AMBULATORY BLOOD-PRESSURE MONITORING (ABPM) IN THE NORMAL MENSTRUAL-CYCLE AND IN WOMEN USING ORAL-CONTRACEPTIVES - COMPARISON WITH CONVENTIONAL BLOOD-PRESSURE MEASUREMENT

This study was undertaken to determine if blood pressures (BP) assesse d by routine sphygmomanometry and 24 h ambulatory monitoring (ABPM) al ter throughout the normal menstrual cycle or in the cycle of women usi ng oral contraceptive pills (OCP), and the interrelationships between urinary sodium (Na) and potassium (K) excretion and ABPM throughout th e menstrual cycle. Eleven women with a normal ovulatory cycle (ovulato ry) and ten age-matched women taking an oral contraceptive pill (OCP) were studied three times in random order during their menstrual cycle, within days 1 to 5, 13 to 16, and 25 to 28. Twenty-four hour urine Na , K, and creatinine (Cr) excretion and serum Na, K, Cr, cortisol, estr adiol, progesterone and plasma renin, angiotensinogen, and aldosterone concentrations were measured. BP was measured by a mercury sphygmoman ometer and by 24 h BP (Accutracker II). On days 1 to 5, daytime systol ic BP was higher in OCP [mean: 123 mm Hg, 95% confidence interval: 117 , 128] than ovulatory women [114 mm Hg (109, 118); P.011] though dayti me diastolic BPs were similar [OCP: 71 (68, 75), ovulatory: 69(66, 72) ]. This difference in daytime systolic BP between groups was also appa rent at both of the other stages of the menstrual cycle. Nighttime sys tolic BPs were significantly higher in OCP users on days 13 to 16 (P < .05) and days 25 to 28 (p <.01). In women taking OCPs, daytime ABPM fo r days 1 to 5 were higher than their office readings by 15 (7, 23)/11 (7, 15) mm Hg (P=.001), whereas office and ABPM readings were similar in ovulatory women. This pattern was evident at all three stages. Ther e was no significant change in BP throughout the menstrual cycle withi n either group, and no correlation between urine Na or K and BP. Systo lic BPs are higher throughout the menstrual cycle in women who take OC Ps than in ovulatory women but this difference is only detected when a mbulatory blood pressure is assessed. Blood pressure does not change s ubsequently in either ovulatory or OCP-taking women throughout the men strual cycle.