Prostaglandin metabolism in the yolk sacs of normal and diabetic pregnancies.

The malformations commonly found in fetuses of diabetic mothers occur before the 7th week of pregnancy, when fetal nutritional needs are met largely by the yolk sac. The diabetic milieu has been hypothesized to cause a disruption in the metabolism of arachidonic acid and phosphatidylinositol turnover, leading to a reduction in prostaglandin levels. In this study we evaluated how the diabetic milieu affects yolk-sac prostaglandin levels. We used ultrasound to characterize and guide aspiration of the yolk sacs of eight diabetic and 12 healthy women prior to elective abortion. In addition, we studied the yolk sacs of two healthy women in whom pregnancy termination was carried out by hysterectomy. All fetuses were between 8 and 10 weeks gestational age at the time of pregnancy termination. The yolk-sac prostaglandin E2 levels were measured using radioimmunoassay. We found that the yolk-sac diameters of diabetic women were 1.2 mm larger than those of normal women. Furthermore, the mean prostaglandin E2 level in healthy women was 3605 pg/ml, whereas prostaglandin was undetected in all the yolk sacs of diabetic women (p < 0.001). While this study suggests that defective yolk-sac metabolism of prostaglandins is one of the mechanisms responsible for diabetic embryopathy, further research is necessary to place yolk-sac enlargement and the role of prostaglandins in perspective.