Diabetes Mellitus in Pregnancy

Please note that NICE guidelines are due to be published in 2008 entitled "Diabetes in pregnancy: management of diabetes and its complications from pre-conception to the postnatal period".

Diabetes is the most common pre-existing medical disorder complicating pregnancy in the UK. Type 1, 2 and gestational diabetes affect 2-5% of pregnancies in England and Wales.¹ The numbers of people with Type 1 diabetes and the prevalence of Type 2 diabetes amongst women of child bearing age is increasing. Pregnancies of women with diabetes are regarded as high-risk for both the woman and the baby.² Only 10% of diabetes in pregnancy is pre-gestational and is mostly in women with Type 1 diabetes. 90% is gestational diabetes.³ Please refer to the separate article on Gestational Diabetes.

This enquiry, published in February 2007, looked specifically at diabetes in pregnancy and whether we are providing the best care. It examined the outcomes of 3808 pregnancies between March 2002 and February 2003. It found that the St. Vincent declaration in 1989 stating that 'in five years, the outcome of diabetic pregnancy should approximate that of a non-diabetic pregnancy'⁵, has not yet been achieved. It found that there was suboptimal pre-conception and pregnancy care including pre-conception counselling, glycaemic control before and during pregnancy, appropriate screening and management of diabetes complications and fetal surveillance during pregnancy. Various clinical skills and training issues for medical staff were found to be a cause of this as well as social and lifestyle issues for the woman. Maternal social deprivation was found to be associated with poor pregnancy outcome. Half of the women in the enquiry also had suboptimal postnatal diabetes care.

The findings support the argument that preparation for pregnancy, glycaemic control, and the standard of preconception and pregnancy care need to be improved if better pregnancy outcomes are to be achieved for women with diabetes.

Diabetes causes a rise in blood glucose above normal physiological levels. Pregnancy causes a physiological reduction in insulin action. This means that women with diabetes have an increased requirement for insulin during pregnancy. There are various complications that the pregnancy may face. Preconception care and good glucose control before and during pregnancy can reduce these risks.^2,6,7,8

Increased risk of complications of diabetes

• Ketoacidosis.
• Hypoglycaemia: Almost half of the women in the Confidential Enquiry had recurrent hypoglycaemia during pregnancy, although there was no evidence that this was associated with a poor pregnancy outcome for the baby.⁴
• Progression of microvascular complications including retinopathy and nephropathy: Poor glycaemic control in the first trimester and pregnancy-induced or chronic hypertension are independently associated with the progression of retinopathy.⁹ Worsening nephropathy can affect maternal blood pressure and nephropathy with superimposed pre-eclampsia is the most common cause of pre-term delivery in women with diabetes.²

Increased risk of obstetric complications

• Pregnancy-induced hypertension: Women with Type 2 diabetes are at increased risk of hypertension during pregnancy.¹⁰
• Thromboembolism.
• Premature labour: Babies are 5 times more likely to deliver before 37 weeks.
• Spontaneous abortion.⁷
• Obstructed labour: In the Confidential Enquiry twice as many singleton babies were macrosomic (had a birth weight of ≥ 4000g) compared to the general maternity population. 8% of babies had shoulder dystocia (compared to 3%).⁴
• Polyhydramnios.
• Maternal infection.
• Caesarean section: The Confidential Enquiry found a 67% caesarean section rate compared to 22% in the general maternity population.⁴

Increased risk of fetal and neonatal complications

• Late intrauterine death/stillbirth: The Confidential Enquiry showed a fivefold increased risk of stillbirth.⁴
• Fetal distress during labour.
• Congenital malformation: Neurological and cardiac abnormalities are particularly common. A twofold increased risk of congenital anomaly was found in the Confidential Enquiry.⁴
• Hypoglycaemia.
• Respiratory distress syndrome.
• Jaundice.
• Babies of women with diabetes were 10 times more likely to have Erb's palsy in the Confidential Enquiry (risk increased in a macrosomic baby who may go through a difficult delivery).⁴
• Increased perinatal mortality: The enquiry showed a threefold increased risk of perinatal mortality (i.e. death within the first month of life).⁴

This should include:

