Medical disease during pregnancy
Hypertensive disorders
Pre-eclampsia
- BP >140/90 mmHg (on two occasions) and proteinuria >0.5g/24h
- Occurs in second half of pregnancy
- Pathology can be split into two stages. Stage 1 – incomplete invasion of the spiral arteries by trophoblasts preventing vasodilation. This results in decreased uteroplacental blood flow. In stage 2 the disease is manifested, the ischaemic placenta possibly via an exaggerated maternal inflammatory response induces widespread endothelial damage, increased vascular permeability and clotting dysfunction
- Hypertension normally precedes proteinuria
- Associated with oedema
- More common in nulliparous women unless they have a history or pre-eclampsia in earlier pregnancy
- More common with age extremes
- May present with headache, visual disturbances, nausea/vomiting, epigastic pain.
- On examination hyper reflexes and ankle clonus may be found
Maternal Complications
- Eclampsia is a grand-mal seizure – treat with magnesium sulphate
- Cerebrovascular haemorrhage
- HELLP syndrome, haemolysis, elevated liver enzymes and low platelet count
- Renal failure
- Pulmonary oedema due to fluid overload
Fetal Complications
- IUGR
- Placental abruption
- Hypoxia
Prevention
- Low dose asprin and Vit C and E supplements may reduce risk in high risk women
Management
- Drugs – antihypertensives given e.g. methyldopa or labetolol if BP gets very high. Aim to get BP to160/100
- Only way to properly resolve the problem is to deliver baby.
- May require induction
- If before 34 weeks, give mother steroids to promote fetal lung maturation
- Requires continuous monitoring of baby
Pre-existing hypertension
- Diagnosed when BP exceed 140/90 before 20 weeks
- Either those with pre-existing hypertension or those that develop it early
- Those with transient hypertension during pregnancy or predisposed to experience it later in life
- More common in older or obese women
- Mostly ‘essential’ but can be secondary due to diabetes or renal disease
- Pre-eclampia more common
- Treat BP and consider pregnancy high risk
Diabetes and gestational diabetes
- Increased insulin resistance during pregnancy due to the insulin antagonistic effects of human placental lactogen and cortisol
- 1-2% of pregnant women develop gestational diabetes
- Risk factors include
- Obesity
- Family history
- Previous baby >4.5kg
- Previous unexplained stillborn
- Previous congenital abnormality
- Diabetes is defined as a fasting blood glucose >7.8mmol/L or a level of >11.1 postprandial (75g oral glucose challenge)
Fetal complications
- Increased risk of miscarriage
- Congenital abnormality – cardiac, renal and neural tube defects
- Fetal macrosomia – shoulder dystocia and hypoxia
- IUGR associated with microvascular diabetic complications
- Jaundice due to hyperbilirubinaemia due to neonatal polycythaemia
Maternal complications
- Pre-eclampsia
- Insulin requirement may rise
- Hyper/hypoglycaemia
- Increased UTI
- At greater risk of instrumental or caesarean delivery
- Increased diabetic disease – nephropathy, retinopathy
Management
- Close monitoring and control of diabetes
- Monitoring fetus
- May be at increased risk of C-section due to macrosomia
- Problem with preterm labour and tocolytics such as salbutamol are diabetogenic and steroids which might be given for prematurity can destable diabetic control
Heart Disease
-
Mostly due to congenital heart disease
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Both blood volume and cardiac output increase by 40%. Output achieved by an increase in stroke volume and a rise in heart rate of 12-15 bpm
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With valvular disease the problem can be that of anticoagulation as warfarin is teratogenic and can cause fetal bleeding and transfer to heparin can be difficult
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In AF digoxin can be given but anticoagulation must be considered
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Women may also develop heart failure during pregnancy. Management is as for pre existing heart failure
Management
- Examination for clinical signs of heart failure
- Echocardiogram
- Drug therapy may include diuretics, vasodilators and digoxin
- Dysrhythmias may require correction
- Fetal ultrasound and CTG
- Premature delivery might be considered if there are signs of fetal compromise
- During labour an epidural can be recommended to minimise pain related stress (possible complications of maternal hypotension)
- Prophylactic antibiotic should be given if a women has a structural heart defect reducing the risk of infective endocarditis
- Avoid supine position
- Second stage of delivery should be kept relatively short – forceps or ventouse
- C-section is associated with haemorrhage, thrombosis and infection – not well tolerated in women with cardiac failure
- Active management of the third stage with syntocinon on its own as ergometrine may be associated with vasoconstriction, hypertension and heart failure
Maternal risks
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Mortality rare but more likely when pulmonary blood flow is restricted (pulmonary hypertension, mitral stenosis)
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Mortality may also be caused by aortic dissection, ischaemic heart disease and cardiomyopathy
Fetal risks
- Growth restriction
- Preterm delivery
Thyroid Disease
- During pregnancy the amount of thyroid binding globulin produced by the liver is increased due to oestrogen stimulation
- There are therefore increased levels of total T3 and T4 but no change in the amount of free circulating thyroid hormone
- Untreated thyroid disease is rare as it generally results in anovulation
Maternal hyperthyroidism
- Occurs in 1 in 500 pregnancies
- 90% are secondary to Grave’s disease
- Less common causes are:
- Toxic nodules
- Hashimoto’s thyroiditis
- Multinodular goitre
- Trophoblastic disease
- Maternal complications of uncontrolled maternal hyperthyroidism are
- Cardiac arrhythmias (e.g. AF)
- Diarrhoea
- Vomiting
- Abdo pains
- Psychosis
- If the underlying cause is autoimmune, thyroid-stimulating antibodies can cross the placenta and cause fetal thyrotoxicosis and goitre
- Main complications for the fetus are:
- Fetal growth restriction
- Still-birth
- Fetal tachycardia
- Premature delivery
- Treatment
- Radioactive iodine is contraindicated because it obliterates the fetal thyroid gland
- Medically with carbimazole or propylthiouracil (lowest dose possible as it can cross the placenta)
- Surgical treatment may be necessary if unresponsive to medical treatment
Maternal Hypothyroidism
- Commonest cause world wide is iodine deficiency (associated with cretinism in the newborn)
- Most common reason in the
UK is Hashimoto’s thyroiditis, followed by treated hyperthyroidism - Women diagnosed with hypothyroidism prior to pregnancy should continue on full thyroid replacement throughout pregnancy.
