The effect of leisure time physical activity on the risk of pre-eclampsia and gestational hypertension.

STUDY
OBJECTIVE: To assess the relation between leisure time physical activity (LTPA) during the first 20 weeks of pregnancy and the risk of developing pre-eclampsia and gestational hypertension.
DESIGN: Case-control study carried out over a 28 month period with retrospective data collection.
SETTING: Six hospitals in Quebec City and four hospitals in Montreal. PARTICIPANTS: 172 women with pre-eclampsia, 254 with gestational diabetes, 505 controls. All were primiparous, with no history of high blood pressure before pregnancy (unless due to oral contraceptive use), or during the first 20 weeks of gestation. Cases were defined using recognised criteria, and 97% of those eligible agreed to be interviewed. Controls delivered in same hospital immediately after cases and had no more than one reading of elevated blood pressure during pregnancy; 96% of those eligible agreed to be interviewed.
MEASUREMENTS AND MAIN RESULTS: Participants were interviewed in hospital a few days after delivery using a questionnaire. Information was collected on type, frequency and average duration of any LTPA performed regularly during the first 20 weeks of pregnancy, together with medical, obstetric and sociodemographic details. It was found that women who performed regular LTPA had a reduced risk of pre-eclampsia (adjusted RR 0.67, 95% CI 0.46-0.96) and gestational hypertension (aRR 0.75, 95% CI 0.54-1.05), and the relative risks decreased as the average time spent in LTPA increased (aRR for pre-eclampsia among women with low, moderate and high energy expenditure: 1.00, 0.77 and 0.57, p = 0.01). The same trend was present for gestational hypertension (1.00, 0.80 and 0.71, respectively, p = 0.08).
CONCLUSIONS: Leisure time physical activity during the first half of pregnancy is likely to reduce the risk of pre-eclampsia and gestational hypertension.