What is antenatal expressing?

Antenatal expressing is the practice of hand expressing the early breastmilk (colostrum) before the birth of your baby. The colostrum is usually collected and stored in syringes with a unique cap, labelled with date and time of collection and frozen. The stored colostrum is then defrosted during your labour. It is then ready to feed to the baby if there is a delay.

Why do it?

Having a store of colostrum can be valuable, especially in the case of women with gestational diabetes (GDM). Babies born to women with GDM require frequent feeds to ensure baby’s blood glucose doesn’t drop below normal levels. Feeding this expressed milk in the first few hours after birth may support the baby to stabilise its sugars. It may also be useful under other circumstances. For example, women who want to breastfeed exclusively may choose to express breastmilk. That way if the baby doesn’t latch well they still get colostrum.

What’s the evidence?

Historically, recommendations around antenatal expressing were logic based. However, these practices evidence-based. In 2011-12 two studies looked at the birth outcomes for women expressing milk before their babies were born (1,2). These found that babies were more likely to be admitted to the special care nursery if their mothers expressed breastmilk antenatally. They were also born a week earlier than those born of mothers who did not.

This result prompted many health services to stop recommending women express before the baby was born under all circumstances. A large study was then launched in Australia to research these connections further. Women with diabetes in pregnancy (either GDM or pre-existing) but were otherwise low risk were the study subjects. These inclusions included women whose diabetes was controlled by either diet, medication or insulin.

What are the findings?

It reported that antenatal expressing from 36 weeks did not affect on nursery admissions. That is, while it didn’t appear to increase the risk of a baby’s admission to the nursery, it also didn’t reduce the nursery admission rate. In other words, while it didn’t do any harm, it didn’t act to protect babies of GDM mums from needing nursery care.

The study also found that there was statistically no difference between the preterm birth rate in expressing and non-expressing mums and that how many weeks and day baby was at birth was about the same. In other words, no effect, harmful or beneficial.

It did find that babies of mothers who expressed antenatally were more likely to be fed breastmilk only during their hospital stay and in the early weeks of life. This effect did not last beyond three months of age. These findings are of great value when we look at breastmilk and its role in long term infant health. In particular, it may act to establish the infants’ microbiome and protect the baby against future diabetes.

Is antenatal expressing for me?

The finding of this research only applies to the women included in these groups – with diabetes in pregnancy but otherwise low risk. The expressing commenced at 36 weeks. Under these circumstances, the research supports antenatal expressing as there is no evidence of harm, and it supports a family’s wish to breastfeed exclusively. There is no substantial evidence about this practice in women without diabetes. There is also no evidence for low-risk women or women with more complicated pregnancies.

Please speak to your doctor or midwife about the potential risks and benefits of antenatal expressing. Should you decide to express colostrum before your baby is born, please see a midwife or lactation consultant to learn correct expressing and storage techniques.