PHYSICAL EXERTION AS A RISK FACTOR FOR SPONTANEOUS-ABORTION

This study examined the association of physical exertion and spontaneo us abortion in a case control study of 607 women whose pregnancies end ed in spontaneous abortion and 1,287 women who delivered livebirths in Santa Clara County, CA, in 1986 and 1987. We interviewed women about the number of hours they spent doing heavy housework and caring for yo ung children. We also interviewed women employed during their pregnanc ies (71% in each group) about their work schedule; the number of hours they worked, stood, com muted, and stooped or bent; and the number of times per day they lifted weights of >15 pounds. Standing >8 hours pe r day at work was the only variable associated with increased risk [ad justed odds ratio (OR) = 1.6; 95% confidence limits (CL) = 1.1, 2.3]. This association was present only for women with a history of spontane ous abortion (adjusted OR = 2.8; 95% CL = 1.4, 5.9). Among women with this history, the OR for a second trimester abortion was 4.9 (95% CL = 1.9, 12.2). Cleaning house for >7 hours per week or caring for young children for >50 hours per week was associated with decreased risk (ad justed OR = 0.6, 95% CL = 0.5, 0.9; adjusted OR = 0.8, 95% CL = 0.6, 1 .0, respectively). Again, these associations were specific to women wi th a history of spontaneous abortion (adjusted OR = 0.4, 95% CL = 0.2, 0.7; adjusted OR = 0.5, 95% CL = 0.3, 0.8). These results indicate th at the specific type of physical exertion, the amount of exertion, and the context of the exertion may be important.