Potential biomarkers of preeclampsia: inverse correlation between hydrogen peroxide and nitric oxide early in maternal circulation and at term in placenta of women with preeclampsia

Preeclampsia (PE) is a pregnancy-specific disease that has been associated with future cardiovascular disease for the mother and her child. The etiology of PE is unclear but oxidative stress seems to play a major role in endothelial dysfunction and permanent systemic vasoconstriction shown in PE. Hydrogen peroxide (H(2)O(2)), a terminal metabolite of the cellular oxidative stress cascade, is also revealed as a component of oxidative ischemia/reperfusion stress in placenta. We were the first to show an increase in the levels of H(2)O(2) in the serum of preeclamptic women at term. H(2)O(2) is already known to reduce the production of NO by increasing the metabolism of arginases. The objective of this study was to investigate a possible correlation between nitric oxide (NO), a potent vasodilator, and H(2)O(2) throughout pregnancy. Thus, we simultaneously assessed the levels of NO and H(2)O(2) in the serum of normal and preeclamptic women at 10-15 and 37-40 weeks of pregnancy, and in placentas at delivery. Our findings showed an inverse correlation between increased levels of H(2)O(2) and decreased levels of NO early in maternal circulation and at term in placenta. This relationship is confirmed by our in vitro experiments which demonstrate that H(2)O(2) inhibits NO synthesis of cytotrophoblasts. In conclusion, our findings highlight an inverse correlation between H(2)O(2) and NO early in maternal circulation and in placenta of women with preeclampsia, paving the way for further studies examining the potential use of NO and H(2)O(2) as biomarkers in the prediction of preeclampsia.

Do maternal cerebral vascular changes assessed by transcranial Doppler antedate pre-eclampsia?

OBJECTIVE

To determine whether maternal transcranial Doppler (TCD) evaluation of the middle cerebral artery identifies changes in the cerebral circulation prior to the development of pre-eclampsia.

METHODS

In a nested, case-controlled study developed from a previous prospective cohort study, 20 pre-eclamptic and 40 normotensive pregnancies, matched for maternal age, were assessed with the traditional middle cerebrovascular Doppler parameters (pulsatility index, mean cerebral blood flow velocity), together with non-traditional Doppler parameters including time taken to achieve end systole (EST) and percentage time to achieve end systole (% EST). Assessments done at 20-24 and 28-32 weeks' gestational age were compared using Student's t-tests. Significance was set at the P < 0.05 level.

RESULTS

In the second trimester (20-24 weeks) there were no significant differences in any of the Doppler waveform characteristics in either group. In the third trimester (28-32 weeks) there was a significant increase in the % EST in the group who subsequently developed pre-eclampsia (45.2 +/- 4.2 vs. 42.3 +/- 4.1; P < 0.01).

CONCLUSIONS

Patients who subsequently develop pre-eclampsia show a significant lengthening in the EST in the third trimester as a late finding, which indicates an increase in the cerebrovascular resistance. Earlier prediction of pre-eclampsia using TCD waveform analysis will require more provocative testing (i.e. hand grip and CO(2) reactivity).

Chemoprevention of breast cancer. A joint guideline from the Canadian Task Force on Preventive Health Care and the Canadian Breast Cancer Initiative's Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer

OBJECTIVE

To assist women and their physicians in making decisions regarding the prevention of breast cancer with tamoxifen and raloxifene.

EVIDENCE

Systematic review of English-language literature published from 1966 to August 2000 retrieved from MEDLINE, HealthSTAR, Current Contents and Cochrane Library.

VALUES

The strength of evidence was evaluated using the methods of the Canadian Task Force on Preventive Health Care and the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer.

