In Canada, diabetes in pregnancy affects almost four per cent of pregnancies. The rate is as high as 18 per cent in First Nations populations. Gestational diabetes often resolves once the baby is born, and is thought to be a hormone problem.
Women at highest risk for developing diabetes during pregnancy are those who:
Problems with gestational diabetes
Gestational diabetes can cause problems for both mother and baby. For a mother, having diabetes in pregnancy increases the risk of developing type 2 diabetes later. Complications of diabetes include heart and blood vessel disease, stroke, visual changes, kidney failure, and nerve damage. Identifying this risk in pregnancy can help a woman make lifestyle changes important to preventing type 2 diabetes in the future.
Women with gestational diabetes also run a higher risk of developing high blood pressure in pregnancy. For some, high blood pressure is a minor problem with no negative effects. For others, it can cause serious complications requiring emergency treatment and delivery of the baby.
Diabetes in the mother can mean that the baby will grow larger than usual (macrosomia). This may also be related to extra weight in the mother. Big babies are at higher risk during birth. The shoulder may get stuck during delivery, the collarbone or arm bone may fracture, nerves can be injured, or a caesarean delivery may be necessary. Delivering a big baby can also cause more injury to the mother. Injuries to both mother and baby are usually short-lived and usually do not cause long-term problems.
Diabetes in pregnancy can lead to low blood glucose levels in the baby. The unborn baby becomes used to getting a high level of glucose through the placenta. Once the baby is born and the glucose supply is gone, the baby must make its own glucose. Some babies need extra glucose from formula or intravenous (IV) fluids until their own metabolism kicks in and breastfeeding is well established.
Babies whose mothers had diabetes in pregnancy are more likely to be jaundiced (have yellowish skin). They can be low on calcium, an important mineral the heart and muscle need to work well. They may have difficulty breathing in the first hours to days of life. In the long term, these children are thought to be at higher risk for becoming obese. They may also be at risk for impaired glucose (sugar) intolerance, which often leads to type 2 diabetes.
Despite all of the possible problems, controversy about whether or not all women should be tested for diabetes in pregnancy still exists. Medical research has never proven consistently that treating diabetes in pregnancy reduces the chance of a poor outcome. It may actually increase the rate of caesarean deliveries.
Since we lack good medical evidence, screening and treatment recommendations are based largely on expert opinion. The current recommendation in Canada is that either all pregnant women at risk should be screened, or those at low risk need not be screened. Opinion in the United States is also mixed, though over 95 per cent of doctors screen. In Britain, screening is not recommended.
In Canada, women at risk can be screened between 24 to 28 weeks of pregnancy by drinking a sugary mixture and having the blood glucose level tested an hour later. If a woman's glucose levels are high, the test is positive. Her doctor or midwife may ask for a second test to confirm the diagnosis, as some women have false positive results on the first test. If her glucose levels are still high on the second test, she has diabetes in pregnancy. If her glucose levels are normal on the second test, she does not.
Some women have results that fall in the middle, called impaired glucose tolerance of pregnancy. In this case, she may be referred to a dietitian and checked to make sure she does not develop full diabetes later in pregnancy.
A woman diagnosed with diabetes in pregnancy usually monitors her own blood glucose several times a day. A drop of blood from her finger is placed on a test paper and read by a glucometer. Urine may also be tested to see if glucose is spilling into the urine through the kidneys or to look for ketones. Ketones in urine are a sign that glucose control is not very good. Some women can control blood glucose using simple dietary changes and regular exercise. Others may require insulin injections in addition to changes in diet and exercise.
At present, some women may take oral diabetes medication before starting insulin injections. Recent studies suggest oral medications are likely safe for some women. More results are expected in the next few years. Ideally, women with gestational diabetes should see a dietitian and an endocrinologist (a doctor who specializes in diabetes) regularly. If blood glucose can be kept as normal as possible, the possibility of problems during and shortly after birth may be reduced.
During labour, women who took insulin to control their diabetes will have their blood glucose monitored closely. Insulin may be needed during labour. The blood glucose of the baby must be tested a few times in the first day of life to be sure the level does not drop too low. Frequent breastfeeding is encouraged for these babies.
Women who experience diabetes in pregnancy should have a blood glucose test several weeks after delivery. Glucose levels will be checked to make certain that they have returned to normal. The family doctor can discuss ways to reduce the risk of developing diabetes in the next pregnancy and later in life. Long-term lifestyle improvements are extremely important. Regular exercise, a healthy diet, maintaining a healthy weight, and not smoking can all make a difference. Changes can be achieved and maintained more easily by a woman who has the support of her family and doctors.