OBJECTIVE: To explore the relationship between blood pressure (BP) variability and perinatal outcomes. STUDY DESIGN: This was a retrospective study of 996 pregnant women with hypertension/risk factors for hypertension in pregnancy. BP variability was calculated by visit-to-visit standard deviation (SD) and mean difference (MD). Logistic regression explored the relationship between BP variability and perinatal outcome, adjusting for confounders. MAIN OUTCOME MEASURES: Correlation between BP variability and i) fetal growth restriction (FGR) and ii) preterm birth (PTB). RESULTS: FGR and PTB complicated 128/996 (13 %) and 233/996 (23 %) pregnancies. At visit 1, 61 (6 %) women were taking labetalol, 125 (13 %) were taking calcium channel blockers and 780 (78 %) were not taking antihypertensives. Increased BP variability was associated with FGR and PTB. These relationships persisted after adjustment for number of antihypertensives, pre-pregnancy BP, BMI, ethnicity and previous FGR for systolic but not diastolic BP variability (adjusted OR for FGR: 1.16 [95 % C.I. 1.03-1.30]
PTB: 1.16 [1.05-1.29]). However, statistical significance was lost after adjustment for maximum BP. Nifedipine was associated with increased BP variability, compared with labetalol, despite adjustment for ethnicity and pre-existing hypertension (adjusted difference: 1.93 mmHg [0.13-3.73], p = 0.04). CONCLUSIONS: Increased visit-to-visit systolic but not diastolic BP variability is associated with adverse perinatal outcomes. Nevertheless, it is unclear whether BP lability directly influences perinatal outcome, or merely reflects peak BP. The difference in BP variability between antihypertensives may reflect varying effectiveness or factors influencing antihypertensive choice. Prospective research is needed to investigate any potential link between antihypertensive medications, BP variability and perinatal outcome.