Investigating the factors associated with preterm birth using evidence from the Growing Up in New Zealand cohort: a retrospective geospatial study

Background

Preterm birth (PTB) is a major public health concern with multifactorial causes. Modifiable factors, including nutrition and environmental influences, present opportunities for targeted intervention. This study examined associations between sociodemographic, nutritional, and environmental factors and PTB in a cohort of New Zealand (NZ) women.

Method

Data from 6822 mothers in the Growing Up in New Zealand cohort (2009–2010) were analysed to assess associations between sociodemographic characteristics, adherence to NZ food and nutrition guidelines, dietary patterns, micronutrient supplementation, and environmental factors (Healthy Location Index [HLI]) with PTB. Logistic and multilevel models were applied using RStudio.

Results

Of 6667 births, 436 (6.6 %) were preterm. Most sociodemographic factors, including maternal age, parity, BMI, ethnicity, and area-level deprivation, were not significantly associated with PTB. Non-adherence to breads and cereals Ministry of Health guidelines reduced odds (OR = 0.64; 95 % CI: 0.43, 0.91; p = 0.01), while a ‘Junk’ dietary pattern (OR = 1.28; 95 % CI: 1.07, 1.52; p = 0.007) and not taking iron supplements after the first trimester (OR = 1.46; 95 % CI: 1.06, 2.00; p = 0.02) increased odds. Residing in rural areas with moderate urban influence also increased odds (OR = 2.44; 95 % CI: 1.18, 4.66; p = 0.01). HLI demonstrated no significant associations.

Conclusions

Adherence to recommended food groups (breads and cereals), junk dietary patterns, low iron supplement intake after the first trimester, and rural residence with moderate urban influence were associated with increased PTB odds. Addressing maternal nutrition and geographic disparities could help mitigate this risk.