Testing the association between XXXX and adverse birth outcomes--design and methods.

@entity1 @entity6475 @entity285 @entity66
BACKGROUND: A number of studies have examined the effects of prenatal exposure to stress on birth outcomes but few have specifically focused on @entity6475 . In the present protocol, we aim to examine if work characterised by high demands and low control, during pregnancy, is associated with the risk of giving birth to a @entity1 born preterm or small for gestational age. METHODS AND DESIGN: We will use the Danish National Birth Cohort where 100.000 @entity1 are included at baseline. In the present study 49,340 pregnancies will be included. Multinomial logistic regression will be applied to estimate odds ratios for the outcomes: preterm; full term but small for gestational age; full term but large for gestational age, as a function of job-strain (high strain, active and passive versus low strain). In the analysis we control for maternal age, Body Mass Index, parity, exercise, smoking, @entity285 use, coffee consumption, type of work (manual versus non-manual), @entity66 and parents' heights as well as gestational age at interview. DISCUSSION: The prospective nature of the design and the high number of @entity1 strengthen the study. The large statistical power allows for interpretable results regardless of whether or not the hypotheses are confirmed. This is, however, not a controlled study since all kinds of 'natural' interventions takes place throughout pregnancy (e.g. work absence, medical treatment and job-redesign). The analysis will be performed from a public health perspective. From this perspective, we are not primarily interested in the effect of job strain per se but if there is residual effect of job strain after naturally occurring preventive measures have been taken.
