Booking, Screening & Antenatal Care

Original article by Tom Leach | Last updated on 28/6/2014
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Introduction

  • Much of the follow-up of pregnant women is carried out in the community, by midwifes at primary health care centres. The risk of death from pregnancy in the UK is roughly 1 in 20 000.
  • Antenatal care is as much about educating women about pregnancy, childbirth and child care, as it is about providing for actual medical needs, particularly in the case of a first pregnancy.
  • The exact measures will differ between NHS trusts, but below is a general outline of the type of care provided in pregnancy.
 

Planning

The aim of pre-pregnancy planning is to create the conditions most likely to result in a healthy pregnancy.
General advice
Diet

The recommended diet is well-balanced, with plenty of fresh fruit and vegetables, starchy carbohydrates (e.g. bread, pasta, rice), dairy products and protein (including oily fish 2x per week, eggs and lentils).
Foods to avoid:

  • Unpasteurised milk, soft cheese (and cheese with mould) , pate – can contain Listeria monocytogenes which may only cause a slight fu-like illness in the mother, but can result in miscarriage and still-births
  • Undercooked meat, (contact with cat litter) – can result in the contraction of Toxoplasmosis which can cause neurological defects
    • Salmonella is not known to cause any long term effects
  • Vitamin A – see below
  • Tuna – is ok is small amounts (<4 tins per week), but it contains a lot of mercury which is teratogenic.
  • Too much fish – although fish is recommended, you should have no more than two portions per week – as many fish can contain pollutants, and eating too mcuh can concentrate these molecules. Some sea foods are not risky, notably – shellfish and prawns.

General advice on food preparation – wash all foods thoroughly, and cook all meat thoroughly, including cooking ready-prepared chilled meat.

Supplements

  • FOLIC ACID – which should be taken when planning pregnancy, and for the first 13 weeks after conception (400 mcrogram/day). It prevents NTD’s and cleft lip and palate.
  • Vitamin A can impair folic acid absorption – and the two should not be taken in a combined supplement. High levels can also cause birth defects. Avoid too much vitamin A – check supplements, and avoid fish liver oil, avoid eating liver.  Max 700mg/day.
  • Previous NTD babies / diabetic mothers / mothers on antiepileptcis / mothers in whom administration does not begin until after conception – mothers should take 5milligrams of folic acid per day
  • VITAMIN D supplements are also recommended (10mcrogram/day)
  • Many pregnant women also become iron deficient – thus recommending foods high in iron (e.g. read meat, breakfast cereals (fortified) green veg, bread (fortified).
    • Vitamin C can help the absorption of iron
    • Tea and coffee impair iron absorption and should be avoided at meal times
    • Iron supplements are not recommended for all pregnant women, as they can cause side effects (notably constipation), but many women do take them, either self-prescribing or through a clinician.
    • Women ARE encouraged to take iron in the run up to delivery to negate blood loss, and reduce maternal morbidity.
  • Free vitamin supplements are available to some women from deprived backgrounds. Consider offering on booking visit.

Alcohol

Alcohol can easily cross the placenta. The official government advice is to avoid alcohol if possible, and not to exceed 2U, no more than twice per week. Prolonged and excessive alcohol intake can result in fetal alcohol syndrome – where the child suffers from intellectual and behavioural problems later in life.

  • Binge drinking >5U/per session– is particularly harmful

Caffeine

Excess caffeine should be avoided, but you don’t have to cut out caffeine completely. Excess caffeine is associated with low birth weight. The max recommended is 200mg / day (roughly equal to 1 bar of chocolate and 1 cup of instant coffee, or two cups of instant coffee, or two cups of tea. Filter coffee has up to 150mg per cup).

Peanuts

There is not clear evidence as to whether eating peanuts in pregnancy or during breastfeeding alters the risk of allergy at all. Previous advice was to avoid peanuts.

