Relationship between maternal prolactin levels during pregnancy and lactation in women with pituitary adenoma

To evaluate the relationship between maternal prolactin (PRL) levels and post puerperal lactation, serum PRL levels in patients with pituitary adenoma were serially measured throughout pregnancy. The patients were divided into two groups. In patients in group 1 with complete resection of the adenoma by transsphenoidal surgery, the serum PRL level did not show a sharp rise with the onset of pregnancy as can be seen in normal pregnancy, but continued at low levels of 30ng/ml or lower until the term. In patients in group 2 who had successful pregnancies following incomplete resection of pituitary adenoma in combination with bromocriptine or bromocriptine therapy alone, high PRL levels were maintained from early in gestation until term. One out of 3 patients in group 1 showed good lactation despite low PRL levels during pregnancy. Conversely, in 22 patients in group 2 with high PRL levels during pregnancy, there were 3 patients with insufficient lactation. After suckling stimuli, the maternal PRL level did not rise in either group. These results suggest that the PRL level in maternal blood during pregnancy might not influence the amount of lactation in puerperium. In addition, an abnormally high or low PRL level during pregnancy did not affect the PRL level in cord blood or amniotic fluid or the growth of neonates.