Maternal obesity is associated with increased risk of gestational hypertension, preeclampsia and fetal growth restriction, complications related to reduced uteroplacental blood flow and placental vascularity malformation. T2* measurements of blood oxygen level-dependent effects have promise for assessing placental function. Here, we measured placental T2* in non-obese and obese pregnant women at 14 and 20 weeks of gestation. Our study showed that the range of placental T2* is similar between the two populations at both gestation ages. Trends of decreased and increased placental T2* with gestation were observed in different subjects, suggesting longitudinal changes in placental T2* may vary among subjects.