Obstetrics
Occupational fatigue and preterm premature rupture of membranes,☆☆

Presented at the Seventeenth Annual Meeting of the Society for Maternal-Fetal Medicine, Anaheim, California, October 20-25, 1997.
https://doi.org/10.1067/mob.2001.110312Get rights and content

Abstract

Objective: The aim of this study was to prospectively determine the relationship between occupational fatigue and spontaneous preterm delivery segregated 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 Prediction Study. Patients reported the number of hours worked per week and answered specific questions designed to determine the following 5 sources of occupational fatigue described by Mamelle et al: posture, work with industrial machines, physical exertion, mental stress, and environmental stress. Fatigue was quantified (0-5 index) according to the number of these sources positively reported. Simple and Mantel-Haenszel χ2 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 with a significantly increased risk of preterm premature rupture of membranes among nulliparous women but not among multiparous women. The risk of preterm premature rupture of membranes increased (P =.002) with an increasing number 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 fatigue, 5.1%; and working with 4 or 5 sources of fatigue, 7.4%. There was also a significant relationship (P =.01) between preterm premature rupture of membranes and an increasing number of hours worked per week among nulliparous women. Neither spontaneous preterm labor nor indicated preterm delivery was significantly associated with occupational fatigue among either nulliparous 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 membranes and occupational fatigue or hours worked may provide guidelines according to which nulliparous women and their employers can be advised. (Am J Obstet Gynecol 2001;184:438-46.)

Section snippets

Material and methods

The Preterm Prediction Study was a multicenter (10 sites) observational cohort study of 2929 singleton pregnancies sponsored by the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network and approved by the institutional review boards at all sites. Inclusion criteria were as follows: singleton gestation, intact membranes, and enrollment between 22 and 24 weeks’ gestation. Race and parity distributions reflected each participating center, with no single

Results

Of the 3073 women recruited for the Preterm Prediction Study, 71 were unavailable for follow-up and 73 were initially evaluated outside the gestational age window of 22 to 24 weeks’ gestation. Of the remaining 2929 women with singleton pregnancies, 1218 were nulliparous (41.6%) and 1711 were multiparous (58.4%).

The incidence of preterm delivery at <37 weeks’ gestation was 14.4% (12.6% for nulliparous women and 15.8% for multiparous women). Preterm premature rupture of membranes occurred in 4.5%

Comment

Our understanding of the relationship between employment and preterm birth remains enigmatic, despite a dramatic increase in the number of pregnant women in the American workforce. The Preterm Prediction Study was designed to identify risk factors for preterm birth in a large obstetric population with singleton pregnancies. We found that occupational fatigue and an increasing number of hours worked per week were associated with preterm premature rupture of membranes among nulliparous women

Acknowledgements

Protocol Subcommittee members are as follows: R.B. Newman, MD, R.L. Goldenberg, MD (protocol chair), A. Das, MS, A.H. Moawad, MD, J.D. Iams, MD, P.J. Meis, MD, R.L. Copper, MSN, F. Johnson, RN, E. Thom, and D. McNellis, MD. Participating members of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network are as follows: James M. Roberts, MD, Steering Committee Chair, Magee Women’s Hospital, University of Pittsburgh; John C. Hauth, MD, Robert L.

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    Supported by grants U10-HD-21410, U10-HD-27917, U10-HD-27860, U10-HD-27869, U10-HD-27905, U10-HD-27861, U10-HD-27860, U10-HD-27889, U10-HD-27883, U10-21414, and U10-HD-19897 from the National Institute of Child Health and Human Development.

    ☆☆

    Reprint requests: Roger B. Newman, MD, Department of Obstetrics and Gynecology, Medical University of South Carolina, 96 Jonathan Lucas St, Suite 634, PO Box 250619, Charleston, SC 29425.

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