affect between 3% and 6% of all pregnancies, while evidence suggests a reduced risk of neonatal hypoglycaemia but no other statistically significant difference.
- Automated dipstick urinalysis is more accurate as a screening test for pre-eclampsia than visual dipstick reading.
- Plotting serial symphyseofundal height measurements on individual customised growth charts can improve the detection of fetal growth problems.
- Measuring cervical length by transvaginal scanning can assess the risk of pre-term delivery but not whether it will occur.
- There is some evidence that persistent urinary incontinence is significantly lower in women following Caesarean deliveries.
- In full term neonates, delaying cord clamping for a full 120 seconds at birth produces benefits that extend into infancy.
- Postmortem – even in an apparently normal stillborn baby – can identify unknown anomalies or causes of still birth.
- Damage to the anal sphincter is more common after vaginal delivery than was once thought, with significant rates of faecal soiling in women after childbirth
How evidence based is the current schedule of antenatal care?
It is difficult to answer this precisely. However, the evidence and timing of antenatal care has been reviewed by two recent documents. The first – Antenatal Care: Routine Care for the Healthy Pregnant Woman – was published in October 2003 by a NICE review group in conjunction with the National Collaborating Centre for Women's and Children's Health.
This contains a scheduled programme of antenatal appointments for a ‘low risk' pregnant woman with an uncomplicated medical course.
It lays out the gestational age at which they should come into contact with health care professionals, usually community midwives.
There is a grading system for the recommendations available at http://www.guidance.nice.org.uk.
In 2004 the NSF for children, young people and maternity services was published, which lays out the care for the pregnant woman and her newborn child that should be provided by the NHS.
Are there any good websites that explain screening for chromosomal abnormalities in early pregnancy?
There often seems to be a delay before women are seen in clinics. This means the GP ends up having to do the explaining and it is useful to look at the written data on the integrated tests and other invasive tests such as chorionic villus sampling (CVS) and amniocentesis.
Again in the NICE guidelines on antenatal care, key recommendation four indicates that pregnant women should be offered screening for Down's syndrome with a test that provides the current standard of detection rate above 60% and a false positive rate of less than 5%.
This includes a test performed between 11 and 14 weeks such as the nuchal translucency test as part of a combined serum screening test with free HCG and PAPP-A.
It also discusses the integrated test, which is a nuchal translucency scan, PAPP-A and HCG at 11 to 14 weeks and then a repeat serum screening test between 14 and 20 weeks, including a measurement of alphafetoprotein, unconjugated oestriol and inhibin A.
Obviously there are many websites but most of them are by commercial organisations. The Department of Health website on the Down's syndrome screening programme can be accessed on http://www.screening.nhs.uk/downs/procedures.htm and is extremely helpful both to doctors and patients.
This outlines the biochemical screening test, the ultrasound screening tests including nuchal translucency and the combined serum screening test, along with information of how to interpret results.
It then goes on to discuss follow-on diagnostic procedures like CVS and amniocentesis.
It gives background information on cytogenetic techniques and also information on what is a chromosome and what is Down's syndrome. In addition it gives local contact information.
The WHO definition of anaemia in pregnancy could lead to many women taking iron in the third trimester of pregnancy. Who should be treated and for how long? Is Pregaday enough and does vitamin C make a big difference in iron absorption?
The NICE guidelines on antenatal care in pregnancy indicate that iron supplementation should not be offered routinely to all pregnant women as there is no evidence of any beneficial effect on maternal or fetal outcomes. It may also have unpleasant side-effects.
The same guideline indicates that pregnant women should be offered screening for anaemia during pregnancy and that this should take place in early pregnancy at the first antenatal appointment and then again at 28 weeks.
The WHO definition of anaemia is haemoglobin of 11g/dl and haemoglobin levels outside the normal UK range for pregnancy were stated as 11g/dl at first contact and 10.5g/dl at 28 weeks.
If haemoglobin is below this, iron supplementation should be considered. The Cochrane library review on treatments for iron deficiency anaemia in pregnancy indicate that despite finding 17 trials involving 2,578 women they were small and methodologically poor.
All iron medication in pregnancy showed a reduction in the incidence of anaemia but it was not possible to assess the effects of treatment by severity of anaemia.
A link was found between the dose of iron prescribed and the reported adverse effects, but most of the trials had no assessment of relevant clinical outcomes and there was a paucity of data on adverse effects.
Although trials that looked at iron administered by intramuscular or intravenous routes appeared to produce better haematological indices in women than those treated orally, no clinical outcome data was available.
So my view is that one or two Pregaday tablets a day is sufficient treatment in most pregnant women with anaemia diagnosed during pregnancy.
It is my practice to repeat their haemoglobin a month after starting therapy and in those women that are resistant to treatment consider investigating the patient further for rarer causes of anaemia.
