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Diabetes and pregnancy: what are the risks?

Joy Williams
BSC(Hons) DPSN RGN SCM
Senior Diabetes Specialist Nurse Worthing Hospital Sussex

Diabetes is the commonest pre-existing medical disease complicating pregnancy in the UK. In 2001 there were 1.3 million people in England with diabetes, and this figure is estimated to rise to three million by 2010.(2) This increase in diabetes, particularly type 2 diabetes, has meant a rise in the number of women of childbearing years presenting with diabetes.(3) The growth in diabetes has been attributed to increasing obesity, sedentary lifestyle and an ageing population.(2) Type 1 diabetes occurs when there is no insulin secretion, and is treated by insulin injection, diet and exercise. Type 2 occurs where there is insufficient insulin secretion and is often combined with insulin resistance. It is more prevalent in Asian and Afro-Caribbean ethnic groups.(4)
 
What are the complications?
The complications of diabetes are devastating and can impact on the individual and their families. Complications include blindness, renal failure, cardiovascular disease and neuropathy. For women with pre-existing diabetes, pregnancy outcomes can be worse than for the general population.
The Confidential Enquiry into Maternal and Child Health 2002-2003 was a large national study that looked at all pregnancies where the mother had pre-existing diabetes.(1) It revealed the stillbirth rate was 4.7 times higher, the perinatal mortality rate 3.8 times higher and the neonatal mortality rate 2.6 times higher than the nondiabetic population.(4) The congenital anomaly rate was twice that of the background population.(4)  It also demonstrated that the risk was with both type 1 and type 2 diabetes.(1) This dispels the myth that type 2 diabetes is a milder form of the disease. Adverse outcomes correlated with poorer HbA(1c) levels.(4)
Considering the increased morbidity and mortality associated with pregnancy in women with pre-existing diabetes, all healthcare professionals have a responsibility to inform women of the risks of hyperglycaemia and the benefits of planning pregnancy. Hyperglycaemia has been identified as a cause of miscarriage, fetal abnormality and a large or macrosomic baby. Contraception should be discussed and women advised to use a reliable method until control is optimised. Changing from an oral contraceptive to a barrier method while optimising control may be suggested.
It is important for healthcare professionals in primary care and specialist care to work collaboratively to provide a seamless service for this high-risk group. The National Service Framework for Diabetes standard 9 advocates that women with diabetes are empowered and supported in optimising their pregnancy outcomes through NHS policies.(5)
 
Preconceptual care
A full medical review by a diabetologist is advocated for women with pre-existing diabetes planning pregnancy. This will include a review of medication so that any potential teratogens can be changed. Blood pressure needs to be adequately treated to prevent renal damage. Kidney and cardiac function need to be assessed, and retinal screening and necessary treatment should be undertaken.
To reduce the risk of miscarriage and fetal abnormality, women should be advised to maintain their blood glucose levels in the normal range of 4-6mmol/l before food. The aim is to have the HbA(1c) 7% or below before conception and during organogenesis to reduce the risk of fetal abnormality. Women with type 1 diabetes should be referred to specialist care for a review of their insulin regimen to achieve optimal control. Women with type 2 diabetes will require insulin therapy to control their blood sugar levels if their diet is insufficient. 
Keeping tight glycaemic control can lead to more hypoglycaemic episodes. Women need to be advised that in pregnancy hypoglycaemia warning signs may change, or even disappear, which can be disconcerting. The woman may need to be advised to stop driving during her pregnancy if she loses hypoglycaemia awareness. Pregnant women need help and support in making changes to improve their control. If the pregnancy outcome is poor then the woman may blame herself, so the healthcare team need to offer support.
 
