Episodic secretion of activin A in pregnant women.

The aim of the present study was to determine the characteristics of activin A secretion in women with normal and abnormal pregnancy. With this purpose, a prospective study was done to evaluate the putative pulsatile pattern of serum activin A in serial specimens of blood collected during a certain amount of time (every 15 min for 3 h). A group of pregnant women (N = 24) participated in a cross-sectional study. They were subdivided into three groups: healthy pregnant women (N = 8), patients with preterm labor (N = 8) and patients with gestational diabetes (N = 8) before and after insulin therapy. Secretory pulses of serum activin A were determined in all patients with a specific frequency and amplitude by using two different computerized analyses, i.e. DETECT and CLUSTER. Mean +/- SEM values of serum activin A were significantly higher in patients with preterm labor and gestational diabetes than in controls (p < 0.01), showing a significant decrease following insulin therapy in diabetic patients (p < 0.01). Specific pulses of serum activin A levels were observed in all women. The mean pulse frequency did not change significantly between healthy controls and the different pathological groups. Patients with gestational diabetes after insulin therapy showed a pulse frequency that was significantly higher than in controls (p < 0.05). When the mean peak amplitude of activin A pulses was evaluated, patients with preterm labor or gestational diabetes showed values that were significantly higher than in healthy pregnant women (p < 0.01) A significant, inverse correlation between pulse frequency and amplitude was found both in healthy pregnant women (p < 0.05) and in patients with gestational diabetes (p < 0.001). The present study showed that circulating activin A levels in pregnant women change in a pulsatile pattern whose pulse amplitude is modified in the presence of gestational diseases, such as preterm labor or gestational diabetes.