The relation between maternal work, ambulatory blood pressure, and pregnancy hypertension

Study objective: The purpose of the study was to determine the relations between maternal work, ambulatory blood pressure in mid-pregnancy, and subsequent pregnancy outcome. Design: Data were studied on 933 healthy normotensive primigravidas who had been enrolled into a study on the predictive value of ambulatory blood pressure measurement performed between 18 and 24 weeks gestation. They were classified into three groups depending on whether they were at work (working group, n=245), not working (not working group, n=289), or normally employed but chose not to work (ENK group, n=399), on the day monitoring was performed. Setting: The Rotunda Hospital (a large maternity hospital), Dublin, Ireland. Main results: Adjusted for age, body mass index, smoking, drinking, and marital status, women at work had higher mean daytime systolic (p<0.01) and diastolic (p<0.01) and 24 hour systolic pressures (p=0.03) compared with those not working. The rate of subsequent development of pre-eclampsia was significantly higher (odds ratio 4.1, 95% CI 1.1 to 15.2, p=0.03) among those at work compared with those not working. The association between pre-eclampsia and maternal work remained significant (odds ratio 5.5, 95% CI 1.1 to 27.8, p=0.04) even after allowing for the confounding factors of age, smoking, body mass index, and marital status. When daytime systolic and diastolic blood pressure were added to the regression analysis the risk ratios for pre-eclampsia remained high but did not quite reach statistical significance (odds ratio 4.7, 0.90 to 24.8, p=0.066). Birth weight and placental weight were not predicted by work status or blood pressure. Conclusions: A significant independent relation was found between maternal work and ambulatory blood pressure levels in mid-pregnancy. In addition, it was found that maternal work was significantly associated with the subsequent development of pre-eclampsia.