妊娠阶段

SF (ug/L)

SF < 30 [n (%)]

SF < 20 [n (%)]

孕早期(n = 21)

67.1 ± 53.4

7 (33.3)

3 (14.3)

孕中期(n = 49)

26.3 ± 35.5*

40 (81.6)*

32 (65.3)*

孕晚期(n = 259)

13.2 ± 9.4*

243 (93.8)*

225 (86.9)*

F/χ²

12.097

70.359

68.292

P

0.000

0.000

0.000