Differences in meconium stained amniotic fluid in an Australian population: A retrospective study

Background: Meconium stained amniotic fluid commonly occurs postdates (>40 weeks gestation) indicating fetal maturity. Previous literature indicates that different ethnicities mature at different rates. Aim: To compare the rate of meconium stained amniotic fluid of Australian-born and non-Australian born women. Methods: A retrospective correlation study design was implemented, using data collected in the birth outcomes system at one tertiary hospital. Data was collected from all women who gave birth to a term (>/=37 weeks gestation), singleton, liveborn baby between January 1st to December 31st, 2014. Maternal country of birth was used for comparison. Categorical data was analyzed using Chi-Square test for Independence. Continuous variables were assessed for normality, and differences were compared using an Independent t-test or a Mann–Whitney U test. All tests were two-tailed and p < 0.05 was considered statistically significant. Results: 3,041 women were included; 1131 Australian-born and 1910 non-Australian born. Meconium stained amniotic fluid occurred more frequently in non-Australian born women compared to Australian-born women (23.5% vs. 19.8 p = 0.02). Their babies were significantly smaller (Mean = 3265 g, Standard Deviation 463.8 vs Mean = 3442 g, Standard Deviation 499.2, p < 0.001), with no difference in gestational length (Mean = 39.4, Standard Deviation 1.28 vs Mean = 39.5, Standard Deviation 1.18, p = 0.06). Increasing gestational age had the strongest association with meconium stained amniotic fluid; >/=42 weeks gestation occurring 3.52 (95% Confidence Interval: 2.00, 6.22, p = <0.001) more than <40 weeks gestation. Conclusion: Maternity health services should record ethnicity and region of birth to provide individualised care as women born overseas often have poorer perinatal outcomes when compared to Australian-born women.