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Uterine arteries may respond more sensitively to increases in blood pressure than abdominal arteries. Researchers obtained uterine and abdominal arteries from term pregnant women and compared the contraction response of uterine muscle arteries to that of abdominal arteries. Nitric oxide inhibitors did not increase the contraction tone of arteries, suggesting that nitric oxide does not contribute to the contraction response. A drug-induced relaxation response was more pronounced in uterine than abdominal arteries. Uterine arteries may have different contraction and relaxation properties than other arteries.

Lactate levels in umbilical cord blood may indicate a lack of oxygen at birth as accurately as acid-base balance but lactate analysis may be easier. Lactate appears in blood when pH is low, as occurs with oxygen deprivation. Researchers analyzed 4,045 umbilical cord blood samples for the presence of lactate using a new electrochemical method that produces a result in one minute. Lactate levels were highest in fetuses that were delivered by cesarean section because of fetal distress. Lactate levels were much higher among vaginal deliveries than among elective cesarean sections. Neither umbilical blood acid-base measurements nor lactate measurements alone may accurately predict the neurologic outcome of newborns. The advantages of lactate analysis are its ease of use and low cost.

Introduction: There is important clinical information from placental weight and its ratio to the fetal weight. The aim with this study was to establish reference values for the placental weight and the placental:fetal weight ratio for gestational weeks 13–43 in a Swedish population.Materials and Methods: Cases were retrospectively collected from the database used at the Pathology Department at Karolinska University Hospital and information about the placental weight, fetal weight, and gestational age was retrieved. Conditions, which could affect the placental- or fetal weight were excluded. Thereafter percentile curves were calculated for the placental weight and the placental:fetal weight ratio for gestational weeks.Results: A total of 730 cases were included and percentile curves for the placental weight for gestational week 13–43 and placental:fetal weight ratio for gestational week 18–43 are presented.Conclusions: Reference values for post fixation placental weight and its ratio to fetal weight for a Swedish population are presented. The reference values are lower than the current reference values used in our institution, and this will be of importance when interpreting findings after placental examination.

This ex vivo study focuses on the mechanisms of endothelium-dependent dilatation in the uterine circulation of normal pregnancy (n = 12) and in women with preeclampsia (n = 12). Arteries (internal diameter, ∼250 μm) isolated by myometrial biopsy from women undergoing planned cesarean delivery or delivery as a result of the deterioration of preeclampsia were studied using a wire myograph. Bradykinin-induced dilatation was assessed in the presence and/or absence of pharmacological inhibitors to determine the contribution of nitric oxide and endothelium-derived hyperpolarizing factor (EDHF), as well as that of EDHF-mediated pathways such as myoendothelial gap junctions (MEGJs) and products of arachidonic acid, H2O2and cytochrome P450 2C9 (CYP2C9). Transmission electron microscopy was used to visualize morphological prerequisites for MEGJs. In normal pregnancy, EDHF through MEGJs appeared to be a predominant mediator conferring endothelium-dependent relaxation in small myometrial arteries. In preeclampsia, bradykinin-induced relaxation was reduced via compromised EDHF-type responses, in which the contribution of MEGJs became negligible. The attenuated role of MEGJs to endothelium-dependent relaxation was partly compensated through the contribution of H2O2or other endothelium-derived relaxing factors. CYP2C9 products of arachidonic acid had no effect on EDHF-type relaxation in arteries of women with normal pregnancy or with preeclampsia. We suggest that EDHF-type responses via MEGJs are primarily targeted in small myometrial arteries in women with preeclampsia. This could significantly contribute to the impaired uteroplacental blood flow in this disorder.

We investigated lactate concentrations in fetal scalp and cord blood to determine the sources of fetal lactacidosis in fetuses with ominous heart rate patterns.

To determine the effects of nitroglycerin on placental circulation in severe preeclampsia.

Objective. To compare normal pregnancy with pregnancy-induced hypertension (PIH)/preec-lampsia with respect to the effects of acute volume expansion on plasma atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP) and fetal-maternal circulation. Design. Observational study.Setting. University hospital.Subjects. Fifteen women with PIH/ preeclampsia and 15 healthy pregnant controls. Interventions. Before and after 30 minutes' infusion of a crystalloid solution (15 ml/kg), maternal venous blood was sampled for ANP and cGMP analysis and echocardiography and Doppler investigations were performed.Results. Basal median (range) ANP and cGMP levels were significantly higher in the PIH/ preeclampsia group compared to the controls: 6.5 (3.8-30.4) compared to 3.9 (2.0-6.7) pmol/1, p≤0.01 and 5.8 (2.4-11.6) compared to 4.0 (2.3-10.8) nmol/1, p≤0.05. The response to volume load was enhanced: 4.6 (-4.5-21.8) compared to 0.7 (-4.1-8.8), p≤0.05 and 2.9 (0.1-10.9) compared to 1.2 (- 5.0-6.0), p≤0.05, respectively. Systemic vascular resistance was initially higher in the patient group, 22.3 (14.1-36.7) compared to 15.6 (10.0-25.5) peripheral resistance units, p≤ 0.01 but the response to volume load was similar in both groups (12-13% decrease). The pulsatility index of the uterine artery, 0.85 (0.46-1.38) compared to 0.72 (0.49-1.26) and umbilical artery 0.89 (0.66-1.57) compared to 0.97 (0.74-1.31) did not differ between the groups. Volume expansion did not affect any of these variables.Conclusions. The pulsatility index of the uterine artery remained unaffected in both preeclamptic patients and healthy controls despite an increase of ANP and cGMP concentration and a systemic vasodilatation during acute volume expansion. This finding may indicate the absence of a vasodilatation of the uteroplacental vascular bed.

