Gestational diabetes - Diabetes in pregnancy

Diabetes can develop during pregnancy in a woman who hasn't previously had the condition. This is called gestational diabetes, which affects two to three per cent of pregnant women. If it is not properly controlled, it can lead to problems for the mother or her baby.

What is gestational diabetes?

Gestational diabetes develops in women during pregnancy because the mother's body is not able to produce enough insulin. Insulin is a hormone that enables the body to break down sugar (glucose) to be used as energy. Without sufficient insulin the amount of sugar in the blood rises.

High blood sugar levels in the mother's body are passed through the placenta to the developing baby. This can cause health problems.

Gestational diabetes usually begins in the second half of pregnancy, and goes away after the baby is born. This makes it different to the more common forms of diabetes which, once they occur, are permanent.

What causes gestational diabetes?

The cause of gestational diabetes is unknown. It is thought that the hormones produced during pregnancy may block the action of insulin. Gestational diabetes can happen if the mother's body can't produce enough extra insulin to counteract this blocking effect.

Risk factors

Although there is no clear reason why some women get gestational diabetes, women are more at risk if they:

• have a family history of type II (adult-onset) diabetes
• are over the age of 35
• are obese
• have previously given birth to a large baby
• have previously given birth to a baby born with an abnormality
• have previously had a stillbirth late in pregnancy

Symptoms

In most women, gestational diabetes causes no symptoms. Some women do get symptoms of high blood sugar, such as increased thirst, increased need to pass water and increased hunger, although these are also common later on in pregnancy anyway.

The effects of gestational diabetes

Effects on the fetus during pregnancy

• Having high blood sugar can cause the baby to grow larger, which can make delivery difficult and potentially cause injuries to both mother and baby during birth. In some cases a caesarean section is necessary.

Effects on the baby after birth

• The baby may have low blood sugar (hypoglycaemia) after birth. This is because the baby's pancreas makes extra insulin in response to the mother's high blood sugar levels. Shortly after birth, the baby may continue to make extra insulin even though high levels of blood sugar are no longer present. After a pregnancy affected by gestational diabetes, the newborn baby's blood sugar level is checked regularly. Sometimes babies are given an early feed of a sugar (glucose) solution through a drip (fed directly into a vein) to correct low blood sugar.
• It is more likely that the newborn baby will develop jaundice (yellowing of the skin and whites of the eyes). This is not serious and usually fades over a few weeks, without the need for medical treatment.
• There is an increased risk that the baby will be born with congenital problems, such as a heart defect. Sometimes, infants can be born with respiratory distress syndrome, in which the baby has problems breathing because his or her lungs have not matured as normal. This usually clears up with time.
• There is also a slightly higher chance of stillbirth or death as a newborn, but if detected and the glucose levels well managed, death is rare.
• There may be an increased risk of the baby developing type II diabetes or being overweight later in life.

Effects on the mother

Gestational diabetes is not an immediate threat to the woman's health. Most women with gestational diabetes whose blood sugar levels stay within the safe range deliver their babies without complications. However, in some women it can result in high blood pressure.

Women who get gestational diabetes are more likely to develop gestational diabetes in future pregnancies, and are at a higher risk of developing type II diabetes later in life.

Diagnosing gestational diabetes

Urine is routinely tested for sugar throughout pregnancy, and high blood sugar, if present, is usually detected between 24 and 28 weeks of pregnancy.

The only way to confirm gestational diabetes is with a glucose tolerance test, which needs to be carried out after eight hours without food. The woman is given a solution of glucose to drink, and then blood samples are taken and analysed at different intervals to see how the body deals with the glucose over time.

If a doctor believes a woman is likely to develop gestational diabetes, this test may be carried out earlier than 24-28 weeks. Any woman whose medical history means she's at a greater risk of diabetes, or is concerned about any symptoms should see her GP.

Treatment

Self-help

The most important part of treatment is to control blood sugar levels. For many women, this means regular testing of blood sugar (glucose) levels, a carefully planned diet and regular exercise.

Home glucose testing kits are available from chemists. These usually involve taking a tiny blood sample with a pinprick device. The blood is put onto a strip and inserted into a glucose measuring device, which gives the blood glucose level.

Doctors usually advise blood glucose testing once a week, although for some women this may need to be more often. Glucose needs to be measured in the morning before breakfast and again two hours after breakfast. Some women may also need to test levels in the mid-afternoon.

A doctor or dietician can give advice about what and how much to eat. A meal plan will probably consist of a variety of foods including plenty of starchy fillers such as bread, pasta, rice and potatoes, and at least five portions of fruit and vegetables each day.

It's important to limit consumption of sugary foods like cakes, biscuits and soft drinks. A diet that is low in fat is also desirable. This can be acheived by avoiding full-fat dairy products such as butter and cream, and limiting fatty meat, pies, sausages and burgers. Grilling, steaming or microwaving food rather than frying or roasting means less fat is added during cooking.

Gentle, regular exercise such as walking can help reduce blood sugar levels and promote a sense of well-being. A doctor or midwife can advise about suitable exercise during pregnancy.

Medicines

Despite making the above lifestyle changes, a few women's blood sugar levels remain too high, and they may need daily injections of insulin. The extra insulin will not cross the placenta and will not affect the baby. Any woman who needs to take insulin will be taught how to take it by her doctor or nurse.

It is possible to have too much insulin and this can cause low blood sugar (hypoglycaemia). Common symptoms of this are weakness, shaking, hunger and sweating. For people taking insulin, it is a good idea to keep a snack handy at all times in case low blood sugar develops.

After the birth

In almost every case, gestational diabetes disappears on its own after delivery. To be sure, doctors may check the mother's blood sugar levels a few times after the birth.

Prevention

To help reduce the risk of getting gestational diabetes, women should make healthy lifestyle choices, such as eating a balanced diet, taking regular exercise and maintaining the correct weight for their height