Growth hormone and prolactin in maternal plasma and amniotic fluid during normal gestation

OBJECTIVE: To measure the concentration of human growth hormone (GH) and prolactin (PRL) in maternal plasma (MP) and amniotic fluid (AF) during gestation and to evaluate their correlation. METHODS: HC and PRL were measured by radioimmunoassay in 60 healthy women with uncomplicated singleton pregnancies at 16-36 weeks of gestation (WG). Trends of both hormones were estimated throughout pregnancy. The correlation of either hormone measured in different fluids was also estimated. RESULTS: GH in AF (AFGH) decreased significantly throughout pregnancy; (AF-GH = 21.32 - 0.54 X WG, r = -0.72 [95% confidence intervals (95% CI) -0.57-0.82], p = 0.001), and increased in MP (MP-GH); (MP-GH = 2.73 + 0.11 X WG, r = 0.45 [95% CI, 0.21-0.63] p = 0.05). The correlation between MP-GH and AF-GH was, (AF-GH = 16.28 - 1.54 x - M-PGH, r = -0.47 [95% CI, -0.64 -0.21]; p = 0.01). PRL values did not show significant differences neither in AF (AF-PRL / WG, r = 0.06, p = 0.6) nor in MP (MP-PRL / WG, r = 0.25, p = 0.14) during pregnancy, being AF-PRL (mean 151.3 ng/mL, SD 34.2 ng/mL) significantly higher than MP-PRL (mean 119.3 ng/mL, SD 55.4 ng/mL) (p = 0.006) in all the studied period. CONCLUSION: AF-GH and MP-GH showed a significant negative correlation during pregnancy. PRL measured in AF and PM did not show changes throughout gestation being AF-PRL significantly higher than MP-PRL.