Maternal serum total activin A and follistatin in pregnancy and parturition

Objective To examine changes in maternal serum levels of activin A and foll istatin during pregnancy and labour Design In three cross sectional and three longitudinal studies venous blood was collected from women during pregnancy, spontaneous labour, labour indu ction and prior to elective caesarean section for the measurement of activi n A and follistatin. Setting Monash Medical Centre, Clayton, Victoria, Australia. Population One hundred and twenty-three women participated in a cross sectional study in pregnancy, 18 women in two longitudinal pregnancy studies, 36 women in a cr oss sectional labour study, nine women in a longitudinal study of labour in duction. Ten women undergoing elective caesarean section were also studied. Methods Activin A and follistatin were measured using two sensitive and spe cific enzyme-linked immunosorbent assays. Results In the cross sectional study of pregnancy, mean (SEM) maternal seru m activin A and follistatin levels increased towards term (2.4 ng/mL (0.3) and 1.8 ng/mL (0.3) in first trimester to 18.9 ng/mL (3.8) and 5.3 ng/mL (0 .9) at term, respectively), but the longitudinal. study revealed that level s plateau in the last three weeks of pregnancy (16.0 ng/mL (2.) and 6.2 ng/ mL (1.4) at 37 weeks and 16.6 ng/mL (3.) and 6.2 ng/mL (0.) before labour f or activin A and follistatin, respectively). There was no difference in lev els of activin A and follistatin between women delivered by caesarean secti on and labouring women at term (14.9 ng/mL (2.) vs 11.0 ng/mL (0.93) and 5. 95 ng/mL (0.67) vs 5.71 ng/mL (0.63), respectively) and levels of both prot eins did not alter throughout spontaneous or induced labour. Conclusions We believe that these data argue against activin A playing an a cute role in the initiation or regulation of human parturition.