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.