Diseases of the Mother in Pregnancy

1. Gestational Diabetes
   
   • Clinical Implications
   • Management
   • Risk Factors
2. Pre-Eclampsia
   
   • Symptoms
   • Risk Factors
   • Treatment
3. Quiz

• Gestational diabetes is a condition of pregnancy relating to insulin resistance (the body's cells respond poorly to insulin) that usually goes away after birth. It increases the risk of macrosomia (a larger than normal baby) and, rarely, fetal death (stillbirth). Treatment is diet and exercise changes, with metformin (a tablet that lowers blood glucose) or insulin added if blood glucose targets are not met, or insulin straight away if the fasting plasma glucose (blood glucose after fasting) at diagnosis is 7.0 millimoles per litre (mmol/L) or more. Risk factors include a BMI of 30 kg/m² or more, a first-degree relative (such as a parent, brother or sister) with diabetes, a previous baby weighing 4.5 kg or more, previous gestational diabetes, and an ethnicity with a high prevalence of diabetes.
• Pre-eclampsia involves new hypertension after 20 weeks of pregnancy, together with at least one of: new proteinuria (protein in the urine), maternal organ dysfunction or uteroplacental dysfunction (the placenta not working properly). It can first present after birth. Risk factors include age 40 years or over, a BMI of 35 kg/m² or more, high blood pressure or pre-eclampsia in a previous pregnancy, a family history of pre-eclampsia, and some existing conditions such as chronic hypertension, kidney disease, autoimmune disease or diabetes. Management includes antihypertensives (drugs that lower blood pressure) and appropriately timed birth, followed by continued maternal monitoring.

Gestational Diabetes

Gestational diabetes is a condition characterised by episodes of hyperglycaemia (high blood glucose) during pregnancy due to insulin resistance (the body's cells respond poorly to insulin). Gestational diabetes usually goes away after birth. Pregnancy normally makes the mother's cells less responsive to insulin, and the pancreas normally makes extra insulin to compensate. Gestational diabetes develops when the pancreas cannot make enough extra insulin. Women who already have insulin resistance, for example with obesity, are more likely to develop gestational diabetes. NICE advises assessing the risk at the booking appointment (the first appointment with a midwife or doctor in pregnancy). The assessment uses the risk factors listed below, not blood tests such as fasting glucose or HbA1c (a measure of average blood glucose over the past 2 to 3 months). Women with a risk factor are offered testing.

Clinical implications of gestational diabetes can be serious and include:

• Miscarriage and congenital malformation (a structural problem present from birth) are recognised risks of diabetes that was already present before pregnancy, particularly when blood glucose is high in early pregnancy. In gestational diabetes the malformation risk is only slightly raised, probably because some women have undiagnosed type 2 diabetes. NICE therefore advises measuring HbA1c when gestational diabetes is diagnosed, to find women who may already have type 2 diabetes. Good glycaemic control (keeping blood glucose within target) reduces these risks.
• Increased incidence of macrosomia (a larger than normal baby). Macrosomia increases risk of shoulder dystocia which is an obstetric emergency (an emergency in childbirth; obstetrics is the care of women in pregnancy and birth). Shoulder dystocia is when the shoulders of the baby get stuck in the birth canal. This can lead to significant fetal morbidity and mortality. There can also be a risk to the mother of postpartum haemorrhage (heavy bleeding after birth) and perineal tears (tears of the perineum, the area between the vagina and anus). Brachial plexus injury (damage to the nerves that supply the arm) to the baby is also possible.
• Increased risk of hypertensive disorders of pregnancy (conditions with high blood pressure in pregnancy). These include gestational hypertension (new high blood pressure after 20 weeks of pregnancy, without significant protein in the urine and without the other features of pre-eclampsia listed below) and pre-eclampsia.
• Increased risk of developing Type 2 Diabetes Mellitus (T2DM) after delivery.

Diagnosis of gestational diabetes is by a 75 g oral glucose tolerance test (a fasting blood test, then a 75 g glucose drink, then a second blood test 2 hours later). Gestational diabetes is diagnosed if the fasting plasma glucose is 5.6 millimoles per litre (mmol/L) or more, or the 2 hour plasma glucose is 7.8 mmol/L or more. Women with a risk factor (listed below) are offered this test at 24 to 28 weeks of pregnancy. Women who have had gestational diabetes before are offered either early self-monitoring of blood glucose or the test as soon as possible after booking. They are then offered a second test at 24 to 28 weeks if the first is normal.

Management

• Dietary modification, similar to initial management of T2DM, focusing on balanced meals and controlled carbohydrate intake (for example regular meals, low glycaemic index starchy foods that release sugar slowly, and fewer sugary foods and drinks).
• Regular exercise, such as walking for 30 minutes after a meal.
• Referral to a dietitian (a specialist in food and nutrition)
• Self-monitoring of blood glucose with finger-prick tests, usually fasting and 1 hour after each meal. NICE advises target levels below 5.3 mmol/L fasting and below 7.8 mmol/L 1 hour after meals.
• Medicines: if the fasting plasma glucose at diagnosis is below 7 mmol/L, diet and exercise changes are tried first. Metformin (a tablet that lowers blood glucose) is offered if targets are not met within 1 to 2 weeks, and insulin is added if targets are still not met. Insulin is offered instead if metformin cannot be used or is not acceptable to the woman. If the fasting plasma glucose at diagnosis is 7.0 mmol/L or more, insulin (with or without metformin) is offered straight away, with diet and exercise changes. Immediate insulin, with or without metformin, can also be considered if the fasting plasma glucose is 6.0 to 6.9 mmol/L and there are complications such as macrosomia or hydramnios (too much amniotic fluid, the fluid around the baby).
• Ultrasound scans of fetal growth and amniotic fluid volume (the fluid around the baby) every 4 weeks from 28 to 36 weeks, to look for macrosomia.
• Timing of birth: women with gestational diabetes are advised to give birth no later than 40 weeks plus 6 days. Induction of labour (starting labour artificially) or caesarean section (an operation to deliver the baby through the abdomen) is offered if they have not given birth by then. Earlier birth is considered if there are maternal or fetal complications.
• After birth: glucose-lowering medicines are stopped immediately. A fasting plasma glucose test is offered 6 to 13 weeks after the birth to exclude diabetes. If it is normal, an HbA1c test is offered every year, because of the raised risk of type 2 diabetes.

Risk Factors

• Maternal BMI of 30 kg/m² or more
• A first-degree relative (such as a parent, brother or sister) with diabetes
• Previous baby weighing 4.5 kg or more (macrosomia)
• Previous gestational diabetes
• An ethnicity with a high prevalence of diabetes: South Asian, Black, African-Caribbean or Middle Eastern origin

Preview the Diseases of the Mother in Pregnancy quiz