Objective: There is an increasing concern of anaemia in Japanese women, but no national trend data has existed to date. We analysed long-term national trends of anaemia in adult women.
Design: Secondary analyses of 15 consecutive cross-sectional nationwide surveys conducted during the period 1989-2003. Analyses were based on 5-year intervals (1989-1993, 1994-1998, 1999-2003).
Setting: Japan.
Subjects: The subjects included the National Health and Nutrition Survey of Japan (NHNS-J) population. Analyses were based on 50 967 non-pregnant/non-lactating women aged 20 years and over, with complete data sets. We stratified subjects into six age groups (20-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years and 70+ years), and three age groups (20-49 years, 50-69 years, 70+ years) for analyses on residential areas (metropolitan, cities and towns).
Results: Decreases in trends of mean haemoglobin values (intravenous) were significant in all age groups. Changes in the prevalence of anaemia were significant only in women aged 30-39 and 40-49 years. Anaemia (haemoglobin < 12.0 g dl-1) increased from 16.8% to 20.6% in women aged 30-39 years, and from 20.2% to 26.9% in women aged 40-49 years, respectively. Prevalence was highest in women aged 70 years and older in all times, but no significant change was observed.
Conclusions: Haemoglobin values have declined significantly in all ages in the last 15 years. Anaemia was especially significant in women aged 30-39 years and 40-49 years. Our findings suggest that a large number of young women in Japan are at risk of anaemia, so continuous monitoring and controlling efforts of this trend are needed.