Body size and mortality in women: a 29 year follow up of 12,000 pregnant women in northern Finland.

Abstract

STUDY OBJECTIVE: To examine the association between body height, body mass index (BMI), and mortality in fertile women of childbearing age. DESIGN: A prospective cohort study with a 29 year mortality follow up. SETTING AND PARTICIPANTS: A cohort of women (n = 11,997) expected to deliver during 1966 in two northern provinces of Finland. Data on height and pre-pregnancy weight, collected with those on sociodemographic characteristics and smoking by questionnaire at the third trimester, were provided by 91% of the participants. Follow up for mortality using national registries was from delivery until the end of 1994. MAIN RESULTS: Height had a 'U' shaped association with total mortality over the whole follow up time. In women who were shorter than average, the death rate from cardiovascular diseases was increased and in taller women this was true for tumours. Compared with the women of 'normal weight' (BMI 21 to < 25 kg/m2), the obese subjects (BMI at least 29) did not have increased mortality during the first 20 years, but had a relative risk of 1.7 during the final nine years of follow up, primarily as a result of cardiovascular diseases. The lean women (BMI < 21) experienced a similar rate overall, but moderately overweight women (BMI 25 to < 29) had a consistently lower mortality than women of normal weight. CONCLUSIONS: Among fertile women of childbearing age, both the short and tall seem to have an increased total mortality compared with those of average body height, resulting from opposite trends in major causes of death. Obesity is associated with raised long term total mortality.