Objective: To assess the predictive value of different renal laboratory tests for development of superimposed preeclampsia in women with chronic hypertension.Methods: Thirty-seven pregnant patients with chronic hypertension and 14 healthy pregnant women were examined at 11-13,19-21, 27-29, and 31-33 weeks with the following laboratory tests: plasma concentrations of creatinine, urea and uric acid, urinary excretion of albumin, and calcium; erythrocyte excretion was investigated only at 11-13 and 27-29 weeks.Results: Among the patients who developed superimposed preeclampsia (30%), a pathologic urinary albumin excretion, i.e., microalbuminuria, was seen in 30% at 31-33 weeks pregnancy, as compared to none among patients with chronic hypertension who did not develop this complication and 7% in the normotensive women (P < 0.05, chi-square test). There was no difference between the groups at the earlier gestational ages. Plasma urea concentration tended to be lower among the normotensive women than in the other two groups only at 19-21 and 27-29 weeks (P < 0.05, P = 0.065, respectively, oneway ANOVA). Plasma urea levels tended to increase with gestational length in those with superimposed preeclampsia, whereas it decreased in the other two groups (P<0.05, ANOVA with repeated measures). The other laboratory parameters differed in no way between the three groups.Conclusion: Blood and urine sampling every 4 to 8 weeks for assessment of renal function in pregnant women with chronic hypertension seems to be of limited value for the prediction of superimposed preeclampsia.

Objective: To investigate the effect of the calcium antagonist isradipine on maternal renal Doppler blood flow indices in pregnancies complicated with hypertension.Methods: Thirty-one women with hypertension in pregnancy were consecutively recruited in an open study. Fifteen women received oral slow-release isradipine 5 mg twice daily for a 2-week period. Measurements of blood pressure and Doppler blood How velocity pulsatility index (PI) in the renal artery were obtained before treatment and were repeated 1 and 2 weeks after the treatment was started. The velocity-pressure index (VPI) was calculated as a ratio of PI and the pressure pulsatility index (PPI). A control group of 16 untreated hypertensive women was investigated in the same way.Results: In the control group blood pressure increased, while in the treatment group it decreased, giving a significant difference in percent change of mean arterial pressure between groups. The PI in the treatment group decreased significantly by 10<7r after 2 weeks, while in the control group PI did not change. There was a significant positive correlation between PPI and PI (r = 0.41. P < 0.05). The percent change in VPI from baseline was significantly different in the treatment compared to the control group.Conclusions: The finding of a decrease in both PI and VPI, together with a moderately reduced maternal blood pressure induced by isradipine, might reflect a decreased preglomerular resistance and maintained or relatively increased intraglomerular pressure. If isradipine were found to have a reno-protective effect also in pregnancy, it should not be due to the hemodynamic effects on the kidney.

To study the effects of low doses of the hormone atrial natriuretic peptide (ANP) on uteroplacental blood flow in patients with preeclampsia.

Objective.To compare normal pregnancy with pregnancy-induced hypertension (PIH)/preec-lampsia with respect to the effects of acute volume expansion on plasma atrial natriuretic peptide (ANP), cyclic guanosine monophosphate (cGMP) and fetal-maternal circulation.Design.Observational study.Setting.University hospital.Subjects.Fifteen women with PIH/ preeclampsia and 15 healthy pregnant controls.Interventions.Before and after 30 minutes’ infusion of a crystalloid solution (15 ml/kg), maternal venous blood was sampled for ANP and cGMP analysis and echocardiography and Doppler investigations were performed.Results.Basal median (range) ANP and cGMP levels were significantly higher in the PIH/ preeclampsia group compared to the controls: 6.5 (3.8–30.4) compared to 3.9 (2.0–6.7) pmol/1, p<0.01 and 5.8 (2.4–11.6) compared to 4.0 (2.3–10.8) nmol/1, p<0.05. The response to volume load was enhanced: 4.6 (4.5–21.8) compared to 0.7 (4.1–8.8), p<0.05 and 2.9 (0.1–10.9) compared to 1.2 (5.0–6.0), p<0.05, respectively. Systemic vascular resistance was initially higher in the patient group, 22.3 (14.1–36.7) compared to 15.6 (10.0–25.5) peripheral resistance units, p< 0.01 but the response to volume load was similar in both groups (12–13 decrease). The pulsatility index of the uterine artery, 0.85 (0.46–1.38) compared to 0.72 (0.49–1.26) and umbilical artery 0.89 (0.66–1.57) compared to 0.97 (0.74–1.31) did not differ between the groups. Volume expansion did not affect any of these variables.Conclusions.The pulsatility index of the uterine artery remained unaffected in both preeclamptic patients and healthy controls despite an increase of ANP and cGMP concentration and a systemic vasodilatation during acute volume expansion. This finding may indicate the absence of a vasodilatation of the uteroplacental vascular bed.

