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Pregnancy and Medical Disease Counselling

Introduction

 

The majority of pregnancies are not complicated by underlying disease; however, there are a number of conditions that can affect both mother and unborn baby. Care for these women is important both before conception and throughout their pregnancy in order manage the risks to ensure they remain as low as possible. When women with underlying conditions become pregnant they are often seen in a joint clinic with an obstetrian and a specialist physician.

 

There are a vast array of diseases that can complicate a pregnancy and include heart disease, hypertension, diabetes, epilepsy, thyroid disease and asthma (amongst many others).

 

This article will discuss some of the more prevalent conditions that affect pregnancy (noted above) but will focus particularly on diabetes, epilepsy and heart disease, because of their clinical importance.

 

Diabetes

Table to Show the Risks of Diabetes in Pregnancy

Management of diabetes in pregnancy

Management of diabetes in pregnancy:

 

N.B: Neonates born to diabetic mothers are usually kept on the Special Care Baby Unit for 24-48 hours in order to monitor for hypoglycaemia. 

 

Epilepsy

 

Epilepsy affects 0.5-1% of women of child-bearing age. The main challenge with epilepsy in pregnancy is weighing up the risk of continuing anti-epileptic medication (many of which are teratogenic) versus the consequences of stopping the medication and the threat of increased fits (which may result maternal and fetal hypoxia). It is generally considered that uncontrolled seizures are more harmful to the fetus than the potential teratogenic effects of anti-epileptic medication (about 2% risk).

 

Pre-pregnancy counselling is important to convey this to the patient but ultimately, it is the patient’s decision.

 

Table to Show Potential Effects of Anti-Epileptic Medications

Table to Show the Potential teratogenic effects of anti-epileptic medications:

 

Other pregnancy complications that have been associated with epilepsy include:

-          Antepartum haemorrhage

-          Post-partum haemorrhage

-          Pre-eclampsia

-          Pre-term delivery

-          Low birth weight

-          Fetal risk of epilepsy (3%)

 

Management of epilepsy in pregnancy

Management of epilepsy in pregnancy:

Heart disease

    • Complicates 1% of pregnancies

     

    • Includes congenital heart disease, rheumatic heart disease (still prevalent in ethnic minorities) and specific conditions that affect the heart e.g. Marfan’s syndrome

     

    • Pregnancy puts increased stress on heart as blood volume and cardiac output (due to increase in heart rate and stroke volume) both increase by 40%

     

    • Risks to mother: death (usually due to pulmonary obstruction), cardiac arrhythmias, cardiomyopathy

     

    • Risks to baby: growth restriction, preterm delivery, 5% increase in risk of CHD if a parent affected

     

    • Patients with severe decompensated cardiac disease are advised against pregnancy

     

     

    Management of heart disease in pregnancy

    Management of heart disease in pregnancy:

     

    N.B: Warfarin is associated with an increased risk of congenital malformations if taken in the first trimester and placental and fetal haemorrhage if taken in third trimester.

     

    Hypertension

      • Complicates 5-7% of all pregnancies

       

       

      • Fetal risks: related to severity of maternal hypertension and gestational age at delivery, growth restriction (due to placental insufficiency)

       

      • Management:

       

      - Avoid ACE-inhibitors (risk of adversely affecting fetal BP, damage to fetal renal function, skull defects and oligohydramnios)

       

      - First line anti-hypertensive in pregnancy is methyldopa

       

      - Admit for bedrest if hypertension is severe

       

      - Careful monitoring for fetal growth restriction throughout pregnancy

       

      - CTG monitoring throughout labour

       

      - Ideal: vaginal delivery but low threshold for caesarean section

       

      - Magnesium sulphate administered if risk of eclampsia

       

      - BP will usually drop to pre-pregnancy levels following delivery but need to monitor mother for 48hr for eclampsia

       

       

      Thyroid disease

       

      1. Hyperthyroidism:

      - Affects 0.2% of pregnancies

      - Maternal risks: cardiac arrhymias, diarrhoea, vomiting, abdominal pains, psychosis

      - Fetal risks: growth restriction, stillbirth, tachycardia, premature delivery, if mother has autoimmune hyperthyroid autoantibodies can cross the placenta causing fetal thyrotoxicosis and goitre

      - Management: treat with lowest possible dose of propylthiouracil (does cross the placenta, occasionally causing fetal hypothyroidism but less than carbimazole)

      - Radioactive iodine is contraindicated in pregnancy (it destroys the fetal thyroid gland)

       

       

      2. Hypothyroidism:

         

      - Affects 1% of pregnant women

      - Thyroid function tests need to be performed 6-weekly throughout pregnancy to ensure optimum treatment with thyroxine

      - Maternal risks: post-natal depression, higher risk of pre-eclampsia

      - Fetal risk: cretinism (severe physical and mental developmental delay due to congenital hypothyroidism)

       

      Asthma

       

      - Common in pregnancy and usually does not cause any problems

      - Asthma medications are safe to use during pregnancy

      - If asthma is poorly controlled there is a higher risk of fetal growth restriction

      - Avoid general anaesthesia in labour, ergometrine and NSAIDs, as they are all associated with bronchospasm#

       

      Final note

       

      Ideally women should be on as few (and preferably no) medications throughout pregnancy. This is because the effects of most medications on pregnancy are unknown as clinical trials are restricted in pregnant women. However the following medications should be avoided completely in pregnancy if at all possible: 

       

      - Lithium (bipolar disease)

      - Isotretinoin (acne)

      - Some antibiotics (tetracycline, doxycycline and streptomycin)

      - Methotrexate (chemotherapy agent/antimetabolite)

       

      Nevertheless it is important to weigh up the risk: benefit ratio. In some cases the risk of stopping the medication is higher than the potential risk of taking it throughout pregnancy. As always it is important to consider each case individually.

       

      References

       

      Impey L, Child T. Obstetrics and Gynaecology. 3rd edition. Wiley-Blackwell; 2008. pp. 165-185

      Campbell S, Lees C. Obstetrics by Ten Teachers. 17th edition. New York: Oxford University Press; 2000. pp. 141-161

      British National Formulary. 58th Edition, London; BMJ Group and RPS Publishing 2009, September 2009. pp. 831-851.

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