Effects of maternal obesity on the placenta histología

Objectives: To determine if the histological characteristics of the terminal villi change with the increase in BMI in a full-term pregnancy.
Methods: 40 placental samples (2 mm2) were distributed into two groups: control (20) and obese (20) according to the body mass index at the beginning of pregnancy. The samples were fixed in 4% paraformaldehyde and processed using histochemical techniques. The histological slices were systematized at 10X and 40X magnifications using the Leica APERIO system and the morphometric characteristics were evaluated using the Leica´s program Byosistem IMAGESCOPE. Terminal villus density was determined by area, terminal villus area, terminal villus perimeter, terminal villus diameter, number of capillaries, Alpha Zone (number of zones), Beta Zone (number of zones), and area of fibrin.
Results: The villous area of the obese group was greater compared to control (p < 0.05). The number of capillaries (p < 0.005) and beta zones (p < 0.01) in the terminal villi from obese group were higher compared to control. Alpha zones and villous perimeter no presented differences between the groups. The fibrin in the terminal villi of the obese group was diminished compared to the control group (p < 0.0001). The number of terminal villi per mm was greater compared to the control (p < 0.0001).
Conclusion: The placenta terminal villi from obese women showed structural alterations, such as increased vascularization and villous area. Both could be a compensatory mechanism that tended to avoid a chronic hypoxic process that affected the exchange of oxygen between the mother-fetus.