The objective of this study is to evaluate functional MRI as a tool to study placental transfer of oxygen and nutrients during the third trimester of pregnancy in obese women, women with pregestational diabetes and healthy low risk women without these conditions (controls). The investigators hypothesize that altered placental function, including diminished placental oxygenation and enhanced placental transport of lipids and metabolites will be seen in obese and pregestational diabetics as compared to controls.

In this study, we propose to utilize two novel and innovative non-invasive tools to measure placental oxygenation and lipid and nutrient transport in vivo in women who are obese (OB), have pregestational diabetes (DM) or have neither (controls). To evaluate differences in placental oxygenation, we propose to use Blood Oxygen Level Depending (BOLD) imaging, a method of functional magnetic resonance imaging, to measure tissue oxygenation in the placenta during the third trimester of pregnancy. To evaluate placental lipid and nutrient content, we propose to utilize Magnetic Resonance Spectroscopy (MRS), a novel and powerful tool to compare lipid and nutrient transport across the placenta among OB, DM and controls.

To confirm in vivo BOLD and MRS findings, we will extensively evaluate the placental lipid content and lipid transport capability. Fatty acid transport protein-4 (FATP-4), one of 6 FATP proteins, is important for placental lipid accumulation, especially LC-PUFA21-24. Docosahexaenoic acid (DHA) is a crucial LC-PUFA for neurogenesis in early development18. Major facilitator super family domain containing MFSD2a is a lysophospholipid transporter required for DHA uptake in the brain and has been linked to placental DHA transfer. Lipid content of the placenta can be assessed by visualizing lipid droplets via perilipin 2, the most abundant structural protein on the surface of lipid droplets of adipocytes.

We hypothesize that altered placental function including diminished placental oxygenation and abnormal placental transport of lipids and other metabolites will be seen in OB and DM women as compared to controls. We further hypothesize that ex vivo placental pathologic, histologic and immunohistochemistry characteristics will be associated with in vivo findings. Our findings from this pilot study have the potential to serve as the basis of a larger study to further evaluate the potential impact of BOLD and MRS technology on our understanding of placental lipid and oxygen transport among women with obesity and pregestational diabetes as compared to women without these conditions.

Inclusion Criteria:

• singleton pregnancy
• planned cesarean section

Exclusion Criteria:

• non-English speaking
• fetal anomalies
• gestational diabetes mellitus

Pregnant women at 30-34 weeks gestation who are scheduled for a cesarean delivery. For this pilot project, 10 obese (OB) women, 10 women with pregestational diabetes (PGD) and 10 women without OB or PGD will be recruited. OB is defined as prepregnancy or first trimester BMI greater than or equal to 30 kg/ m2. PGD will be defined as Type 1 or Type 2 diabetes diagnosed prior to the pregnancy or in the first trimester.