Physical load and psychological demand at work during pregnancy and preterm birth

Objectives: To evaluate the effect of physical workload and psychological d emand on all preterm births, and to determine whether these risk factors ha ve the same effect on different types of preterm birth (moderate versus ver y preterm birth) and different modes of delivery onset (spontaneous versus indicated preterm birth). Methods: A case-control study was carried out in two public general hospitals in the Valencia Region, Spain. All preterm bir ths (228) which occurred between 22 and 36 completed weeks of amenorrhea an d 348 controls of 37 or more completed weeks of amenorrhea were included. T he information was collected by interviewing women within 2 days of their g iving birth. Physical workload, psychological demand, weekly working hours and daily time spent commuting between home and work were used as explanato ry variables. A polytomous logistic regression was carried out. Results: Ex posure to medium or high level physical workload increases the risk of pret erm birth, with an adjusted odds ratio (OR) of 1.59 and 2.31, respectively. The risk of moderate preterm birth was greater in women with a medium or h igh level of physical workload, OR: 1.73 and 2.35, respectively. The same t rend was observed for very preterm birth. Physical workload showed a differ ent effect on spontaneous and indicated preterm birth. The exposure to medi um and high level physical workload increases the risk of indicated preterm birth, with an OR of 2.74 and 3.88, respectively. The same trend was seen in the case of spontaneous preterm birth. Psychological demands were not as sociated with pre, term birth. Conclusions: High physical exertion increase s the risk of preterm birth in Spain. The magnitude of the effect of physic al workload on moderate and very preterm birth is similar, but is higher on indicated preterm birth than on spontaneous preterm birth. Psychological d emands show no effect on the risk of 'preterm birth.