Risks during pregnancy
Morning sickness, or hyperemesis gravidarum, can occur in early pregnancy and may be reduced by eating small regular meals. This can be problematic for women managing insulin. Analogue insulin can be given following the meal rather than beforehand, as its onset of action is rapid. However, the woman may require hospitalisation for rehydration and sliding- scale insulin.
During pregnancy the woman with pre-existing diabetes is at an increased risk of developing pre-eclampsia, especially if she has renal impairment.(4,5) She will require close monitoring and supervision by the specialist team.
Macrosomia, where the baby is large for its gestational age, especially around the abdominal circumference, does not equate with maturity. Both mother and baby are more likely to suffer trauma delivering a large baby.
Babies that are born to mothers with diabetes are more prone to respiratory distress syndrome (RDS) than babies born to mothers who do not have diabetes.
The possibility of women with pre-existing diabetes going into preterm labour is more likely. As the baby is at risk of RDS, the mother may require steroid therapy to mature the fetal lungs. The steroids will cause the blood glucose levels to rise, so usually the mother is admitted to hospital for monitoring and sliding-scale insulin.
Delivery should be planned by the specialist team with the woman ideally before term and after 38 weeks' gestation. There is a 60% incidence of delivery by caesarean section in women with pre-existing diabetes.(1) Stillbirth is more common after term in women with pre-existing diabetes; hence the plan to deliver before term. Preterm delivery increases the risk of the infant developing RDS, so planning the optimal time is very important.

Gestational diabetes
Gestational diabetes is a carbohydrate intolerance first diagnosed in pregnancy that varies in severity. It presents later in pregnancy and does not cause fetal abnormalities because organogenesis is complete by 12 weeks gestation. Once the woman has delivered the placenta, gestational diabetes will resolve. A woman whose blood sugar levels do not return to normal has developed type 2 diabetes. Gestational diabetes is likely to return in future pregnancies.
Screening of those women with the following risk factors should be undertaken:(3)

  • Glycosurea.
  • Obesity.
  • Family history of type 2 diabetes.
  • Polycystic ovary syndrome.
  • A large-for-gestational-age infant in this or a previous pregnancy.
  • Previous stillbirth.
  • Neonatal death.

Gestational diabetes is more prevalent in ethnic groups prone to type 2 diabetes, so these groups should also be screened.(6)
Treatment is with a healthy diet - low in sugar, fat and salt and including five portions of fruit and vegetables daily. The woman should be referred to a dietitian and advised to monitor blood glucose levels. Uncontrolled gestational diabetes can result in macrosomia, causing trauma to both mother and infant during delivery.(7) Elevated levels are controlled with insulin therapy. Some women will see this as very invasive, so support and encouragement is required from the healthcare team.
Women developing gestational diabetes are at increased risk of developing type 2 diabetes. Lifestyle advice to reduce this risk after pregnancy should promote eating a healthy diet, taking regular exercise and weight management. They should also be advised to have an annual fasting blood glucose check.(6) In future pregnancies they should be referred to specialist services early and advised to monitor blood glucose levels and eat a healthy diet.

Breastfeeding is best
Breastfeeding is recommended as the optimal feeding method for babies. Early feeding is encouraged for babies of mothers with both pre-existing diabetes and gestational diabetes to reduce the risk of the baby developing hypoglycaemia. These babies often require supplementary feeds for the first couple of days to stabilise their blood glucose levels. Women with pre-existing diabetes should be advised to eat extra snacks, particularly at bedtime, as breastfeeding may cause hypoglycaemia. Insulin doses will be lower than prepregnancy.
While the outcome of pregnancy for women with pre-existing diabetes is worse than their nondiabetic counterparts, careful planning and support from the healthcare team can optimise outcomes for mother and child.

References

  1. Confidential enquiry into maternal and child health: pregnancy in women with type 1 and type 2 diabetes in 2002-2003 England, Wales, Northern Ireland. London: CEMACH; 2005.
  2. Diabetes UK. Diabetes in the UK. London: Diabetes UK; 2004.
  3. Williams G, Pickup J.  Handbook of diabetes. 2nd ed. Oxford: Blackwell Publishing; 1999.
  4. Macintosh MC, Fleming KM, Bailey JA, et al. Perinatal mortality and congenital anomalies in babies of women with type 1 or type 2 diabetes in England, Wales, Northern Ireland: population based study in BMJ. Jun 16 2006 [Epub ahead of print]. Available from: www.bmj.comdoi:10.1136/bmj.38856.692986.AE
  5. Department of Health. National Service Framework for diabetes: standards. London: HMSO; 2001.
  6. Jerreat L. Diabetes for nurses. 2nd ed. London: Whurr Publishers; 2003.
  7. Crowther C, Hiller JE, Moss JR, et al. Effect of treatment of gestational diabetes mellitus on pregnancy outcomes. N Engl J Med2005;352:2477-87.

Resources
Confidential Enquiry into Maternal and Child Health
W:www.cemach.org.uk
Department of Health
W:www.dh.gov.uk
Diabetes UK
W:www.diabetes.org.uk