Magnetic resonance spectroscopy (MRS) can potentially be used to non-invasively measure the lipid levels in the amniotic fluid (AF), in-utero, to determine fetal lung maturity (FLM). This would eliminate the need to perform invasive and risky amniocentesis solely to determine FLM. In this study we measured the lipid to water ratio in the amniotic fluid of women with normal pregnancies. Our results showed that this ratio remained steady until after 36 gestational weeks at which point it increased exponentially. This indicates that MRS is a potential replacement for amniocentesis for estimating FLM.