Hb concentration and anaemia diagnostic
criteria
Capillary blood Hb concentrations were measured when
women visited the township or county hospitals during
or after pregnancy. Each woman included in the present
analysis had one Hb test in the first trimester and at least
one Hb test in each of the second and third trimesters.
Before 2000, only the lowest Hb concentration was
recorded in the woman’s health-care booklet for the PHC
surveillance system if she had more than one Hb concentration
measured in the second or third trimester. The
PHC system became electronic in 2000, and all of the Hb
concentrations were captured. To maintain consistency over
time we used the lowest Hb concentration. In accordance
with the WHO(21) and the International Nutritional Anemia
Consultative Group Steering Committee criteria(22), anaemia
in the first and third trimesters was defined as an Hb
concentration ,110 g/l, and anaemia in the second trimester