Babies born to women who have diabetes during pregnancy, either already existing or gestational, are at increased risk of low blood sugars after birth. This is because the babies have been exposed to higher than usual blood sugar (glucose) levels during the pregnancy and so have been producing relatively high levels of insulin. Some of these babies require additional breast milk, formula feeds or transfer to a special care nursery for intravenous fluids to correct the low blood sugar levels.

Some maternity care providers and women propose that expressing and storing colostrum, the initial nutrient-rich breast milk, during pregnancy, can be given to the baby if they develop low blood sugars after birth. This may help avoid the need for formula feeds if breastfeeding, intravenous fluids and separation from the mother if the baby has to go to the special care nursery. Although this process seems logical and is sometimes recommended, two small observational studies have shown that mothers who expressed breast milk during pregnancy were more likely to have their babies early and more of the babies were cared for in the special care nursery compared with those whose mothers did not express.

This systematic review sought to identify randomised controlled trials comparing outcomes for women with diabetes who were advised to express with women not advised to express and store breast milk during pregnancy. The search did not find any completed trials, although one trial is currently underway.

There is no high level evidence about the potential benefits and harms of the expression and storage of breast milk during pregnancy by women with diabetes.