Asian / Pacific Island Nursing Journal

Author ORCID Identifier

Kiyoko Mizuhata https://orcid.org/0000-0002-6198-9081

Hatsumi Taniguchi https://orcid.org/0000-0001-9999-7653

Mieko Shimada https://orcid.org/0000-0002-8165-6436

Naoko Hikita https://orcid.org/0000-0003-0395-9623

Seiichi Morokuma https://orcid.org/0000-0001-5995-0017

Corresponding Author

Mieko Shimada


Problem: The effects of breastfeeding on postpartum depression symptoms and stress using physiological measures require investigation.

Background: Breastfeeding suppresses the secretion of cortisol. Oxytocin levels correlate negatively with symptoms of postpartum depression.

Aim: To investigate the effects of breastfeeding on stress and postpartum depression.

Methods: We examined 79 breastfeeding women using the Edinburgh Postnatal Depression Scale, the Perceived Stress Scale-10, and the Breastfeeding Self-Efficacy Scale, and measured the salivary cortisol levels before and after breastfeeding.

Findings: There was a negative correlation between the duration of suckling and changes in salivary cortisol levels following breastfeeding (rs = −0.333, p < 0.05). Salivary cortisol levels immediately following breastfeeding were significantly lower compared to mothers who used mixed feeding methods p < 0.001.

Breastfeeding mothers had lower perceived stress than mothers using mixed feeding methods (β = −0.260, p < 0.05). There was no association between breastfeeding and postpartum depression; however, there was an association between postpartum depression and perceived stress (β = 0.622, p < 0.001).

Conclusion: Salivary cortisol levels significantly decreased following breastfeeding, with longer suckling times correlating with lower cortisol levels. Breastfeeding reduced stress and increased breastfeeding self-efficacy.

Declaration of Conflicting Interests

The authors declare no conflicts of interest.


This study was supported by a Grant-in-Aid for Scientific Research(B) from the Japan Society for the Promotion of Science (JSPS) (Subject No.16H05585 for Mieko SHIMADA).