Objective: To examine the effect of maternal prepregnancy overweight and obesity on gestational age-dependent variation in lipid levels during pregnancy. Methods: Women between 6 and 10 weeks of gestation who carry a single, live intrauterine pregnancy were eligible to participate in a prospective pregnancy study (N=142). The exposure, maternal prepregnancy body mass index (BMI), was classified as: normal weight (BMI 18.5-26.0 kg/m) and overweight or obese (BMI over 26.0 kg/m). Our outcomes of interest, total cholesterol, triglycerides, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol were measured at 6-10, 10-14, 16-20, 22-26, and 32-36 weeks of gestation. Mixed linear models were used to examine how the trajectory of lipid levels during pregnancy differs between overweight or obese and normal-weight women. Results: Levels of total cholesterol, triglycerides, LDL cholesterol, and HDL choloesterol increased over the prenatal period. The rate of change in LDL cholesterol (P<.001) and total cholesterol (P=.01) levels was lower for overweight or obese women than for normal-weight women in late-second and early-third trimester. As a result, overweight or obese women had significantly lower total cholesterol and LDL cholesterol levels than their normal-weight counterparts between 32-36 weeks of gestation. Conclusion: Overweight and obese women have different lipid profiles during pregnancy than their normal-weight peers. This difference may be the result of metabolic dysregulation associated with maternal overweight and obesity that mediates the increased risk of adverse outcomes found in these women.