Abstract:
Background: To describe breastfeeding duration indicators within a representative sample of New Zealand (NZ) infants, and investigate relationships between maternal demographics and duration of any and exclusive breastfeeding. Methods: Growing Up in NZ (GUiNZ) cohort study enrolled 6685 singletons. Breastfeeding initiation, and duration of any and exclusive breastfeeding were described for 96.3%, 91.1% and 90.3% of the singletons enrolled in GUiNZ. Multivariate Poisson regression analysis with robust variance was used to estimate the independent relationship between covariates and breastfeeding outcomes. Results: Breastfeeding was initiated for 97% of the children. Median (IQR) duration of exclusive and of any breastfeeding were 4 months (2.0-5.0) and 7 months (4.0-12.0) respectively. Exclusive breastfeeding lasted ≥4 months for 53.4% of the children and any breastfeeding for ≥6 months for 65.6% of the children. The factors independently associated to exclusively breastfeed for ≥4 months were maternal ethnicity (Māori, RR=0.80,95%CI 0.73-0.87; Pacific, RR=0.90,0.83-0.98; Asian, RR=0.80,0.74-0.86 versus European), age (20-29 years old, RR=1.24,1.04-1.49; ≥30, RR=1.36,1.14-1.62 versus <20), education (tertiary education, RR=1.14,1.08-1.21), pregnancy planning (planned, RR=1.14,1.08-1.21) or older siblings (yes, RR=1.31,1.17-1.47). The factors independently associated to breastfeed for ≥6 months were maternal age (20-29 years old, RR=1.26,1.10-1.45; ≥30, RR=1.40,1.22-1.61 versus <20), education (tertiary education, RR=1.11,1.06-1.59), pregnancy planning (planned, RR=1.11,1.06-1.15), or older siblings (RR=1.04,1.00-1.08). Conclusion: While duration of any and exclusive breastfeeding in New Zealand is longer than a number of other The Organisation for Economic Co-operation and Development (OECD) countries, a large proportion of NZ children do not achieve the World Health Organization recommendations for duration of any or exclusive breastfeeding. Maternal age, education, parity and pregnancy planning identify infants at risk of shorter duration of any and exclusive breastfeeding, and maternal ethnicity for exclusive breastfeeding only. Maternal demographics identify groups for whom breastfeeding promotion should be prioritized.