Large numbers of women continue to work outside the home during late pregnancy. Most research has focused on the effect of maternal work on fetal growth restriction and preterm delivery but have had conflicting results because of confounding factors. Walker and colleagues studied the influence of continued employment during pregnancy on maternal blood pressure.
The authors recruited 100 pregnant women from private practices and public clinics. The study was restricted to normotensive women with singleton pregnancies who were at 30 weeks' gestation and were employed outside the home. “Shift” and part-time workers were excluded from the study. The data collected on entry to the study included extensive information about the participants' employment and home situation, and demographic and obstetric information. Participants also rated perceived job stress on a Likert scale from zero to 5. An ambulatory blood pressure recording device provided readings every 30 minutes over two 24-hour periods. One such period was a workday, and one was a non-workday. Participants kept diaries during these periods to record activities.
The average age of the 51 primigravidas and 49 multigravidas included in the study was 32 years. The average time of gestation at monitoring was 33 weeks. The average birth weight was 3,400 g (7 lb, 7 oz), gestation at delivery was 39 weeks, and cesarean rates were 33 percent in primigravidas and 14 percent in multigravidas. No significant differences were recorded in blood pressures between the two days in post-job and sleeping times. Mean systolic and diastolic pressures, mean arterial blood pressures and mean heart rate were higher on working days and 24-hour periods when work and nonworkdays were compared. On working days, diastolic blood pressure, mean arterial blood pressure and heart rate were significantly higher during job times compared with post-job times. These results were not altered by controlling for parity or the order in which the days of monitoring were done. In the entire group, the average increase in blood pressure was small (2 to 3 mmHg), but in more than 10 percent of participants, the mean arterial blood pressure rose by 10 mmHg or more during work time. Large differences in blood pressure between the two days were associated with higher initial blood pressures, hired domestic help and greater perceived job stress.
The authors conclude that working outside the home is associated with increased blood pressure during the last trimester of pregnancy. While increases in systolic and diastolic blood pressures are of little clinical significance, work-related factors are related to increases in mean arterial blood pressure greater than 10 mmHg for 10 percent of pregnant women employed outside the home. Further, these increases appear to be more likely in women whose blood pressure is already elevated.
editor's note: Is it the work or is it the stress? We cannot be sure, but this and other studies implicate the stress. In this study, women who had domestic help showed a greater discrepancy between home and work blood pressure readings. Another study found that high blood pressure readings at home correlated with stressors such as the number of children or responsibilities for an elderly or ill relative. In the general pregnant population, the message is to reduce stress, whatever the source, and to be alert for rising blood pressure, especially in women with high baseline levels. Pregnant physicians, including residents, are an especially interesting group in regard to work-related blood pressure elevation. One study reported that 40 percent of pregnant residents demonstrated rises of at least 10 mmHg during on-call times. Another indication of the seriousness of this situation is the finding that 8.8 percent of pregnant resident physicians working long hours developed preeclampsia compared with only 3.5 percent of the wives of their male colleagues. The medical profession needs to demonstrate that stress, whatever the source, is contraindicated in pregnancy.—a.d.w.