RECOMMENDATIONS

Women at low or normal risk of breast cancer (Gail risk assessment index < 1.66% at 5 years): There is fair evidence to recommend against the use of tamoxifen to reduce the risk of breast cancer in women at low or normal risk of the disease (grade D recommendation). Women at higher risk of breast cancer (Gail index > or = 1.66% at 5 years): Evidence supports counselling women at high risk on the potential benefits and harms of breast cancer prevention with tamoxifen (grade B recommendation). The cutoff for defining high risk is arbitrary, but the National Surgical Adjuvant Breast and Bowel Project P-1 Study included women with a 5-year projected risk of at least 1.66% according to the Gail index, and the average risk of patients entered in the trial was 3.2%. Examples of high-risk clinical situations are 2 first-degree relatives with breast cancer, a history of lobular carcinoma in situ or a history of atypical hyperplasia. As the risk of breast cancer increases above 5% and the benefits outweigh the harms, a woman may choose to take tamoxifen. The duration of tamoxifen use in such situations is 5 years based on the results from trials of tamoxifen involving women with early breast cancer. If a woman raises concerns or has already been evaluated and is calculated to be at high risk, then individuals experienced and skilled in counselling may discuss the potential benefits and harms of tamoxifen use. Important additional issues: Prevention of breast cancer with raloxifene: Current evidence does not support recommending chemoprevention of breast cancer with raloxifene outside of a clinical trial setting. Screening using the Gail risk assessment index: This index was the main eligibility criterion for enrolling women in the one study that showed potential benefit from chemoprevention. However, it has not been evaluated for use as a routine screening or case-finding instrument; validation of the index is required. Overall, current evidence does not support a shift to its routine use in physicians' offices for screening or case finding. However, when a woman or her physician is concerned about the woman's increased risk of breast cancer, the index can be a useful tool in deciding whether to pursue an in-depth discussion of the potential benefits and harms of chemoprevention. Hence, the approach to identifying women at higher risk who warrant counselling and shared decision-making will vary across practices. (The risk assessment index is available online at http://bcra.nci.nih.gov/brc/). [A patient version of these guidelines appears in Appendix 2.]

VALIDATION

The authors' original text was revised by both the Canadian Task Force on Preventive Health Care and the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer. The final document reflects a consensus of these contributors.

SPONSOR

Health Canada. COMPLETION DATE: February 2001.

[Maternal genital infections and premature delivery]

The etiology of preterm birth remains elusive being probably multifactorial. Fifty years ago, genital infection was proposed as an important risk factor. Recent advances in the identification of several pathogens together with the potential rôle of bacterial vaginosis have generated renewed interest. However may studies suffered from methodological flaws and definitive answers are yet to come. In addition, studies looking at genital infections on pathological cervices already effaced or dilated, suggested that infection may play an additive interactive role to preterm birth.

Double-blind, randomized, controlled trial of atosiban and ritodrine in the treatment of preterm labor: a multicenter effectiveness and safety study

OBJECTIVE

This study was undertaken to compare the efficacy and safety of intravenous administration of atosiban versus ritodrine for the treatment of preterm labor.

STUDY DESIGN

Women with preterm labor and intact membranes diagnosed at 23 to 33 gestational weeks (n = 247) were randomly assigned to treatment arms and received atosiban (6.75 mg intravenous bolus, 300 microg/min for 3 hours, then 100 microg/min intravenously) or ritodrine (0.10-0.35 mg/min intravenously) for as long as 18 hours. Tocolytic effectiveness was assessed in terms of the numbers of women who had not been delivered after 48 hours and after 7 days. Safety was assessed in terms of maternal side effects and neonatal morbidity. Secondary outcomes included mean gestational age at delivery and mean birth weight. An intent-to-treat analysis was performed with the Cochran-Mantel-Haenszel test.

RESULTS

The proportion of women who had not been delivered at 48 hours was 84.9% (n = 107) in the atosiban group and 86.8% (n = 105) in the ritodrine group. At 7 days 92 women had still not been delivered in both the atosiban (73.0%) and ritodrine (76.0%) groups. Neither of these differences was statistically significant. The incidence of maternal cardiovascular side effects was substantially lower in the atosiban group (4.0% vs 84.3%, P <.001). In addition, intravenous therapy was terminated more frequently as a result of maternal adverse events in the ritodrine group (29.8%) than in the atosiban group (0.8%). The overall occurrences of fetal adverse events in the two treatment groups were comparable. Neonatal morbidity was similar between the treatment groups after adjustment for unbalanced enrollment of women with multiple pregnancies and for gestational ages within treatment groups.