Smoking

In approximately 25% of pregnancies, the mother is a smoker. Smoking increases the risk of:

  • Placental abruption
  • Perinatal mortality
  • Preterm delivery
  • Premature rupture of membranes
  • Placenta praevia
  • Low birthweight
  • Risk of miscarriage is doubled
  • Reduction in the child’s reading age (under the age of 11)
  • In women who do not want to or are unable to stop smoking, there are still benefits to a reduction in the number of cigarettes of smoked, as this decreases the amount of nicotine that crosses the placenta, and increases birthweight.
  • Only about 17% of smokers will stop during pregnancy.
 

Other Advice

Reduce weight if obese – it is important to emphasise the benefits of doing this before attempting pregnancy. If obese at booking, thromboprophylaxis may be advisable. Weight loss during pregnancy should not be advised – it increases the risks of a small baby (which itself is a RF for obesity later in the child’s life) and increases the risks of post-natal problems.
Control diabetes advise patients that HbA1C should be <6.1
Control other conditions

  • Hypothyroidismis particularly important. The fetus doesn’t produce endogenous thyroxine until it is 12 weeks old, and a lack can result in neurological defects

Check all medications – for teratogenic effects. Common examples include:

  • Paroxetine – SSRIfetal heart defects (particularly in first trimester)
  • Lithium Mood stabiliser – used mainly in bipolar disorderalso associated with heart defects (Ebstein’s abnormality – tricuspid valve leaflets stuck to walls ofventricle)
  • Warfarin
  • Retinoids – structurally similar to vitamin A

Counselling

  • E.g. if known to be at high risk of birth defects (e.g. sickle cell disease) then counselling should be advised as to the possibly outcomes, tests and options (e.g. termination)
  • Always remember, when advising for a test, always make sure that the patient understands what the results will mean, and, the implications of positive and negative results.

Recreational drugs have serious implications for development and should be avoided
Exercise and sex – are not associated with altered outcomes. Contact sports and scuba diving (decompression) should be avoided. Mild exercise should be encouraged
Work –some types of employment are associated with poorer outcomes. For example a job that involves prolonged periods of standing can increase the risk of prematurity, hypertension and pre-eclampsia.

 

Maternity leave in the UK

Women in the UK are entitle to statutory maternity leave of 52 weeks, if:

  • They have been employed for 26 weeks by the same employer before they give notice of their maternity
  • They earn >£95/week (roughly equal to >2 ½ full days per week on min. wage)

Statutory Maternity pay (SMP) is usually available for 39 weeks. Many employers offer their own benefits above this legal guarantee. The amount paid is:

  • 90% of your wage for the first 6 weeks
  • 90% of your wage, or about £125 (whichever is lower) for 33 weeks
  • You should give 15 weeks’ notice – but the exact date can be changed with 28 days notice
  • Maternity leave can begin from 11 weeks before the due date
  • Compulsory Maternity leave – you don’t have to take all the 52 weeks, but you do have to take:
    • 2 weeks after the baby is born (most jobs)
    • 4 weeks after the birth if you work in a factory

Problems with the pregnancyyou can still take the statutory maternity leave if:

  • Your child is stillborn after 24 weeks gestation
  • Your child is a live-birth at any age, but subsequently dies

Working during Maternity leave – you can work for up to 10 days during maternity leave to help keep up to date with your job skills. If you work more than this, you lose your maternity pay for the week in which you worked.

 

Spontaneous miscarriage

  • Occurs in about 9% of women aged 20-40.
  • Occurs in 75% of women >45
  • It is not significant unless a woman has 3 or more
  • If a woman has had 3 or more miscarriages, the risk of another is 45% (nullips under 35), or 35% for parous women.
 

