THURSDAY, Dec. 8 (HealthDay News) -- Strenuous occupations don't appear to adversely affect pregnancy outcomes, but night-shift work may increase the risk of preterm delivery, according to a study published in the December issue of Obstetrics & Gynecology.
Lisa Pompeii, Ph.D., of the University of Texas School of Public Health in Houston, and colleagues studied 1,908 pregnant women between January 1995 and April 2000, and asked them to describe the physical exertion in their two longest-held jobs during pregnancy.
The investigators found that women who reported working at night had a 50% increased risk of preterm delivery, regardless of the physical exertion required. No significant effect on preterm delivery was observed in women whose jobs required them to lift repeatedly or stand for at least 30 hours per week. The findings showed that women who worked at least 46 hours per week actually had a 40% reduced risk of preterm delivery. The researchers also determined that four types of occupational exertion did not increase the risk of small-for-gestational-age births.
"Further studies are needed to determine whether uterine activity during pregnancy is influenced by melatonin, and more specifically if changes in melatonin due to shift work adversely affects pregnancy outcomes," the authors conclude.
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