Circulating levels of placental protein 12 (PP 12) in diabetic pregnancy complicated by retinopathy.

Placental protein 12 (PP 12) is a soluble tissue antigen. Immunohistochemical studies have localized PP 12 in the placental syncytiotrophoblast, chorion and amnion, and also in the decidua. During normal pregnancy serum-PP 12 is already raised in the first trimester, there is then a peak at 18 weeks, a gradual fall until 32 weeks, and a moderate increase thereafter. The mean of the healthy control group at 18 weeks of pregnancy was 122.9 +/- 47.5 micrograms/l. The mean of the diabetic group with retinopathy at the same time was 192.2 +/- 78.8 micrograms/l. There was no significant difference between background retinopathy and the proliferative form of diabetic retinopathy. At all times during pregnancy the median values of PP 12 in diabetic pregnancies were significantly (p less than 0.01) above the control values. Increased PP 12 levels in diabetic pregnancy complicated by retinopathy are probably caused by decidual, placental and amniotic leakages.