• Diet and lifestyle advice.
• Provision of appropriate contraception to ensure that an unplanned pregnancy is avoided.
• Smoking cessation support.
• Advice on reducing or cutting out alcohol.
• Assessment and management of diabetes complications.
• Advise about the benefits of good blood glucose control prior to conception. HbA1c should be checked and a midwife or diabetes specialist nurse should establish that the woman is able to use her blood glucose meter correctly and that it has been calibrated.
• Setting of glycaemic control targets, regular self-monitoring and review to allow optimal glycaemic control before conception. Monitor blood glucose at least 4 times per day. HbA1c should be < 7%. Home blood glucose tests should not be higher than 5.5 mmol/l before meals and 7.7 mmol/l 2 hours after meals.
• Discussion of diabetes pregnancy risks and their management including risk of congenital malformations, risk of obstetric complications and effect of pregnancy on diabetic complications.
• Documentation of the care and counselling given.
• Referral of the woman to a preconception diabetes clinic if available, or to their local diabetes care team. Contraception should be continued until the woman is seen.
• Review of current medication:
  • Stop ACE inhibitors and switch to methyldopa if antihypertensives are still needed. Labetolol and nifedipine can also be used². Diuretics and beta-blockers are not advised in pregnancy and should be discontinued/changed.
  • Discontinue statins.
  • Women with Type 2 diabetes on oral hypoglycaemics may need to be changed to insulin by their diabetes care team. Recent studies suggest that oral hypoglycaemics can be used in pregnancy without increased risk of congenital malformations. It is thought that it is the level of glycaemia at conception that is important in the development of anomalies and not the use of certain oral hypoglycaemics. Women should make an informed decision about their care.
• Prescription of 5mg folic acid until the woman is 12 weeks pregnant. Women with diabetes are at increased risk of having babies with neural tube defects. This dose is only available on prescription.
• Explanation of the benefits of breastfeeding (improved blood glucose control, easier weight loss).

Care should be multidisciplinary involving an obstetrician, a diabetes physician, a diabetes specialist nurse/diabetes midwife, a dietician and the GP.
All of the steps above should be followed plus the woman should be referred urgently to local diabetes antenatal clinic for:

• A dating ultrasound scan before 13 weeks.
• Review and monitoring of blood glucose control: It is accepted that most insulins can be used safely in pregnancy but there is limited safety evidence with some of the newer insulin analogues.
• Advice about hypoglycaemia: The risk of hypoglycaemia is increased in early pregnancy. Close family members should be advised how to recognise, manage and treat this, including the use of glucagon injections. Prolonged hypoglycaemia may result in intrauterine growth retardation which is associated with higher rates of neonatal mortality and long-term cognitive deficits in the baby.¹¹
• Advice about ketoacidosis: Ketoacidosis is particularly dangerous in pregnancy so women should also be prescribed and taught how to use ketone testing strips.
• Retinal assessment: An experienced physician, ophthalmologist or optometrist should perform a detailed retinal examination on all patients during the first and third trimester. Treatment should be started as necessary. Women with existing retinopathy are at increased risk of this progressing during pregnancy and should have more frequent retinal examination.
• Assessment of renal function including assessment of albuminuria.
• Dietary advice.
• Additional fetal ultrasound scanning and monitoring as needed: A detailed anomaly scan should be performed between 18-22 weeks with detailed examination of the fetal heart. Measurements of the head and abdominal circumference should be carried out monthly from 28 weeks to assess fetal growth. CTGs or biophysical profiles may be needed after 36 weeks to assess fetal wellbeing.
• If the diabetes is well controlled and there are no significant complications, the pregnancy should be able to progress to 39 weeks to achieve a vaginal delivery.
• Women should be assessed at 38 weeks to plan for delivery. It should be in a consultant-led unit with a neonatal intensive care unit and a paediatrician should be present at delivery.

• Continuous fetal heart monitoring should be carried out during labour.
• Fetal blood sampling should be performed as indicated.
• Intravenous insulin and dextrose by continuous infusion should be given to the mother, aiming to maintain maternal blood glucose between 4-6 mmol/l.
• Labour ward staff should be aware of the possibility of shoulder dystocia and have clear protocols for its management.

• The baby should be assessed by a paediatrician at birth and only be admitted to a neonatal intensive care unit if there is a specific complication.
• Hypoglycaemia (capillary blood glucose < 2.6mmol/l) is the most common complication in the first 2 days of life. Neonatal blood glucose should be monitored regularly. Hypoglycaemia is associated with adverse short and long term neurodevelopmental outcomes.¹²
• Early feeding should be encouraged to reduce the risk of neonatal hypoglycaemia and stimulate lactation.²

• Insulin requirements: When the placenta has been delivered, maternal insulin sensitivity improves. The insulin infusion rate is likely to need reducing by up to 50% and blood glucose levels should be monitored closely. Pre-pregnancy insulin doses are likely to be required except if the women is breastfeeding, when the insulin requirements will be up to 30% less.^10,13
• Breastfeeding: This should be encouraged and the baby should be offered a feed within the first hour of birth. Breastfeeding may induce hypoglycaemia in the mother and she should be encouraged to increase her intake of starchy foods.
• Contraception: This should be offered and started as soon as possible.
• Medication review: Women with Type 2 diabetes who are breast feeding usually need to continue insulin during this time. Other medication should be normalized as appropriate taking into account any restrictions with breast feeding according to specific product characteristics of the drugs.
• The mother should be seen at 6 weeks postpartum either by their GP or in a combined diabetes clinic. Pre-pregnancy advice about diabetes should be reinforced.