Oxytocin system of breastfeeding affected in mothers with postnatal depression

The oxytocin system – which helps release breast milk and strengthens the bond between mother and baby – may be affected during breastfeeding in mothers experiencing postnatal depression, a new study has found.

The new research investigated the link between maternal mood and the oxytocin pathway during breastfeeding in mothers with and without symptoms of postnatal depression.

The hormone oxytocin is released in both the brain and body, and plays a central role in childbirth and breastfeeding. It is also involved in social relationships, especially intimacy, and the attachment process during infancy.

In breastfeeding, oxytocin triggers the ‘let-down’ reflex that releases the mother’s milk and is stimulated in both mothers and their baby by skin-to-skin touch.

Oxytocin release also interacts with specific brain regions to reduce stress and stimulate reward associated with this, facilitating mother-infant bonding and early infant development.

Mothers experiencing postnatal depression report increased stress during breastfeeding and early weaning. Although the social context related to a mother’s depression likely contributes to this, it has not been known whether the oxytocin system may also be affected.

For the new study, 62 new mothers aged between 23 and 44 years old who had an infant between three and nine months old, were each given a nasal spray prior to breastfeeding, containing either oxytocin or a placebo.

Breast milk samples were collected during breastfeeding and analysed for oxytocin. The team found that oxytocin levels in breast milk were not affected by mothers’ mood at baseline.

However, while oxytocin was seen to increase in the breast milk of women without postnatal depression after using a nasal spray containing the hormone, this effect was reduced in mothers experiencing postnatal depression.

Lead author, Dr Kate Lindley Baron-Cohen at UCL Psychology and Language Sciences, said: “Our findings indicate that the oxytocin system is affected by postnatal depression in new mothers in the context of breastfeeding.

“Since higher levels of oxytocin in mothers are associated with positive outcomes in a child’s social development and in their mental health, these results point to a possible pathway through which infants of mothers experiencing postnatal depression may be at greater risk of later mental health vulnerabilities.”

These findings indicate a new direction for research, to further explore how oxytocin is affected in postnatal depression, and what the most effective treatment could be to support mothers who would like to breastfeed but are experiencing challenges.