Late preterm infants (LPI), loosely classified by current literature as infants born 34 0/7 - 36 6/7 weeks gestation (239 days through to 259 days) [1–3], are less studied and described within Australian literature than term infants. Consensus does not exist around the gestational age group classification for this sub group of preterm infants, often cited as moderately preterm, near term, mildly preterm with gestational age ranges between 32 through to 37 weeks.
Late preterm births have contributed disproportionally to the rising incidence of preterm births within the last decade [4, 5], adding substantially to the overall impact on health care services, both in the acute, and within primary health care settings [4, 6–8]. In Australia they make up 69% of all preterm births and 8.1% of all births  and are five times more common than births occurring before 32 weeks gestation . Compared with infants born at, and within, the term gestational period (37 0/7 weeks (260 days) through to 416/7 weeks (294 days) , late preterm infants are at increased risk of neonatal morbidity, experiencing one or more short term and long term health outcomes (hypoglycaemia, hypothermia, jaundice, delayed oral feeding, readmission to hospital, transient tachypnea [1, 11], neuro-developmental delays  and mortality) [13, 14]. Despite the importance of breastfeeding for this vulnerable population of infants, the breastfeeding outcomes of preterm infants are less well documented and monitored compared to term infant populations .
The World Health Organization (WHO) recommends early initiation (where the infant receives colostrum or is breastfeed within the first hour of birth) and exclusive breastfeeding up to 6 months for all infants . Exclusive breastfeeding is the gold standard of infant nutrition, defined as the infant was fed breast milk only (including expressed breast milk, oral rehydration solutions, drops, syrups, vitamins, minerals, medicines) .
Those studies that have reported outcomes by gestational age have found that infants born at 35–36 weeks gestation are less likely to initiate breastfeeding, compared to infants born at 37–39 weeks gestation, (88.2% compared to 92.0% respectively) . Those infants born 35–36 weeks gestation had a lower incidence of breastfeeding at 6 months compared to those born ≥ 37–39 weeks . In the Pelotas birth cohort study, late-preterm infants were 10% more likely not to commence breastfeeding or receive breast milk within the first 24 hours of life than term infants .
Many factors are negatively associated with successful breastfeeding, resulting in delays in, and/or failure of, early breastfeeding initiation (within the first hour of birth) and reduced duration of exclusive breastfeeding for term infant populations including; mode of delivery (caesarean versus vaginal birth), mothers parity (primparous women), maternal smoking, insufficient milk supply, maternal obesity [20, 21]. It is therefore important to identify potential modifiable factors that contribute to breastfeeding failure (initiation and exclusive) for late preterm infants in order to customise breastfeeding support strategies that can address these factors in the clinical setting.
The aim of this study is to describe and investigate the breastfeeding outcomes of a mother and infant cohort of a sub population of preterm infants, LPI (34 0/7 - 36 6/7 weeks) compared to a 37 week gestation (37 0/7 - 37 6/7) cohort and to identify the infant and maternal factors associated with initiation and exclusive breastfeeding at discharge amongst both cohorts.