Second-trimester maternal serum progesterone levels in Turner syndrome with and without hydrops and in trisomy 18.

Placental proteins, such as inhibin A and hCG and its subunits, as well as the placental steroid progesterone, are elevated in second-trimester maternal serum from cases of fetal Down syndrome. Since different cellular mechanisms are required for protein versus steroid synthesis and secretion, these data suggest that a generalized placental hypersecretory phenomenon is associated with Down syndrome. Inhibin A and hCG are also elevated in cases of Turner syndrome with hydrops, and are reduced in cases of Turner syndrome without hydrops and in trisomy 18. The objective of the present study was to determine maternal serum levels of the placental steroid progesterone in cases of Turner syndrome and trisomy 18. Twenty-one cases of trisomy 18, 10 cases of Turner syndrome without hydrops and 12 cases of Turner syndrome with hydrops were identified and each matched to five control samples. Maternal serum progesterone levels were significantly elevated in Turner syndrome with hydrops (2.11 MoM), slightly reduced in Turner syndrome without hydrops (0.90 MoM) and modestly, though significantly, reduced in trisomy 18 (0.73 MoM). These data are similar to the patterns seen for inhibin A and hCG, suggesting that the overall synthetic and/or secretory activity of the placenta is increased in Turner syndrome with hydrops and decreased in Turner syndrome without hydrops and in trisomy 18. These data may be helpful in understanding the pathophysiological basis of serum marker patterns in these aneuploidies.