To investigate the relationship between serum lipids and alkaline phosphata
se during normal pregnancy, we measured triglyceride, total cholesterol, HD
L-cholesterol, and LDL-cholesterol concentrations and alkaline phosphatase
activity in serum samples from 546 apparently healthy pregnant, postpartum,
and nonpregnant women. Serum HDL-cholesterol levels did not change signifi
cantly during pregnancy, but serum triglyceride, total cholesterol, LDL-cho
lesterol, and alkaline phosphatase levels increased gradually as pregnancy
proceeded, reached maximum values in the third trimester, and returned to n
onpregnant levels by 20-24 wk postpartum. The serum alkaline phosphatase ac
tivity averaged 2.1-fold higher in the late third trimester than in the fir
st trimester; the serum triglyceride concentration averaged 2.3-fold higher
in the late third trimester than in the first trimester. Compared to the p
eak values during pregnancy, serum alkaline phosphatase activity averaged 4
5% lower and serum triglyceride level averaged 47% lower at 12-16 wk postpa
rtum. The serum alkaline phosphatase activity was correlated with the serum
concentrations of total cholesterol (r = 0.68, p < 0.01) and triglyceride
(r = 0.71, p < 0.01). In short, this study shows that serum triglyceride an
d total cholesterol levels change in parallel with serum alkaline phosphata
se activity during and after normal pregnancy.