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Background: Women using oral contraceptives have higher ambulatory blood pressures (BPs) than other women. We sought to learn whether this was associated with an alteration in the balance of angiotensin II (Ang)/Ang (1-7) and whether this ratio and BP remained constant throughout the menstrual cycle., Method: In total, 30 (15 ovulatory, 15 taking oral contraceptives) healthy, normotensive women aged 18-30 years were studied. The ovulatory group was assessed within days 1-5 (follicular phase) and 19-23 (luteal phase) and the oral contraceptive group within days 19-23. Peripheral, central and 24-h BP, vascular wall stiffness, and body composition were measured along with plasma estradiol, progesterone, renin, aldosterone, Ang II, and Ang (1-7) concentrations., Results: In ovulatory women plasma renin activity (P < 0.001), renin concentration (P < 0.01) and aldosterone (P < 0.05) were higher in the luteal than follicular phase, whereas BP, Ang II and the Ang II/Ang (1-7) ratio remained constant. In women taking oral contraceptives, plasma renin activity (P < 0.001) and concentration (P < 0.01) were higher than in follicular phase ovulatory women whereas 24-h BP, Ang II, Ang (1-7), and the Ang II/Ang (1-7) ratio (P < 0.01) were higher than in both phases of the ovulatory group. However, there was no significant correlation between BP and the Ang II/Ang (1-7) ratio., Conclusion: This study confirms that BP is constant throughout the normal menstrual cycle along with a constant balance between the vasoconstrictor (Ang II) and vasodilator [Ang (1-7)] arms of the renin-Ang-aldosterone system. Women taking oral contraceptives have a higher Ang II/Ang (1-7) ratio associated with their BP elevation although no causal relationship has been found.

Objective: To find a suitable replacement for mercury sphygmomanometry to measure blood pressure (BP) accurately in normal and hypertensive pregnancy., Methods: Two parallel validation studies were carried out in 340 pregnant women, 170 with a hypertensive disorder and 170 normotensive women. An auscultatory hybrid sphygmomanometer, A&D UM-101, and a professional automated oscillometric device for office and clinic use, Omron HEM-907, were tested. Using a modified British Hypertension Society (BHS) Protocol, nine sequential BP recordings were taken alternating between the mercury sphygmomanometer and the study device. The first readings for each device were discarded, and three differences between mercury and study device were calculated for each woman for SBP and DBP. Main outcome measures were the percentages of BP readings that were within 5, 10 and 15 mmHg absolute difference from mercury sphygmomanometry., Results: Women in both studies were an average of 34 weeks' gestation and of similar ethnicity, age and BMI. In hypertensive women, 29% had preeclampsia and 73% were receiving antihypertensives. Amongst hypertensive women, SBP was within 5 mmHg of mercury BP in 94% of readings with the auscultatory device and 75% with the automated device (P = 0.021); DBP was within 5 mmHg in 97 and 61% readings, respectively (P = 0.001). Results were similar amongst normotensive pregnant women. Both devices achieved an A/A rating according to the BHS protocol., Conclusion: The auscultatory hybrid sphygmomanometer is more accurate than the automated oscillometric device in pregnancy, specifically in hypertensive pregnancies. It is an acceptable replacement for mercury sphygmomanometry in pregnancy.

Objective: To determine whether outcomes differed for women with pre-eclampsia according to the presence of proteinuria and whether non-proteinuric pre-eclampsia is similar to gestational hypertension., Design: From 1987 to 2005, at three hospitals in Sydney, Australia, women referred to the obstetric medicine team were recruited. Outcomes for three groups were compared: proteinuric pre-eclampsia, non-proteinuric pre-eclampsia and gestational hypertension., Results: Women with proteinuric pre-eclampsia were more likely to have severe hypertension (39 versus 30%, P = 0.003), deliver preterm infants (39 versus 30%, P = 0.007) and had a higher perinatal mortality rate (25.2 versus 5.7 per 1000, P = 0.02) than those with non-proteinuric pre-eclampsia, who were more likely to have thrombocytopenia and liver disease. Women with non-proteinuric pre-eclampsia were more likely to have multiple pregnancies (3.9 versus 9.9%, P < 0.001), experience severe hypertension (8.9 versus 29.7%, P < 0.001), and deliver preterm infants (11.3 versus 30.2%, P < 0.001) who were small for gestational age (12.7 versus 20.9%, P < 0.001) than those with gestational hypertension., Conclusion: This study highlights differences between non-proteinuric pre-eclampsia and gestational hypertension. The subclassification of 'non-proteinuric pre-eclampsia' should be added to existing classification systems to alert clinicians to potential risks.

