Use of the oral contraceptive pill is associated with increased large artery stiffness in young women: the ENIGMA study

The oral contraceptive pill (OCP) is widely prescribed throughout the world. Although it is associated with a small but significant increase in blood pressure, the influence of the OCP on large artery stiffness and wave reflection is unclear. The aim of this study was to determine the relationship between use of the OCP and aortic stiffness and wave reflections in a young, healthy cohort of women.

Participants were drawn from the ENIGMA study, which examines the natural history of blood pressure in young adults. A detailed medical history and lifestyle questionnaire, including OCP details were taken. Blood pressure was measured according to the British Hypertension Society guidelines. Aortic pulse wave velocity (aPWV) was measured together with augmentation index (AIx). Stroke volume (SV) and cardiac output (CO) were also assessed.

Women taking the OCP (n = 225) had a higher SBP and pulse pressure compared with nonusers (n = 660; 112 ± 12 vs. 110 ± 11 and 43 ± 8 vs. 42 ± 8 mmHg, respectively, P < 0.05 for both). CO and SV were also higher (6.6 ± 1.5 vs. 6.3 ± 1.5 l/min, P < 0.01 and 81 ± 16 vs. 78 ± 19 ml, P < 0.05) as was aPWV (5.5 ± 0.7 vs. 5.4 ± 0.7 m/s, P < 0.05). However, there was no difference in DBP (68 ± 9 vs. 69 ± 9 mmHg), mean arterial pressure (81 ± 10 vs. 81 ± 10 mmHg) or AIx (2 ± 12 vs. 3 ± 13%) between the groups.

Use of the OCP is associated with elevated pulse pressure and SV and a small increase in aPWV in young women. The longer term implications of these effects require further investigation.