- Post partum thyroiditis may present with thyrotoxicosis or hypothyroidism but most commonly with postnatal depression 4-6 months following delivery
- Mostly self-limiting but can predispose to permanent hypothyroidism or a recurrence in a following pregnancy
Respiratory disease
Asthma
Haematological Abnormalities
Anaemia
- The 40% increase in blood vol during pregnancy is relatively greater than the increase in red cell mass making women more prone to anaemia
- Anaemia is defined by the WHO as being less than 11g/dL and in pregnancy the lower limit is generally considered as 10.4g/dL
Iron deficiency
- Iron demand doubles from 2mg to 4mg daily during pregnancy
- Diagnosed as a microcytic anaemia
- Treatment is with iron supplementation (60mg daily) – side effects of nausea and constipation
Folate deficiency
- Rare in
UK - Generally diagnosed as a macrocytic anaemia
- Vit B12 and alcohol consumption can also cause macrocytic anaemia
Sickle-cell disease
- Homozygotes experience maternal complications such as increased crises, pre-eclampsia, thrombosis and infection. Fetal complications are miscarriage, IUGR, preterm labour and death
- Regular blood transfusions may be required and hydration (to prevent crises).
- Folic acid supplements are given but iron is avoided
- Heterozygotes generally have no problems but may develop ‘crises’ under extreme conditions
Thalassaemia
- Termed alpha or beta depending on which haemoglobin change is affected
- In alpha thalassaemia the individual is generally very anaemic but this doesnt generally result in obstetric complications unless the they develop severe blood loss
- Partner should be screened, if both parents carry gene, child has a 1 in 4 chance of developing alpha thalassaemia major which is incompatible with life
- In beta thalassaemia women with also be anaemic and be offered iron and folate supplements
- Partner should also be screened again. Beta thalassaemia major results in severe anaemia in children, requiring blood transfusions. This can result in iron overload and death
Renal Disease
- In pregnancy GFR increases by 40%
- This is associated with reduced serum levels of urea and creatine
- Kidneys also increase in size and the collecting systems dilate
- This puts patient at increased risk of UTI and pyelonephritis
- Urine infection is associated with preterm labour, anaemia, increased perinatal mortality and morbidity
Chronic renal disease
- Complications depend on the degree of renal compromise
- Mother has increased risk of pre-eclampsia which can be difficult to diagnose in the background or proteinurea and hypertension
- Also associated with IUGR and preterm labour
- Renal function and BP must be monitored as must fetal growth and development
- Women on dialysis have impaired fertility and conception is not common.
- When it does occur it has a very high rate of miscarriage and termination is often offered
- When pregnancy does occur it is associated with pre-eclampsia, hypertension and volume overload
Epilepsy
- Mostly diagnosed before pregnancy and pregnancy has no effect on disease
- Seizures are particularly likely around the time of labour due to hyperventilation, dehydration and exhaustion
- Main concern is the possible teratogenicity of drugs used to treat epilepsy
- Possible fetal defects are;
- Cleft lip and palate
- Neural tube defects
- Congenital heart defects
- Haemorrhagic disease of the newborn
- The rate of abnormality of 6% in women receiving treatment, 4% for those not receiving treatment and 3% for non-epileptic women
- Therefore epileptic women should take higher doses of folic acid before and during their pregnancy
- The teratogenic effect of drug therapy is cumulative
- Control of seizures in pregnancy can deteriorate with reduced compliance and differences in drug handling by the body
- Anticonvulsants affect hepatic handling of Vit K making the baby more prone to haemolytic disease of the newborn. Mother should therefore receive Vit K supplements towards the end of pregnancy and the baby should have Vit K at birth
- Post partum women should be encouraged to breast feed unless they are on phenobarbitone which causes sedation of the baby and subsequent feeding difficulties
Venous thromboembolitic disease
Leading cause of maternal death in the UK
Pregnancy is prothrombotic and the incidence of venous thrombosis rises 6 fold
There is reduced venous flow from the legs, increased coagulation factors such as fibrinogen, factor VIII and von Willebrand factor and suppressed fibrolysis
- Women with inherited prothrombotic conditions such as Factor V Leiden deficiency are particularly prone
- Managed with ultrasound or venogram assessment of the DVT
- Ventilation-perfusion scanning should be done if PE is suspected
- Patient should be treated with heparin
- Problem with warfarin in that it freely crosses the placenta and is associated with fetal abnormality and haemorrhage
- With long term use of heparin there is a risk of oestopaenia, heparin induced thrombocytopenia and heparin allergy
- Neither heparin or warfarin cross into breast milk