Diabetes and pregnancy

What is diabetes?

Diabetes mellitus (just called diabetes from now on) occurs when the level of sugar (glucose) in the blood becomes higher than normal. There are two main types of diabetes. These are type 1 diabetes (this usually starts in childhood or adolescence and requires insulin treatment from the start) and type 2 diabetes (this usually starts in adulthood and often can be managed with diet or tablets).

For further information about diabetes, see the separate leaflets called Type 1 diabetes and Type 2 diabetes.

Sometimes pregnancy causes the blood sugar to rise in women who do not have diabetes. This is called gestational diabetes (see below).

How does pregnancy affect diabetes?

During pregnancy, the body needs more insulin to control the levels of sugar (glucose). Therefore, women with diabetes usually need higher doses of medication or more medication to control their blood sugar during their pregnancy.

If diabetes is not well controlled during the pregnancy this may cause harm for both the mother and baby. Therefore more frequent check-ups with the obstetrician are normally advised and usually this will be in a joint clinic with an obstetrician and a diabetes specialist working together. This will help to reduce the risks and help to ensure a healthy mother and baby at the end of the pregnancy.

What is gestational diabetes?

Gestational diabetes mellitus (GDM) is the name for diabetes which starts for the first time during pregnancy and which usually resolves soon after giving birth. Research shows that gestational diabetes occurs in between 1 in 20 and 1 in 50 of all pregnancies. Gestational diabetes usually starts in the second half of pregnancy.

The risks of having gestational diabetes - both for mother and baby - are similar to those for women who have known diabetes. This includes a higher chance of needing a caesarean section (see below). Most women with gestational diabetes recover after the pregnancy but there is a high risk of it recurring in a future pregnancy. Women who have had gestational diabetes are also at increased risk of developing diabetes in the future - it is recommended that all women who have had gestational diabetes have a blood test for diabetes once a year.

Risk factors for gestational diabetes

Gestational diabetes is more common in women who are over 35 when pregnant, women who are obese (BMI above 30) and women who smoke. There is also an increased risk for:

• Women who have had GDM in previous pregnancies.

• Women who have had a short time interval between pregnancies.

• Women who have had a previous unexplained stillbirth.

• Women who have had a previous baby with very high birth weight (4.5 kg or more).

• Women with an immediate family member (brother, sister or parent) with diabetes.

• Women from some ethnic groups (South Asian, black Caribbean and Middle Eastern).

Diagnosis of gestational diabetes

The glucose tolerance test (GTT) can be used to test for GDM. The current National Institute for Health and Care Excellence (NICE) guidance recommends that:

• Woman who have had GDM in a previous pregnancy should be offered early self-monitoring of blood sugar (glucose) or a two-hour 75 g GTT as soon as possible after the first antenatal appointment. This is followed by a repeat GTT at 24-28 weeks of pregnancy if the first test is normal.

• Women with other risk factors (see above) should have a GTT at 24-28 weeks.

Treatment of gestational diabetes

Gestational diabetes can cause serious consequences for women and their babies but these can be greatly reduced by treatment.

Treatment includes following advice about diet and physical activity. Medicines to lower the blood sugar levels may be required. The medicines may be tablets (for example, metformin) but insulin injections may also be needed. These medications are safe in pregnancy.

After your pregnancy

Insulin and other medicines to control blood sugar in gestational diabetes are usually stopped immediately after delivery.

Most women with gestational diabetes recover after the pregnancy but there is an increased (2 in 3) risk of it returning in a future pregnancy. Women who have had gestational diabetes are at increased risk of developing diabetes in the future. It is recommended that women with a history of gestational diabetes:

• Avoid being overweight.

• Take regular exercise.

• Don't smoke.

• Try to avoid having pregnancies with only a short time interval (a few months) between each pregnancy.

• Attend the six-week postpartum check and have a blood sugar test taken.

• Have their blood sugar level checked each year.

What is the advice for women who have diabetes before pregnancy?

The risk of problems for women and their babies can be greatly reduced by the following advice:

• Avoid unplanned pregnancies. It is very important to plan any pregnancy and so contraception is very important.

• Good control of blood sugar (glucose) levels before and during pregnancy reduces the risks of stillbirth, miscarriage, congenital malformation and neonatal death.

• It is essential to follow dietary advice, weight control and exercise advice given to all people with diabetes.

• It is very important to attend regular checks for any complications of diabetes, including regular eye assessments and other assessments and appointments with your practice nurse, GP or specialist. Complications of diabetes can worsen during pregnancy.

• Women with diabetes who are planning to become pregnant should take 5 mg of folic acid daily until 12 weeks of pregnancy to reduce the risk of birth defects in the baby.

• Ketone testing strips should be used to test for ketones if unwell. Ketones are substances the body makes if there is a lack of insulin in the blood.

• It is even more important to stop smoking before pregnancy.

• Reduce or cut down on the amount of alcohol you drink.

• Think very positively about breastfeeding because it improves blood sugar control and makes it easier to lose weight after giving birth.

Treatment of diabetes in pregnancy

As stated above, most women require more medications or higher doses of their medication during pregnancy.

The National Institute for Health and Care Excellence (NICE) recommends that women with type 1 diabetes should be offered continuous glucose monitoring (CGM) throughout their pregnancy. Women with type 1 diabetes who cannot use CGM should be offered intermittently scanned CGM (commonly referred to as flash glucose monitoring).

Women who do not have type 1 diabetes but have type 2 diabetes or gestational diabetes and need insulin should also be offered continuous glucose monitoring if their blood glucose is unstable or they have severe problematic 'hypos'.

Women with diabetes will usually be advised to take aspirin during their pregnancy from 12 weeks to 36 weeks. This reduces the risks of having pre-eclampsia or a low-birthweight baby.

What are the risks of having diabetes during pregnancy?

There are various complications that may occur. Pre-conception care and good blood sugar (glucose) control before and during pregnancy can reduce these risks.

Problems during pregnancy

• Premature birth: babies are more likely to be born early (before 37 weeks).

• There is an increased risk of miscarriage or of the baby dying late in the pregnancy (stillbirth).

• Babies tend to be a higher birth weight and this may make giving birth more difficult. There is an increased risk of the baby becoming distressed during labour (fetal distress).

• There may be too much fluid around the baby (polyhydramnios).

• There is an increased risk of infections during pregnancy and these infections may be more serious.

• There is an increased chance of needing to give birth by caesarean section.

Problems for the baby after pregnancy

• Congenital abnormalities are more common. This includes heart abnormalities, neural tube defects and problems with the bones, amongst others.

• Low blood sugar (hypoglycaemia) is common and may be severe.

• Respiratory distress syndrome is more likely.

• Jaundice is more common.

• Birth injury is more likely.

• There is an increased risk of the baby dying soon after birth.

Problems for the mother

• There is an increased risk of problems during the pregnancy, including high blood pressure and blood clots.

• There is an increased risk of the blood sugar being very high (ketoacidosis) or too low.

• There is also risk that long-term diabetes complications may become worse, including eye problems and kidney problems.

What is the treatment?

It is essential to have regular checks of the diabetes control and checks of your baby, along with the checks that all women need during pregnancy. A specialist will be involved to help look after the diabetes and the unborn baby.

It is recommended that women who have diabetes give birth in hospital. There is a higher risk that the baby may be distressed and it is essential that specialist care is immediately available.

What is the outlook?

Although diabetes in pregnancy is associated with higher risks, these risks are lessened by frequent checks and good treatment.