Objective: To analyze whether fetal gender affects total alkaline phosphatase (ALP) and placental ALP levels in normal pregnancy, and to determine the gestational age at which the difference occurs.
Methods: In this longitudinal study, serum total and placental ALP measurements were carried out in 30 normal pregnant women during different ranges of gestational weeks. Infant sex was recorded at the delivery for all women included in the study. Total and placental ALP levels were compared between pregnant women bearing female and male fetuses.
Results: At all gestational weeks studied, both total and placental ALP levels were higher in pregnant women carrying female fetuses than in male bearing pregnant women. Particularly, both total (260.9+/-110.2 versus 239.9+/-102.3; p=0.03) and placental (73.1+/-22.4 versus 61+/-18.2; p=0.04) ALP levels were significantly higher in the female group than in the male between 24 and 28 weeks, and the significant difference persisted between 32 and 36 weeks (p=0.02).
Conclusions: Fetal gender seems to affect total and placental ALP levels in healthy pregnant women, particularly during the second and third trimester of pregnancy. Higher ALP levels in pregnant women with female fetuses than in those with male fetuses may suggest that knowledge of the fetal gender may be in particular importance for the studies using ALP as a marker for the prediction of variety of diseases and complications seen during pregnancy.