CONCLUSION

Atosiban was comparable in clinical effectiveness to conventional ritodrine therapy but was better tolerated than ritodrine, with no evidence of significant maternal or fetal adverse events. Neonatal morbidity, which was similar between the two treatment arms, was apparently related to the gestational age of the infant rather than to the exposure to either tocolytic agent.

Hypertension in pregnancy: new recommendations for management

Hypertension in pregnancy is a frequent complication that has substantial adverse perinatal outcomes. Hypertension may be preexisting (chronic) essential or secondary hypertension; a second entity is pregnancy induced (gestational hypertension, preeclampsia). Recent advances have identified newer markers for pregnancy hypertension: several potential candidate genes may explain the apparent family inheritance of preeclampsia, and some thrombophilic markers have been associated with the condition. Management options for mild to moderate hypertension include a short hospital stay to exclude ongoing severe hypertension and to ascertain fetal well-being. Outpatient care with appropriate maternal and fetal surveillance, including umbilical artery doppler velocimetry, is recommended for better perinatal outcomes. Acute care for severe hypertension includes the use of magnesium sulfate to prevent eclampsia and antihypertensive medication. Expeditious delivery is recommended when the maternal or fetal states cannot be stabilized. Follow-up after delivery allows the uncovering of any other coexisting hypertensive or cardiovascular disorder.

A retrospective assessment of Canadian preterm birth prevention efforts: 1979-1999

OBJECTIVES

To assess the achievements and effectiveness of efforts to reduce preterm deliveries through the collaborative efforts of funding agencies, scientists, obstetricians, pediatricians, and health care providers in Canada.

METHODS

Chronological review of studies carried out in Canada within the past two decades using several methodological approaches, including randomized clinical trials, surveys of women and physicians, and prospective cohort studies.

RESULTS

Tertiary prevention by treatment of spontaneous preterm labor with beta-agonists was effective in delaying delivery by 48 hr compared with placebo. Ongoing studies tested the comparative efficacy of oxytocin antagonists to beta-adrenergic agents. Recently, nitric oxide donors have been tested. Secondary prevention using various approaches showed that high-risk factors could not be modified by these interventions. Before applying primary prevention approaches, surveys disclosed the lack of knowledge among both physicians and pregnant women.

CONCLUSION

A recent Canadian consensus meeting emphasized the potential for success by using multidiscplinary, community-based health promotion approaches to prevent preterm labor; enhancing basic research in predictive markers such as cervical change, infection/inflammation, and psychosocial stress; and increasing political involvement of health decision makers.

Effects of smoking cessation on maternal airway function and birth weight

OBJECTIVE

To evaluate the effects of smoking cessation before or early in pregnancy on maternal airway function and birth weight.

METHODS

Measurements of forced expiratory spirometry including forced vital capacity, forced expiratory volume in 1 second, forced expiratory flow rates between 0.2 and 1.2 L, 25% and 75%, and 75% and 85%, and instantaneous flows at lung volumes of 25%, 50%, and 75% were carried out by a wedge bellow spirometer in 40 pregnant exsmokers and were compared with those of 175 nonsmoking and 97 currently smoking pregnant women. Spirometric testing was conducted at a mean (+/- SD) gestational age of 21.5 +/- 7.0 weeks. In exsmokers, the average lifetime cigarette consumption was 17.1 +/- 8.1/day for a mean duration of 9.7 +/- 3.9 years, similar to that observed in current smokers. The median duration of smoking abstinence was 20 weeks before study spirometry.

RESULTS

All spirometric measurements in exsmokers were similar to those of nonsmokers and were significantly higher than those of current smokers. Spirometric measurements for nonsmokers, current smokers, and exsmokers were respectively: forced expiratory volume in 1 second (3.36 +/- 0.39, 3.09 +/- 0.45, and 3.35 +/- 0.32 L); forced expiratory flow rate between 25% and 75% (ie, mid-expiratory phase) (3.85 +/- 0.69, 3.21 +/- 0.76, and 3.86 +/- 0.66 L/sec); forced expiratory flow rate between 75% and 85% (ie end-expiratory phase) (1.39 +/- 0.35, 1.03 +/- 0.35, and 1.41 +/- 0.39 L/sec); instantaneous flow at lung volume of 50% (4.35 +/- 0.82, 3.76 +/- 0.89 and 4.36 +/- 0.68 L/sec); and instantaneous flow at lung volume of 25% (1.91 +/- 0.47, 1.47 +/- 0.49, and 1.92 +/- 0.46 L/sec). Mean gestational age at delivery was similar among the three groups (277 +/- 11,274 +/- 12, and 274 +/- 11 days for nonsmokers, current smokers, and exsmokers, respectively). The mean birth weight of babies born to exsmokers (3408 +/- 511 g) was similar to that of babies born to nonsmokers (3469 +/- 461 g), but was significantly greater than that of babies born to smoking pregnant women (3189 +/- 485 g; P < .001).

