An updated Cochrane Review showed that maternal supplementation with omega-3 fatty acids reduced preterm birth, offering a potential strategy for prevention. We hypothesised that pregnant women with obesity, at higher risk of preterm birth, would have low omega-3 fatty acid levels and may benefit from supplementation. Our study measured the omega-3 fatty acid levels of 142 participants from the Healthy Mums and Babies study, Counties Manukau, Auckland, New Zealand. Counties Manukau is a multi-ethnic community with high rates of socio-economic deprivation, obesity, and preterm birth. Red blood cell omega-3 fatty acid levels were measured from samples collected between 12⁰ and 17⁶ weeks’ gestation. Contrary to our hypothesis, participants in our study had similar or higher levels of omega-3 fatty acids to those reported in pregnant populations in Australia, Norway, China, and Germany. Our findings emphasise the importance of testing omega-3 fatty acid status before supplementing groups at risk of preterm birth.