There is evidence that vitamin C aids iron absorption but the majority of UK women are not vitamin C deficient.
However it would do no harm to give women information about taking natural vitamin C in their diet while taking iron supplementation during pregnancy.
Do different hospitals manage gestational diabetes differentially? How should these women be managed in future pregnancies and what are their long-term risks of diabetes?
Gestational diabetes and impaired glucose tolerance affect between 3% and 6% of all pregnancies and there has been much debate recently on management – mainly fuelled by a lack of conclusive evidence on associated pregnancy complications.
The Cochrane library last reviewed treatments for gestational diabetes and IGT in pregnancy in April 2003. This review looked at randomised controlled trials comparing alternative management strategies for women with gestational diabetes and impaired glucose tolerance in pregnancy.
Three studies were included – with a total of 223 women – all with impaired glucose tolerance alone. But there were insufficient figures for any reliable conclusions to be drawn about the effect of treatments on perinatal outcome.
The differences in abdominal operative delivery rates and admission of babies to special care units were not statistically significant and a reduction in birthweight of greater than the 90th centile was found not to be significant.
The reviewers concluded that an interventionist policy of treatment may be associated with a reduced risk of neonatal hypoglycaemia but no other statistically significant difference was detected – with the caveat: ‘the number of trials included was small and the number of outcomes was only reported by one study, resulting in a very small sample size and wide confidence intervals'.
What is the best way to pick up pre-eclampsia? Is home dipsticking of urine effective? Is there good evidence that antenatal care is effective in picking up pre-eclampsia and what could we do better both in general practice and in hospitals? Are Dopplers of the placental bloodflow useful?
Again in the NICE antenatal care guidelines it is indicated that at first contact with a pregnant woman the level of risk of developing pre-eclampsia should be evaluated.
It is noted that the likelihood of developing pre-eclampsia during a pregnancy is increased in women who:
• are nulliparous
• are 40 or older
• have a family history of pre-eclampsia
• have a history of previous pre-eclampsia
• have a BMI of 35 or more at first contact
• have a multiple pregnancy or pre-existing vascular disease.
The guidelines emphasise that blood pressure should be measured on standardised equipment and whenever a blood pressure is measured in pregnancy, a urine sample should also be tested for proteinuria.
There is little doubt that measuring systolic and diastolic blood pressure during pregnancy is an effective way of detecting hypertension – that is a diastolic blood pressure of 90 mmHg or more.
The diagnosis of pre-eclampsia is made when there is associated significant proteinuria in addition to hypertension of >300mg in 24 hours.
Automated dipstick urinalysis is a more accurate way of detecting proteinuria than visual testing. And albumin creatinine ratio testing can offer a significant improvement over conventional urinalysis because dipstick testing alone is prone to false positives.
Factors affecting the results include reader error – which can be minimised by training and the use of automated monitors – and concentration error – prevented by use of protein or albumin creatinine ratio test.
The use of colour flow insonation of the maternal uterine arteries with Doppler waveform analysis performed at 23 weeks has been used to identify pregnancies at risk of pre-eclampsia and also abnormal placentation.
Recent data has indicated that pre-eclampsia may be predicted with high sensitivity and specificity using increased mean PI and maternal risk factors.
6 Is there really any value in measuring symphyseal fundal height and regular weighing? Similarly, with serial ultrasound scans, what is the best way to detect small-for-dates babies?
Intrauterine growth restriction affects between 6% and 8% of all pregnancies and is associated with significant increase in perinatal mortality and morbidity.
The challenge to identify babies antenatally who are not growing appropriately is therefore fundamental.
There is evidence that plotting serial symphyseofundal height measurements on individual customised growth charts can improve the detection of fetal growth problems by reducing unnecessary referrals for investigations.
Customised antenatal growth charts are now recommended by the Royal College of Obstetricians and Gynaecologists guidelines and serial fundal height measurements are recommended by NICE.
The key to using these is as part of a maternal customised growth chart so that maternal BMI and previous birthweights of babies can be included in the algorithm that decides whether the measurement symphyseofundal height is appropriate for gestation or not.
There is no doubt that serial ultrasound examinations would detect small for gestational age babies but these would be very resource intensive and are not cost effective.
There is also little evidence to inform the interval between scans and whether this would make a difference in terms of detecting intrauterine growth restriction.
Are there any useful tests to predict premature rupture of membranes? What is the connection with bacterial vaginosis and the place of the sutures?
There are a number of commercial tests that will confirm pre-labour ruptured membranes but very few that will predict it.
The measurement of cervical length by transvaginal scanning gives a significant and sensitive risk allocation for the likelihood of pre-term delivery but not whether amniorrhexis will occur independently of this.
BV may be associated with pre-term delivery and there has been a lot of research on choice of antibiotics to prevent this but results have been mixed, with some studies suggesting antibiotics may be harmful for the baby.