Obesity in pregnancy

Defined as a BMI >30 at booking
Increased risks in pregnancy:
  • Spontaneousfirst trimester miscarriage
  • Recurrent miscarriage
  • Pre-eclampsia
  • Gestational Diabetes
  • Thromboembolism
  • Cardiac disease
  • Induced labour
  • Caesarian
  • Infection
  • PPH
  • Maternal mortality
  • Lower rate of breast-feeding
  • Fetal risks
    • Prematurity
    • Abnormality
    • Still birth
    • Neonatal death
 

Normal weight gain during pregnancy

Maternal BMI
Recommended weight gain in pregnancy
<19.8
12.5 – 18 Kg
19.8 – 26
11.5 – 16 Kg
26.1 – 29.0
7 – 11.5 Kg
>29
~6 Kg
 

Timetable

The number of appointments is determined by the individual hospital trust. Recommendations are:
  • 10 for nulliparus women
  • 7 for parus women
  • More for those with diabetes
At all appointments
  • BP and urine dipstick for ketones and glucose – for pre-eclampsia
  • Offer the patient to ask about any questions and concerns
  • Ask about any special arrangements for the birth – e.g. who would she like to be present, home birth, etc
  • For most normal pregnancies, standard appointments are in the community, usually with the midwife
Time
Care
Booking
-          Should be before 12 weeks gestation
-          Sometimes spread over two appointments due to the volume of information
 
Blood sample – voluntary screening for HIV, hep B, rubella, syphilis, anaemia
  • Identification of hep B and subsequent Ig vaccine for the baby reduces transmission by 95%
  • HIV transmission is about 25%. With antiretroviral treatment + C-section, + avoidance of breastfeeding, this is reduced to 1%
  • Syphilis is associated with stillbirth, neonatal death and preterm delivery
  • Rubella essentially finds out if the mother is immune or not. If she is not she can be offered the vaccine after birth, to avoid any risk of contracting the condition in future pregnancies. The vaccine itself cannot be given during pregnancy as it is teratogenic.
 
Additional screening
  • Thrombophylia if FH or personal Hx
  • Previous mental illness?
  • Current medications – eg. Stop warfarin (swap for LMWH) and anti-psychotics!
 
Offer advice – the stuff detailed above!
 
Urine sample and BP. Should be tested for:
  • Glucose
  • Asymptomatic bacteraemia – which is present in 2-5% of women, and can cause preterm labour and pyelonephritis.
  • Ketones
 
There is not routine screening for gestational diabetes
  • Offer 75g GTT at 18 and 28 weeks if previous gestational diabetes
  • Offer 75g GTT at 24 weeks if BMI >30, 1st degree relative with diabetes, or previous pregnancy >4.5Kg, or if from area of high diabetic prevalence (Indian subcontinent, Black Carribean, Middle Eastern)
 
Other options
  • Mother offered optional scan for dates between 10-13 weeks
  • Consider CXR at 14 weeks if TB risk (e.g. 1st degree relatives or patient from area of high prevalence)
  • Consider offering free vitamin supplements if from dpreived background
16 weeks
  • Review previous test results
  • Offer iron to all women with Hb <11g/dl
  • Offer treatments for other conditions if necessary
  • Urine and BP
18-20 weeks
Scan for fetal structural abnormalities
  • In placenta praevia, where the placenta covers the os, further scan should be offered for 36 weeks
  • Urine and BP
25 weeks
Nulliparus women only
  • Urine and BP
  • Measure and plot symphasis pubis height
28 weeks
  • Urine and BP
  • Measure and plot symphasis pubis height
  • Blood group / antibody screen
  • Offer anti-D prophylaxis for rhesus negative women
  • Offer treatment of anaemia if Hb <10.5
31 weeks
Nulliparus women only
  • Urine and BP
  • Measure and plot symphasis pubis height
  • Review of results from 28 weeks – offer care where appropriate
36 weeks
 
  • Urine and BP
  • Measure and plot symphasis pubis height
  • Offer external cephalic version (ECV) to all breech women
  • Consider review of placenta praevia
38 Weeks
  • Urine and BP
  • Measure and plot symphasis pubis height
40 Weeks
  • Urine and BP
  • Measure and plot symphasis pubis height
41 Weeks
  • Urine and BP
  • Measure and plot symphasis pubis height
  • Offer membrane sweep and induction of labour