Objective: To determine whether the increase in extracellular fluid volume (ECFV) that occurs during pregnancy alters: (1) the baseline regulation of atrial natriuretic peptide (ANP); or (2) the ANP response to intravascular volume expansion with either haemaccel or hypertonic saline., Design: A group of normal pregnant subjects was studied longitudinally on three occasions, commencing before 16 weeks of gestation. They were compared with a group of age-matched non-pregnant women. Dietary sodium intake and posture were carefully controlled., Methods: Plasma volume and total ECFV were determined by tracer dilution methods, using Evans Blue and 20% mannitol, respectively. Plasma ANP and aldosterone concentrations were measured by radioimmunoassay., Results: Plasma ANP did not increase during pregnancy despite increases in both plasma and total ECFV. The plasma ANP response to acute intravenous volume expansion in later pregnancy appears to be more sensitive than either in early pregnancy or in non-pregnant subjects. The initial ANP response to infusions of haemaccel during pregnancy was greater than the ANP response to saline., Conclusions: During a normal pregnancy, plasma ANP is maintained in the normal non-pregnant range, despite an increase in plasma volume when the effects of dietary sodium intake and posture are carefully accounted for. The ANP response to intravenous volume expansion is enhanced in late pregnancy. The greater ANP response to haemaccel infusions during pregnancy suggests that an increase in atrial stretch mediates the secretion of ANP following intravenous volume expansion.

Objectives: Reduction in plasma volume (Pvol) of women with pregnancy-induced hypertension (PIH; preeclampsia) has both physiological and clinical implications. This study was undertaken to determine the following variables in women with PIH: (1) the incidence of reduced Pvol; (2) the distribution of total extracellular fluid volume (ECFV); (3) the relationship between Pvol and birth weight; and (4) whether any readily available clinical or laboratory parameters predict the presence of reduced Pvol., Setting: Teaching hospital obstetric unit and antenatal clinic., Participants: Forty-nine primigravidae with PIH (28 mild, 21 severe), 54 normotensive primigravidae and 25 non-pregnant controls., Design: Pvol was measured using Evans Blue dye and ECFV as the mannitol space. These measures were compared amongst groups, and also within groups for those with PIH, according to the severity of their disorder and the presence of proteinuria or oedema. Blood pressure, haematocrit, uric acid and serum albumin were also evaluated as predictive indices of reduced Pvol in women with PIH., Results: Pvol, ECFV and the Pvol:ECFV ratio all increased during normal pregnancy. Pvol in women with PIH was reduced compared with normal pregnancy and correlated significantly with birth weight. Total ECFV was unchanged in women with PIH, but their Pvol:ECFV ratio was significantly reduced compared with normal pregnancy. Although there was a significant correlation between Pvol and haematocrit in women with PIH, haematocrit was a poor predictor for reduced Pvol. Diastolic blood pressure greater than 100 mmHg, persistent proteinuria and severe PIH were the only reliable positive predictors of a reduced Pvol., Conclusions: Pvol is related to birth weight, but is reduced in only approximately half of women with PIH. This reduced Pvol is the result of maldistribution, not loss, of total ECFV, and can be predicted by high diastolic blood pressure, proteinuria or other clinical signs of severity, but not by haematocrit.

Twelve women in their first 3 months of pregnancy received an i.v. saline load (3 mmol sodium/kg) and a graded infusion of angiotensin II (Ang II; i.e. 4, 8 and 16 ng/kg per min). As controls, twelve comparable pregnant subjects received the saline infusion alone. Eight non-pregnant women underwent both protocols, with doses of 2, 4 and 8 ng/kg per min Ang II, and thus acted as their own controls. Saline loading evoked proportionately similar falls in basal plasma renin (PRC) and plasma aldosterone (PAC) concentrations in pregnant and non-pregnant women. Angiotensin II evoked a dose-dependent pressor response, a graded increase in PAC and a reduction in sodium and urate excretion in both pregnant and non-pregnant women. The administration of Ang II had a proportionately greater effect on sodium and urate excretion in non-pregnant than in pregnant women; the pressor response to Ang II was also decreased in the pregnant women. The stimulation of PAC by Ang II, however, did not differ between the two groups. These results show that refractoriness to the renal and vascular effects of Ang II is present as early as the eleventh week of gestation. They also support the hypothesis that there is a degree of dissociation between the renin-angiotensin system and PAC in normal pregnancy.

Many physiological variables known or thought to affect erythrocyte Na+,K+-cotransport are altered in pregnancy. The interrelationships of Na+,K+-cotransport and pregnancy were therefore examined. Values were elevated by more than 30% in both second and third trimesters with a return towards non-pregnant levels in the postpartum period. Although pregnancy was also associated with elevated plasma cholesterol, renin activity and aldosterone, there was no significant relationship within the pregnant group between Na+,K+-cotransport and any of these factors. No change could be demonstrated in Na+,K+-cotransport values after 7 days of either high (greater than 250 mmol/day) or low (less than 50 mmol/day) sodium intake and values for those who developed pregnancy-associated hypertension (PAH, pre-eclampsia) were not significantly different from those in continuously normotensive women in either the second or the third trimesters of pregnancy.