CONCLUSION

Smoking cessation either before or at an early stage of pregnancy is associated with early, reversible increments of maternal airway function and mean birth weights that are higher than among women who continue smoking.

A prospective longitudinal study of platelet angiotensin II receptors for the prediction of preeclampsia

OBJECTIVES

We developed a simplified method using a relatively small volume of blood for the determination of platelet angiotensin II receptors by saturation analysis and we evaluated its performance for the prediction of preeclampsia.

DESIGN AND METHODS

A platelet suspension with minimal contamination by leukocytes and erythrocytes is obtained by centrifugation and washing. The platelet concentrate is incubated in a multi-well plate with increasing concentration of radiolabelled angiotensin II in the presence or absence of an excess of unlabelled angiotensin II. Bound and free fractions are separated using an oil mixture. Maximum binding is determined by Scatchard plot. This method was compared with a previously reported method. Our method was prospectively evaluated in 801 women attending our institution for routine prenatal care. A specimen was obtained at each trimester of pregnancy whenever possible. Diagnosis of preeclampsia was done postnatally by an experienced obstetrician.

RESULTS

The method showed acceptable correlation with a previously published method although a proportional bias of 2.1 was observed between the two methods. No differences in mean maximum binding were observed between normal and affected pregnancies at either trimester. Even when the results were analyzed longitudinally, using the change in maximum binding between two trimesters for each patient, no significant increase could be documented in preeclamptic pregnancies.

CONCLUSIONS

Platelet angiotensin II receptor measurement is not a clinically useful marker for the prediction of preeclampsia.

Prediction of pre-eclampsia, low birthweight for gestation and prematurity by uterine artery blood flow velocity waveforms analysis in low risk nulliparous women

OBJECTIVE

To assess the performance of four previously reported Doppler abnormalities of uterine artery velocity waveforms (presence of a protodiastolic notch, peak systolic over protodiastolic velocities (A:C ratio) > 2.5, peak systolic over end diastolic velocities (A:B ratio) > 90th centile, resistance index (RI) ([A-B]/A) > or = 0.58) in predicting pre-eclampsia, low birthweight and prematurity.

DESIGN

Prospective cohort study.

SETTING

Tertiary care university hospital in Quebec City.

POPULATION

1311 nulliparous women.

METHODS

Evaluation of pulsed Doppler abnormalities of uterine artery velocity waveforms was carried out in 1000 and 1194 of women at 18.3 (SD 0.9) or 26.7 (SD 0.9) weeks of pregnancy.

MAIN OUTCOME MEASURES

Pre-eclampsia, birthweight below the 10th centile for gestational age and spontaneous preterm birth (< 37 completed gestation weeks).

RESULTS

Pre-eclampsia, low birthweight for gestation and prematurity occurred in 4%, 11% and 7% of the pregnancies, respectively. At 26 weeks all the abnormalities of the studied Doppler indices were significantly associated with pre-eclampsia and low birthweight for gestation as reflected by the 95% confidence intervals of the positive likelihood ratios which did not include the value 1. However, sensitivities (26% to 34%) and positive predictive values (7% to 28%) were low. No Doppler indices performed significantly better than the others. The abnormalities of the Doppler indices were not associated with spontaneous prematurity. The performance of the Doppler measurements performed at 18 weeks was poor.

CONCLUSIONS

Uterine artery Doppler velocimetry waveform analysis does not qualify as a reliable screening test for pre-eclampsia or low birthweight for gestation in low risk pregnancies but may be useful in selected high risk populations.

