Blood glucose control throughout pregnancy
Blood sugar control is important throughout pregnancy but for different reasons. In the early stages of pregnancy it is important for the healthy development of the foetus and in the later stages, it is important to avoid hyperglycaemia because of the impact on the baby’s metabolism.
Excess glucose in the mother’s circulation easily passes through the placenta to the baby and it is as if it is eating sweets all the time. This stimulates insulin production in the baby, insulin is a potent growth hormone and so fat is deposited which can result in a large baby which can lead to complications at delivery because the baby will not easily fit through the birth canal. After delivery the baby still produces large amounts of insulin which can result in the new born baby being hypoglycaemic. The hypoglycaemia can be dealt with by the paediatrician.
The first trimester – the first 3 months
Low blood sugars are more common during the first 3 months of pregnancy because the baby begins to feed off the mother’s glucose stores. In addition to this, the hormones are working hard to create the placenta and this can make it hard to control blood sugars. So it is important to blood test frequently and be prepared for unexpected hypos. Sometimes during this period the symptoms of hypos may change and you may not always recognise them, so it is advisable to warn friends and work colleagues about the signs of hypos. If you don’t already have glucagon for emergencies, then it may be a good idea to discuss this with your doctor. Glucagon is an emergency drug/hormone that is injected if you have a severe hypo and are unconscious and so cannot eat or drink. It works by making the liver release its own stores of glucose.
Morning sickness is common in 70% of pregnant women. It is worse on an empty stomach and some women find that eating a cracker or something similar may help. It may also help to make sure that you have a bedtime snack with protein and carbohydrate. Sometimes eating smaller and more frequent meals helps. If morning sickness is a real problem, you should discuss this with your dietitian. If it is so severe that you are vomiting up to 10 times a day, then you should call your doctor because there is a risk of ketoacidosis [very high blood sugars that are out of control].
The doses of insulin you need may change frequently because of the body’s hormone activity during this time. It may also be necessary to change your insulin regime – your meal times and injection times.
The second and third trimesters [4 to 9 months]
During this time insulin requirements usually increase and could be as high as two or three times your normal daily amount. This is because the placenta produces a hormone that makes it more difficult for the insulin to work. So frequent testing and dose adjustments when necessary, are essential. Once the baby is born, insulin requirements quickly drop back to normal.
During this time the doctors will continue to monitor your blood glucose levels, blood pressure and kidney function. Some women with and without diabetes develop high blood pressure and oedema [fluid retention causing swelling] during the latter part of their pregnancy. If this is left untreated it can lead to pre-eclampsia which puts both mother and baby at risk.
Many women with diabetes go into labour on their own and delivery is normal but this depends largely on the baby’s size and position. Women with diabetes tend to have bigger babies and so if the baby is large it may have problems moving safely through the birth canal. This is one of the reasons the healthcare team monitor the health and size of the baby very closely. If the baby is large then labour may be induced.
The decision to induce labour is usually taken after 36 weeks and this will depend on the baby’s size, the maturity of its lungs, the health of the placenta and the mother’s health.
If the baby is too large or the health of mother and baby is at risk then a Caesarian section will be carried out. This is much more common in women with diabetes than in women without diabetes.
There is an interesting diabetes and pregnancy case study on the NHS Choices website: