What might affect hormones starting lactation?
The start of lactation after childbirth is known as ‘secretory activation’ and is initiated by hormonal changes. Secretory activation is a key determinant of successful breastfeeding with a delay in this process causing excess neonatal weight loss, often leading to increased use of formula milk and early stopping of breastfeeding.
There is limited understanding of the mechanisms mediating secretory activation in healthy, term pregnancy, but even less knowledge of how maternal and fetal morbidity may disrupt this process. This project will address biological mechanisms underlying delayed secretory activation.
The study
Delayed secretory activation is commonly caused by maternal obesity and diabetes as well as infant prematurity. Greater than 25% of all newborns worldwide are born prematurely and/or have reduced birthweight. These small vulnerable newborns (SVNs) are at increased risk of death during infant, and are likely to derive most benefit from breastfeeding which lowers infant mortality, particularly in low-incomesettings. However, milk supply is often low in mothers with SVNs, with one study reporting that ~60% of mothers with very preterm newborns (born <32 weeks) had delayed secretory activation and decreased milk production. The underlying cause is unclear. This project will investigate whether decreased exposure to lactation hormones as a consequence of shorter gestation time and/or reduced placental size impairs the mammary gland during pregnancy.
LRF-OCEHL is currently investigating how hormones induce secretory activation in mothers with healthy term infants (INSIGHT study). The aim is to generate hormone reference intervals which can be used to identify women at risk of delayed secretory activation and understand the effect of hormones on mammary gene expression, metabolism and milk composition during the early postpartum period. In collaboration with the Bode Lab, this project will extend the scope of INSIGHT to advance knowledge about the biology of delayed secretory activation with a particular focus on SVNs.
Methods
This is a longitudinal study that will build on techniques established by the INSIGHT study. This study will be sited in two centres: Women’s Centre, John Radcliffe Hospital, Oxford, UK and the Neonatal Unit, UC San Diego Health, California, USA
Mothers with preterm infants (born 24-36 weeks) or those at risk of delayed secretory activation from diseases such as diabetes, obesity or polycystic ovary syndrome will be recruited (Fig 1). With help from LRF-OCEHL research staff, we will recruit ~100 participants from the Oxford maternity and neonatal units. In parallel, the Bode team will recruit preterm mothers from the San Diego Health Neonatal Unit.
Study Team:
Bryony Davies, DPhil Candidate, NDWRH, University of Oxford, UK
Prof. Fadil Hannan, NDWRH, University of Oxford, UK (main supervisor)
Prof. Lars Bode, University of California San Diego, USA (co-supervisor)
Dr Taha Elajnaf, NDWRH, University of Oxford, UK (co-supervisor)