Platelet angiotensin II binding sites and early detection of preeclampsia

OBJECTIVE

To determine if platelet angiotensin II binding density during the second or third trimester of pregnancy can be used as a marker for early detection of women who will develop preeclampsia.

METHODS

We collected blood samples from 412 nulliparous pregnant women during their second or third trimesters. They were classified in four groups after delivery: normotensive (n=297), transient hypertensive (n=54), preeclamptic (n=39), and chronic hypertensive (n=22). We also studied 35 nonpregnant women and 122 women in the peripartum period. The binding capacity of platelet angiotensin II receptors was analyzed in each patient.

RESULTS

In normotensive pregnancies, there was a significant decrease in mean (+/-standard error of the mean [SEM]) platelet binding in the second trimester (1.6+/-0.2 fmol/10(9) cells) compared with nonpregnant women (3.3+/-0.7 fmol/10[9] cells). No statistical differences were observed in the mean (+/-SEM) number of platelet angiotensin II binding sites between the groups studied in the third trimester (normal: 1.7+/-0.1 fmol/10(9) cells; transient hypertensive: 2.3+/-0.4 fmol/10(9) cells; preeclamptic: 1.6+/-0.4 fmol/10(9) cells, and chronic hypertensive: 1.6+/-0.6 fmol/10(9) cells), nor were any significant differences found in second-trimester values. At cutoff levels providing identical sensitivities, angiotensin II binding showed significantly lower positive predictive values than mean arterial pressure (P < .05). With this study's sample size, we could have demonstrated an improvement in positive predictive values of 20% with a statistical power (1-beta) of 90%.

CONCLUSION

The measurement of platelet angiotensin II receptor density cannot be recommended for the early detection of preeclampsia.

Do prostacyclin and thromboxane contribute to the "protective effect" of pregnancies with chronic hypertension? A preliminary prospective longitudinal study

OBJECTIVE

The aim of this study was to assess prospectively the urinary excretion of renal and systemic metabolites of thromboxane and prostacyclin in normotensive and chronic hypertensive pregnancies.

STUDY DESIGN

Pregnant hospital employees were invited to collect 24-hour urine samples weekly from the seventh week until delivery. Concentrations of renal metabolites (thromboxane B2, 6-keto-prostaglandin F1alpha) were measured by radioimmunoassay after extraction. Systemic metabolites (2,3-dinor-thromboxane B2, 2,3-dinor-6-keto-prostaglandin F1alpha) were assessed by enzyme immunoassay after extraction and high-pressure liquid chromatographic separation.

RESULTS

Thromboxane B2 excretion was similar in normotensive and hypertensive pregnancies, whereas a twofold increase of 6-keto-prostaglandin F1alpha was observed in hypertensive compared with normotensive pregnancies (7537 +/- 349 vs 3857 +/- 202 pg/mg creatinine, p < 0.001). During pregnancy in both conditions measurements displayed uniform excretion of thromboxane B2 with progressively increased levels of 6-keto-prostaglandin F1alpha in chronic hypertension (R2 = 0.60, p < 0.005). Mean excretion of 2,3-dinor-thromboxane B2 averaged 1208 +/- 65 and 898 +/- 48 pg/mg creatinine in normotensive and hypertensive pregnancies (p < 0.001), mainly due to significant decreased concentrations in hypertension in the first half of pregnancy. Conversely, 2,3-dinor-6-keto-prostaglandin F1alpha levels were 845 +/- 39 and 1226 +/- 67 pg/mg creatinine in normotensive and hypertensive pregnancies (p < 0.001), mostly because of significantly increased production in hypertension from 22 weeks onward. Ratios of both renal and systemic metabolites favored increased prostacyclin production in chronic hypertension.

CONCLUSION

In contrast to preeclampsia, uncomplicated mild to moderate chronic hypertensive pregnancies are characterized by an excess production of prostacyclin with unaltered or even lower thromboxane concentrations, which may contribute to the general favorable outcome of this hypertensive condition.

Report of the Canadian Hypertension Society Consensus Conference: 2. Nonpharmacologic management and prevention of hypertensive disorders in pregnancy

OBJECTIVE

To provide Canadian physicians with comprehensive, evidence-based guidelines for the nonpharmacologic management and prevention of gestational hypertension and pre-existing hypertension during pregnancy.

OPTIONS

Lifestyle modifications, dietary or nutrient interventions, plasma volume expansion and use of prostaglandin precursors or inhibitors.

OUTCOMES

In gestational hypertension, prevention of complications and death related to either its occurrence (primary or secondary prevention) or its severity (tertiary prevention). In pre-existing hypertension, prevention of superimposed gestational hypertension and intrauterine growth retardation.

EVIDENCE

Articles retrieved from the pregnancy and childbirth module of the Cochrane Database of Systematic Reviews; pertinent articles published from 1966 to 1996, retrieved through a MEDLINE search; and review of original randomized trials from 1942 to 1996. If evidence was unavailable, consensus was reached by the members of the consensus panel set up by the Canadian Hypertension Society.

VALUES

High priority was given to prevention of adverse maternal and neonatal outcomes in pregnancies with established hypertension and in those at high risk of gestational hypertension through the provision of effective nonpharmacologic management.

BENEFITS, HARMS AND COSTS

Reduction in rate of long-term hospital admissions among women with gestational hypertension, with establishment of safe home-care blood pressure monitoring and appropriate rest. Targeting prophylactic interventions in selected high-risk groups may avoid ineffective use in the general population. Cost was not considered.

RECOMMENDATION

Nonpharmacologic management should be considered for pregnant women with a systolic blood pressure of 140-150 mm Hg or a diastolic pressure of 90-99 mm Hg, or both, measured in a clinical setting. A short-term hospital stay may be required for diagnosis and for ruling out severe gestational hypertension (preeclampsia). In the latter case, the only effective treatment is delivery. Palliative management, dependent on blood pressure, gestational age and presence of associated maternal and fetal risk factors, includes close supervision, limitation of activities and some bed rest. A normal diet without salt restriction is advised. Promising preventive interventions that may reduce the incidence of gestational hypertension, especially with proteinuria, include calcium supplementation (2 g/d), fish oil supplementation and low-dose acetylsalicylic acid therapy, particularly in women at high risk for early-onset gestational hypertension. Pre-existing hypertension should be managed the same way as before pregnancy. However, additional concerns are the effects on fetal well-being and the worsening of hypertension during the second half of pregnancy. There is, as yet, no treatment that will prevent exacerbation of the condition.

VALIDATION

The guidelines share the principles in consensus reports from the US and Australia on the nonpharmacologic management of hypertension in pregnancy.

Effect of repeated freeze-thaw cycles on maternal serum biological markers for the detection of fetal trisomies

OBJECTIVES

We studied the stability of maternal blood markers for screening for Down syndrome (alpha-fetoprotein, unconjugated estriol, intact human chorionic gonadotropin (hCG) and free beta-human chorionic gonadotropin) upon repeated freeze-thaw cycles.

DESIGN AND METHODS

Forty-three samples collected from second trimester normal pregnancies were submitted to five freeze-thaw cycles. After each cycle, the markers were measured using kits and instruments from Wallac Canada (AutoDelfia). Results were compared by repeated measures analysis of variance and by analysis of linear trend (after mathematical transformation of the results in order to decrease between-sample variation) as a function of the number of freeze-thaw cycles.

RESULTS

No significant differences were observed by ANOVA (p > 0.1) for any marker. Intact hCG showed a statistically significant linear downward trend (slope = -0.0063, p = 0.009) while free beta-hCG increased (slope = 0.011, p = 0.004). After five freeze-thaw cycles, a mean decrease of 3.2% is predicted for intact hCG while free beta-hCG would increase by 5.5% on average.

CONCLUSION

We conclude that the studied markers do not show clinically significant changes under the evaluated conditions. The observed changes of intact hCG and free beta-hCG would have a limited impact on the screening performance.

Screening for Down syndrome during first trimester: a prospective study using free beta-human chorionic gonadotropin and pregnancy-associated plasma protein A

OBJECTIVES

Early screening for Down syndrome is desirable so that more time is left for intervention in the event of a positive test. In retrospective first trimester studies, maternal serum free beta-human chorionic gonadotropin and pregnancy-associated plasma protein A have been reported as useful markers. Our objective was to confirm these results in a prospective study carried on an unselected population.