Screening for Down’s syndrome

  • False positive rate – <3%
  • Sensitivity – 75%
All women are offered screening for Down’s Syndrome.
  • Those with a positive test result are offered a termination of pregnancy
 
Identifying those at risk- Screening

Offered to all pregnant women
Ideally should be performed by the end of the 14th week of gestation (this is the latest time you can perform nuchal transparency), and womend presenting later will have to undergo a different type of testing (see below).
A formula, using a combination of the woman’s age, blood test, and USS scan are used to determine the risk for an individual mother.
There are several methods of doing this:
The combined test – this is for women who present in the first trimester and is the most widely used type of Down’s screening in the UK. Recommended by NICE. It uses:

  • Nuchal translucency – from the USS. Needs to be performed betwwne 11 weeks 0 days and 13 weeks 6 days. Increased nuchal transparency is strongly associated with heart effects, especially those caused by chromosomal abnormalities. The greater the transparency, the greater the risk of abnormality.
  • Beta-HCG – from the blood
  • PrAP – (Pregnancy associated plasma protein) – from the blood
  • The mothers age
  • And it calculates a risk of Down’s, given as a 1 in XXXX figure
  • If the risk is greater than 1 in 250 – then the woman is offered further screening.
  • It will also detect many other anueoploidies (95% of all cases)

The quadruple test – can only be done between 15 weeks 0 days, and 20 weeks 0 days – i.e. – in the second trimester. Looks at:

  • Alpha FP
  • Unconjugated estradiol
  • BetaHCG
  • Inhibin A – not widely available in the UK
  • Woman’s age
  • The test is not widely used in the UK, but can be useful for pregnancies presenting in the second trimester.

The integrated test – combines the quadruple test with nuchal transparency + PrAP (both performed in the first trimester). More accurate than the ripple test, but the woman will have to wait for results. Women also have to attend clinic twice (once in first trimester, once in second trimester) – and 25% of women fail to attend the second time around.

 
Counselling for the initial test
  • Women should understand that the value calculated is only a risk. Even those with a low risk score could still have a Down’s baby. Those with a high risk score can still have a normal baby.
    • If the mother would not consider termination, even if the baby had Down’s, then consider if the test is actually any use
  • Remember, it can cause a lot of anxiety in a lot of normal pregnancies!
    • The vast majority of those with a positive combined test will have a NORMAL pregnancy
 
If the results are positive
Women will be offered chorionic villus sampling or amniocentesis (depending on the date of gestation), as a diagnostic test. CVS is about 97% accurate.

Chorionic villus sampling – if 10-13 weeks gestation

  • In this procedure, a sample of the placenta is obtained, either by USS guided needle through the abdominal wall, or transvaginally.
  • Complications
    • Miscarriage rate = 1-2%
    • Amniotic fluid leakage (<1%)
    • Sepsis (rare)
  • Should not be performed before 10 weeks due to increased incidence of limb deficiencies
  • Accuracy – diagnosis can be made in about 97% of cases
  • Transabdominal procedure is easier, and yields better results than transvaginal

Amniocentesis – if >15 weeks gestation

  • In this procedure, a needle is passed, usually under USS guidance, into the amniotic fluid, and roughly 10-20ml of fluid is aspirated (1ml for every week of gestation)
  • Contains samples from fetal skin, urinary tract and lungs
  • Rhesus prophylaxis should be considered
  • Complications
  • Miscarriage rate = 0.5-1%
  • Amniotic fluid leakage – 3%
  • Uterine bleeding – 2%
  •  Maternal rhesus sensitisation
  • Sepsis (rare)
  • If amniocentesis is performed in the first trimester, miscarriage risk is 5% - hence the use of CVS in this period
  • Diagnosis is quicker in CVS than in amniocentesis, but CVS is slightly less accurate
  • Amniocentesis is safer than CVS – but can only be safely performed in the second trimester
  • Cell culture in amniocentesis takes 3 weeks – thus any future termination date may be late! Results obtained sooner in CVS.