There is certainly no evidence that cervical cerclage will reduce the risks of pregnancy loss in women with bacterial vaginosis.
What are your views on true elective Caesarean section? Does it really preserve the pelvic floor and how much of the damage is due to hormones and pregnancy itself? Are we reaching a point where skills in vaginal breech and twin delivery will not be maintained so there will be no other option? And is there good evidence that we should do elective lower segment Caesarian section (LCSC) in these cases?
Caesarean section carries risk of maternal morbidity and mortality and it is always safer to have an uncomplicated vaginal delivery than an operative delivery.
However, with modern anaesthetics, antibiotic prophylaxis and thromboprophylaxis, elective Caesarean section carries significantly less maternal morbidity and mortality than an emergency Caesarean section.
There is some evidence from longitudinal studies of pregnant women that persistent urinary incontinence is significantly lower following Caesarean deliveries than other vaginal births.
This is also the case for other forms of incontinence – including faecal incontinence – but there have been no prospective studies showing that urinary morbidity could be completely attenuated by Caesarean section.
As I said, there is also a balance between serious life-threatening morbidity such as bleeding, infection and thromboembolic disease and morbidity such as urinary incontinence.
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Should the third stage not be managed actively as routine to prevent anaemia in infants? I've read something recently about delaying clamping the cord but some say even ?WOT?synto with ant shoulder ?? should not be done routinely.
Postpartum haemorrhage is a significant cause of maternal morbidity and mortality worldwide. The active management of the third stage to delivery the placenta – usually by maternal administration of syntocinon – is therefore prudent.
But there has been recent evidence suggesting improved perinatal outcome when ‘delayed clamping' of the umbilical cord is performed both in premature and term babies.
In preterm neonates, delaying cord clamping by between 30 and 120 seconds, rather than early cord clamping, is associated with reduced need for transfusion and less risk of intraventricular haemorrhage.
In full-term neonates, delaying cord clamping for a full 120 seconds following birth demonstrates benefits that extend into infancy. These include an improved haemoglobin and ferritin concentration with a clinically important reduction in the risk of anaemia.
What are the minimum investigations when a woman has an unexplained stillbirth? How do you advise her about a future pregnancy?
Probably the two most useful ‘examinations' after an unexplained stillbirth are a full postmortem of the fetus and placenta and to plot the baby's weight on customised growth charts.
Most of the published evidence indicates that a postmortem – even in an apparently normal baby – will identify unknown anomalies or causes of death.
Macroscopic and histologic examination of the placenta and membranes will also yield useful information.
In addition, there is increasing evidence that a sizeable proportion of ‘unexplained stillbirths' can be re-classified as fetal growth restriction if customised growth birthweight charts are used and the placenta examined.
Other tests such as maternal serology excluding viral, bacterial and parasitic infection, lupus anticoagulant/anticardiolipin antibodies and in some cases parental karyotype may be useful.
Pain over sutures and anal sphincter problems seem to be quite common postpartum if you ask. How quickly should scar pain be referred and is anal damage more common than previously thought?
It is increasingly being noted that the physiological changes occuring in pregnancy take much longer to return to normal than once believed – up to 20 weeks.
After Caesarean section or episiotomy, it is not uncommon for patients to have discomfort but I am often amazed by the number of patients who have a rapid resolution. But a patient should be referred for review if she has pain for longer than eight to 12 weeks.
The use of transrectal ultrasound has found that asymptomatic and symptomatic damage to the anal sphincters is much more prevalent after a vaginal delivery that was once thought.
This was confirmed by a prospective follow-up series of women monitored for six years after giving birth, which showed significant rates of faecal soiling. Many women suffer and do not seek help from healthcare professionals. It is therefore vital that women are made aware of this possibility and seek help early.
Professor Mark Kilby is Dame Hilda Professor of Maternal and Fetal Medicine at the Birmingham's Women's Hospital.
What I will do now
Dr Ruckert reflects on the answers to her questions
I will feel more comfortable using Pregaday rather than larger doses of iron, which add to the constipation of later pregnancy. Patients and GPs are often perplexed by the different ways of managing gestational diabetes and the lack of evidence explains why hospital protocols differ.
I have never seen a customised individual growth chart but have seen a lot of women made anxious by being told that the fundal height suggests the fetus is small for dates – and then giving birth to a normal-sized baby. I will try to find out more about them to see if patients can be assessed more accurately.
It is my impression that anal problems are common post partum but are not volunteered, so I will continue to ask about them.
With anaemia in small children being so common it makes sense to listen to the evidence and support women who request delayed clamping of the cord in their birth plans.
Dr Linden Ruckert is a GP in north LondonIntra-uterine growth restriction affects 6-8% of pregnant women Antenatal care