Can prepregnancy BMI be used to detect the risk of sarcopenia in Japanese pregnant women?

BACKGROUND

More than 20% of young Japanese women fall into the category of presarcopenia (only the skeletal muscle mass is below the sarcopenia criteria), and it has recently been pointed out that thinness in young adult women may be associated with future problems related to sarcopenia (age-related muscle weakness). However, the problem of sarcopenia is related to skeletal muscle, and body mass index (BMI) cannot assess only skeletal muscle.

OBJECTIVE

Prepregnancy BMI does not assess body composition and may not adequately assess the physical health of pregnant women.

DESIGN

The study employed a longitudinal study design.

METHODS

The purpose of this study was to examine the possibility that health problems caused by sarcopenia may be overlooked if pregnant women are classified using prepregnancy BMI. Fifty-one first-time mothers without underlying medical conditions (underweight (BMI < 18.5 kg/m2, n = 8), normal weight (18.5 kg/m2 < BMI < 25 kg/m2, n = 39) and obese (25 kg/m2 < BMI < 30 kg/m2, n = 4) groups) were included. Skeletal muscle index (SMI = (two upper limb muscle mass + two lower limb muscle mass)/height2) and maximum voluntary isometric contraction of grip strength used in European and Asian sarcopenia diagnostic criteria were used to assess sarcopenia in mid- and late pregnancy.

RESULTS

For the normal-weight and underweight groups in mid- and late pregnancy, 12%-16% of participants met the diagnostic criteria for sarcopenia according to grip strength (<18 kg), 14%-26% of participants met the diagnostic criteria for sarcopenia according to the SMI (<5.7 kg/m2) and 4%-8% of participants met the diagnostic criteria for sarcopenia according to both grip strength and the SMI.

CONCLUSION

Among the pregnant women who were classified as 'normal' based on their prepregnancy BMI, 12%-26% had sarcopenia. It is therefore suggested that pregnant women's health problems could be more appropriately assessed by body composition rather than by BMI classification.