How your diabetes can affect your baby

Diabetes and pregnancy

If you have diabetes and get pregnant, you are likely to have a healthy baby. However, it is important to be aware of some possible complications.

People with diabetes have an equal chance of giving birth to a healthy baby. This is provided that you get pregnant when your diabetes is tightly controlled and you are in good general heath.

We strongly recommend that you plan your pregnancy to get the best possible outcome. To reduce the health risks for you and your baby, you need to make sure that your diabetes is well controlled before you become pregnant. If you are already pregnant, your diabetes and pregnancy team work with you towards the best outcome for you and your baby.

The first 8 weeks are when a baby’s main organs develop. For this reason, you need to have tight control of your blood sugar (glucose) levels as soon as possible.

How high blood sugar can affect your baby

Sugar in your blood (glucose) can cross the placenta to your baby during pregnancy, but insulin does not. The placenta is an organ attached to the lining of the womb. It delivers oxygen and food to your growing baby.

Your baby stores the extra sugar and may grow more quickly than the baby of someone without diabetes. When you are about 15 weeks pregnant, your baby starts to make their own insulin (a hormone that controls the amount of sugar in the blood).

If your blood sugar is high, your baby will similarly have a high blood sugar level. This encourages your baby's pancreas to produce extra insulin, which can make your baby grow bigger and faster than needed.

If you have a large baby, this increases the chance of a difficult birth. You are more likely to have your labour induced (started artificially) or need a caesarean section.

A large baby, whether born fully developed or prematurely, may have low blood sugar (hypoglycaemia) at birth. This is because the baby continues to make extra insulin for a day or 2. Your baby could also have trouble with feeding and breathing, and other health problems.

Controlling your blood sugar levels during pregnancy and childbirth reduces the chance of all these problems. However, some babies still have problems, just like babies of some people without diabetes.

How low blood sugar can affect your baby

Low blood sugar levels do not affect your baby like they do you. 

When your blood sugar level drops low, it only affects your brain cells and not your baby's. Your baby can release sugar from their own liver if the amount of sugar that you have is too low.

Possible risks to your baby and how to avoid them

You need to be aware of some possible risks to your baby's health if you have diabetes. However, you can greatly reduce these risks by managing your diabetes well before and during pregnancy.

Risk of birth defects

Most people with diabetes have healthy babies. However, there is a slightly higher chance of your baby being born with birth defects.

  • About 2.1 out of 100 pregnancies among the general population result in birth defects.
  • For people who already have diabetes before they get pregnant, about 4.0 to 4.5 out of 100 pregnancies result in birth defects.

Damage to the heart, spine and kidneys may happen during the early stages of pregnancy when your baby's main organs are developing. This is often before you realise that you are pregnant.

To reduce your chance of miscarriage and of your baby having birth defects, keep your blood sugar within the normal healthy range. This is 4 to 7mmol/L with an HbA1c level of less than 7% (53mmol/mol). It is important to have good blood sugar control for 3 months before you get pregnant and throughout your pregnancy.

If you get diabetes during pregnancy (gestational diabetes), the chance of birth defects is not thought to be particularly higher than for the general population. Gestational diabetes usually starts in the middle or towards the end of pregnancy. This is after all of the baby's main organs have already been formed.

Risk of diabetes

If you have type 1 diabetes, the chance of your child getting this condition in future is only 5%. This means that about 5 in 100 children get type 1 diabetes in future.

The chance of your child getting diabetes is higher if their father has type 1 diabetes. In this case, 7 in 100 children (7%) get type 1 diabetes in future.

Resource number: 1702/VER4
Last reviewed: September 2022
Next review due: September 2025

A list of sources is available on request.

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