Objective: To evaluate the maternal renal hemodynamic response to acute plasma volume expansion in normal and hypertensive pregnancies, and relate it to changes in central hemodynamics and plasma atrial natriuretic peptide (ANP) concentrations.Methods: Seven women with pregnancy-induced hypertension (PIH)/ preeclampsia and 10 healthy pregnant controls in the last trimester were studied. Renal Doppler and echocardiographic investigations were performed, and maternal venous blood was sampled for determination of ANP concentrations before and after 30 min infusion of a crystalloid solution (15 mL/kg).Results: Baseline renal artery pulsatility index (PI) did not differ between the normal group (1.10 ± 0.13, mean and SD) and the PIH/preeclampsia group (1.12 ± 0.08). After volume expansion PI increased (P < 0.01) to 1.43 ± 0.23 in the normal group, but it remained unchanged in the PIH/preeclampsia group. After volume expansion, both normal and PIH/preeclamptic women showed an increase in cardiac output and stroke volume, and a decrease in total systemic resistance, while blood pressure and heart rate remained fairly unchanged. Baseline plasma concentrations of ANP before volume expansion in the normal (4.1 ± 1.3 pmol/L) and the PIH/preeclamptic (6.1 ± 3.9 pmol/L) groups did not differ significantly. Following volume expansion, concentrations of ANP increased (P < 0.05) in both groups to 6.3 ± 3.2 pmol/L and to 9.9 ± 6.1 pmol/ L, respectively. In the normal group there was a positive linear relationship between increased ANP concentrations and changes in PI (r = 0.68, P < 0.05).Conclusions: Despite similar changes in central hemodynamics and increases in plasma ANP in the two groups during volume expansion, renal vascular resistance, as estimated by renal artery pulsatility index, increased only in healthy pregnant women and not in patients with PIH/preeclampsia.

Objective. To investigate the effect of normal pregnancy and hypertensive disorders of pregnancy on the maternal renal artery Doppler blood flow velocity indices.Methods. The patient material consisted of 30 normal pregnant women, 29 women with pregnancy induced hypertension, 43 women with preeclampsia and 22 pregnant women with chronic hypertension. Blood flow velocities in the segmental renal arteries from the right kidney were analysed by pulsed and color Doppler. The systolic/diastolic (s.d.) ratio, resistance index (RI) and pulsatility index (PI) were used for Doppler waveform analysis.Results. In all of the groups of hypertensive pregnant women renal artery Doppler indices were significantly lower compared to the normal pregnant women group. There was a significant negative relationship between renal artery PI and mean arterial pressure in the preeclampsia group and in the chronic hypertension group.Conclusion. The present results demonstrate that the mechanism of renal autoregulation in preeclampsia might be altered, leaving glomerulus unprotected from increased blood pressure. It seems that the concept of renal vasoconstriction in preeclampsia might be disputed and needs further investigation.

Objective, To compare the effect of endothelin on isolated resistance arteries from different vascular beds in normal and preeclamptic women before and after pretreatment with the ETA receptor antagonist BQ-123.Materials and methods. Resistance arteries from myometrial and omental biopsies obtained at cesarean section of normal pregnant and preeclamptic women were dissected and mounted in organ baths for recording of isometric tension. The contractile response to endothelin-1 in presence and absence of BQ-123 was recorded.Results. Endothelin-1 induced similar concentration-dependent contractions in all arteries investigated. In women with preeclampsia the contractile response induced by endothelin-1 was significantly higher in omental as compared to myometrial vessels. Pretreatment with BQ-123 significantly shifted the concentration-response curve to the right but only reduced the maximum contractile response in omental vessels.Conclusion. Endothelin-1 is a potent constrictor of resistance arteries from different vascular beds in normal pregnancy and preeclampsia. The contractile effect is at least in part mediated by ETA receptors, since it was significantly reduced after pretreatment with BQ-123. In preeclamptic but not in normal pregnant women the response to endothelin-1 was reduced in myometrial as compared to omental arteries, possibly secondary to receptor down regulation.