Occupational fatigue and preterm premature rupture of membranes

OBJECTIVE: The aim of this study was to prospectively determine the relatio nship between occupational fatigue and spontaneous preterm delivery segrega ted into the etiologically distinct categories of spontaneous preterm labor , preterm premature rupture of membranes, and indicated preterm delivery. STUDY DESIGN: A total of 2929 women with singleton pregnancies at 22 to 24 weeks' gestation were enrolled in a multicenter (10 sites) Preterm Predicti on Study. Patients reported the number of hours worked per week and answere d specific questions designed to determine the following 5 sources of occup ational fatigue described by Mamelle et al: posture, work with industrial m achines, physical exertion, mental stress, and environmental stress. Fatigu e was quantified (0-5 index) according to the number of these sources posit ively reported. Simple and Mantel-Haenszel chi (2) tests were used to test the univariate association and hypothesis of a linear trend between sources of occupational fatigue and spontaneous preterm delivery. Covariables were considered by multivariate logistic regression analysis. Women who did not work outside the home were considered separately from those who worked but did not report any sources of occupational fatigue. RESULTS: Each source of occupational fatigue was independently associated w ith a significantly increased risk of preterm premature rupture of membrane s among nulliparous women but not among multiparous women. The risk of pret erm premature rupture of membranes increased (P=.002) with an increasing nu mber of sources of occupational fatigue-not working outside the home. 2.1%; working but not reporting fatigue, 3.7%; working with 1 source of fatigue, 3.2%; working with 2 sources of fatigue, 5.2%; working with 3 sources of f atigue, 5.1%; and working with 4 or 5 sources of fatigue, 7.4%. There was a lso a significant relationship (P=.01) between preterm premature rupture of membranes and an increasing number of hours worked per week among nullipar ous women. Neither spontaneous preterm labor nor indicated preterm delivery was significantly associated with occupational fatigue among either nullip arous or multiparous women. CONCLUSION: The occupational fatigue index of Mamelle et al discriminated a group of nulliparous women at increased risk for preterm premature rupture of membranes. The relationship between preterm premature rupture of membra nes and occupational fatigue or hours worked may provide guidelines accordi ng to which nulliparous women and their employers can be advised.