Congenital malformations, also known as congenital disorders or birth defects, are conditions or defects that affect the baby from birth.

Whilst congenital disorders can result from genetic reasons, other factors such as diet, medication and also blood sugar control can play a part.

Mothers with diabetes have a greater risk of giving birth to a baby with birth defects, however, the risk can be reduced through good control of diabetes and keeping a healthy lifestyle leading up to and throughout your pregnancy

Birth defects

Whilst there are a wide range of congenital malformations that can occur, the following conditions are those that research studies have shown to be more common in babies of mothers with diabetes.

  • Spina bifida
  • Heart problems
  • Oral clefts
  • Gastrointestinal tract defects
  • Kidney defects
  • Limb deficiencies

How common are birth defects as a result of diabetes?

A UK study published in 2012 showed that congenital malformations occurred in around 7% of pregnancies of mothers that had diabetes before pregnancy (pregestational diabetes).

This represents a four times higher risk than children born to mothers without diabetes. The study mainly included mothers with type 1 diabetes (78% of the women).

Having gestational diabetes is also associated with a greater risk of birth defects, but the risk is significantly less than for mothers entering pregnancy with diabetes.

Having a BMI of under 25 going into pregnancy presents a lower risk of birth defects occurring.

Blood glucose control and risk of birth anomalies

If you have diabetes, keeping good control of blood glucose levels is one of the most important ways in which you can significantly decrease the likelihood of your baby developing congenital anomalies.

The recommended HbA1c level you should aim to achieve before and during pregnancy is 43 mmol/mol (6.1%)

Research shows that for each 11 mmol/mol (1%) rise in HbA1c above 45 mmol/mol (6.3%), the risk of birth abnormalities rises by 30%.

Whilst the blood glucose targets in pregnancy are strict, your health team should help you to achieve or get as close to the targets as possible.

Medication in pregnancy

In some cases, the medication you are currently on may not be suitable for use in pregnancy.

Medicines that are not recommended for use in pregnancy include:

  • Statins
  • Certain blood pressure medications
  • Certain medications for type 2 diabetes

If you are on any of these medications, notify your health team. Your doctor or consultant will advise whether you need to cease taking any medication or if you will need to change to a different type of drug.

Mothers to be with type 2 diabetes treated that are on medication may need to start taking insulin for the duration of the pregnancy.

Preventing congenital malformations

In addition to keeping good control of your diabetes, there are other steps you can take to further minimise the risk of birth defects occurring. These include:

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