DESIGN AND METHODS

In a cohort of pregnant women recruited prospectively between 9 and 13 weeks' gestation, we measured maternal free beta-human chorionic gonadotropin and pregnancy-associated plasma protein A in all affected pregnancies and 500 representative uneffected pregnancies. Serum concentrations were transformed to multiples of the median value in normal pregnancies of the same length of gestation, and rates of detection of various combinations of the markers were estimated by multivariate analysis.

RESULTS

Down syndrome was observed in 18 fetuses from the 10, 160 women recruited. Levels of free beta-human chorionic gonadotropin were elevated in affected pregnancies with an overall median value 1.8 times the median of women with normal pregnancies while pregnancy-associated plasma protein A was significantly diminished (0.51 multiples of the median). At a fixed false-positive risk of 10%, 33% (11-55), 50% (27-73), 44% (11-67), and 67% (45-89) of the affected pregnancies would have been detected (95% CI) with maternal age alone or combined with with free beta-human chorionic gonadotropin, pregnancy-associated plasma protein A or both, respectively.

CONCLUSIONS

We confirm in a prospective noninterventional study that maternal serum free beta-human chorionic gonadotropin and pregnancy-associated plasma protein A can be used in the first trimester of pregnancy to screen for Down syndrome with a performance similar to second trimester screening programs.

Early amniotomy increases the frequency of fetal heart rate abnormalities. Amniotomy Study Group

OBJECTIVE

To determine whether early amniotomy, when practised as an isolated intervention, increases the hourly rate of fetal heart rate record abnormalities.

DESIGN

This is a secondary analysis of the results of a multicentre randomised trial of early versus late amniotomy in labour.

SETTING

Secondary and tertiary level teaching hospitals.

INTERVENTION

Early amniotomy versus an attempt to conserve the amniotic membranes.

MAIN OUTCOME MEASURES

The hourly rates of early, mild variable, severe variable and late decelerations; caesarean section rates.

RESULTS

Severe variable decelerations, when classified as categorical events (> or = 1/h to 2/h, > or = 2/h to < 4/h, > or = 4/h), were more frequent in the amniotomy group (chi2 for trend = 5.7, P = 0.017). The mean hourly rates of severe variable and late fetal heart rate decelerations were increased in the amniotomy group (severe variable: amniotomy group 1.4/h, control 0.7/h, P = 0.021; late: amniotomy group 3.3/h, control 2.3/h, P = 0.011). Although the overall rate of caesarean was similar in the two groups (OR 1.2; 95% CI 0.8-1.8), there was an increase in caesarean section for fetal distress (OR 2.3; 95% CI 1.1-4.5) associated with amniotomy.

CONCLUSION

Our data suggest that early amniotomy increases the hourly rate of severe variable fetal heart rate decelerations without evidence of an adverse effect on neonatal outcome. In settings where the diagnosis of fetal compromise is based primarily on electronic monitoring, caesarean section for fetal distress may be increased by early amniotomy.

Randomized controlled trial of a prenatal vaginal birth after cesarean section education and support program. Childbirth Alternatives Post-Cesarean Study Group

OBJECTIVE

Our objective was to assess whether, for women with previous cesarean section, a prenatal education and support program promoting vaginal birth after cesarean delivery increases the probability of vaginal delivery.

STUDY DESIGN

Women with a single previous cesarean were recruited before 28 weeks' gestation. Women's self-assessed motivation to attempt vaginal birth after a previous cesarean delivery was measured on a 10 cm visual analog scale: stratum I, low motivation; stratum II, high motivation. Women were randomized by stratum to one of two groups. Those in the "Verbal" group participated in an individualized education program. Those in the "Document" group were provided with a pamphlet detailing the benefits of planned vaginal birth after cesarean delivery.

RESULTS

Rates of vaginal birth after cesarean section were similar in the verbal and document groups: verbal, 339 of 641 (53%); document, 310 of 634 (49%); relative risk 1.1, 95% confidence interval 1.0 to 1.2. There was no evidence of heterogeneity across motivational strata. Regardless of treatment group, women with low motivation for vaginal birth after cesarean section were more than three times as likely to undergo elective repeat cesarean than were women with high motivation (47% vs 13%).

