A PROSPECTIVE-STUDY OF WORK-RELATED PHYSICAL EXERTION AND SPONTANEOUS-ABORTION

We examined the relation of physical exertion to spontaneous abortion in a prospective study of 5,144 pregnant women. In a first trimester i nterview, we obtained data on employment and physical activity at work and at home, as well as other potential risk factors for spontaneous abortion. We measured exertion as follows: time spent working, standin g and bending at work, hours between breaks, and hours spent doing hou sework or yardwork; shift worked; number of times lifted weights of mo re than 15 pounds at work or at home; number of children under age 5 y ears cared for at home. None of the exertion measures was appreciably associated with an increased risk of spontaneous abortion overall. In addition, physical activity at work and at home combined was not relat ed to increased risk. For women with a history of two or more spontane ous abortions, standing at work more than 7 hours per day was associat ed with an adjusted odds ratio (OR) of 4.3 [95% confidence limits (CL) = 1.6, 11.7], whereas standing at work for 7 hours or less was associ ated with an adjusted OR of 1.7 (95% CL = 1.1, 2.6). Women without suc h a history who stood more than 7 hours at work had an adjusted OR nea r unity.