CONCLUSIONS

There was no evidence that an individualized prenatal education and support program, when offered to all women with previous cesarean delivery, results in a clinically significant increase in the rate of vaginal birth after cesarean section.

Maternal hematocrit and albumin as predictors of intrauterine growth retardation and preterm delivery

OBJECTIVE

To determine if maternal hematocrit and serum albumin can predict intrauterine growth retardation and/or preterm delivery.

METHODS

Analyses were performed during each trimester of pregnancy to evaluate the predictive value of these two common laboratory parameters as predictors of intrauterine growth retardation and/or prematurity.

RESULTS

1468 women participated in the study. Intrauterine growth retardation occurred in 9.9% and preterm delivery in 6.1%. A significant inverse correlation between hematocrit and albumin and birth weight was found (r = -0.005, p = 0.04, and r = -0.07, p = 0.007, respectively), albumin being a stronger predictor as demonstrated by multiple regression. Low hematocrit at the third visit was associated with a longer pregnancy duration (r = -0.06, p = 0.02). Woman with higher serum albumin levels at the second visit, had a longer pregnancy duration, possibly reflecting a better nutritional status (r = 0.057, p = 0.03). To determine the predictive value of hematocrit and serum albumin, the prevalence of intrauterine growth retardation and premature delivery in the highest quartiles were compared with the lowest, and no significant differences were observed (p > 0.1).

CONCLUSION

Maternal hematocrit and serum albumin concentration cannot be used as useful predictors of intrauterine growth retardation or preterm delivery.

Peak systolic over protodiastolic ratio as an objective substitute for the uterine artery notch

OBJECTIVE

To measure the inter-rater agreement for the identification of a uterine artery notch, as well as the association between an observed notch and the peak systolic over protodiastolic (A/C) ratio.

DESIGN

Cohort study.

SETTING

Tertiary care university hospital.

POPULATION AND METHODS

Six hundred and sixty-five nulliparous women in whom 1022 examinations of uterine artery velocity waveforms were performed by pulsed Doppler at 18 and at 26 weeks of gestation. Agreement between two independent raters was analysed using Cohen's kappa statistics. A/C ratios of flow velocity waveforms with or without a notch were compared. The agreement between A/C values and the presence of a notch was estimated by measuring the surface under the receiver operating characteristic (ROC) curve.

RESULTS

Inter-rater agreement for the identification of a notch was 0.74 (95% CI 0.64-0.83) at 18 weeks and 0.72 (95% CI 0.64-0.80) at 26 weeks. A/C ratios were higher when a notch was present (P < 0.0001). The area under the ROC curve was 0.86 (95% CI 0.81-0.91) for the placental uterine artery and 0.93 (95% CI 0.90-0.96) for the nonplacental artery. An A/C value > or = 2.5 in any uterine artery had a sensitivity of 88% and a specificity of 86% to detect a notch.

CONCLUSION

Although there is no definitive definition of the notch, its detection is reproducible within a center. However, published prevalences between centers in unselected populations vary. The measure of the A/C ratio can serve as an objective substitute.

Is intrapartum vibratory acoustic stimulation a valid alternative to fetal scalp pH determination?

OBJECTIVES

To determine the association between fetal heart rate accelerations, whether spontaneous or induced by vibratory acoustic stimulation, and subsequent scalp pH values in presence of a suspicious intrapartum fetal heart rate tracing, and thereby assess the ability of accelerations to predict a concurrent normal fetal scalp blood pH.

DESIGN

Prospective observational study of 253 labours involving 421 pH samples.

SETTING

Tertiary care university hospital of Genoeva.

INTERVENTION

Vibratory acoustic stimulation through the maternal abdominal wall for five seconds prior to fetal blood sampling.

MAIN OUTCOME MEASURES

Spontaneous fetal heart rate reactivity (accelerations) in the 10 min preceding vibratory acoustic stimulation, vibratory acoustic-induced reactivity prior to fetal blood sampling, and scalp pH value.

RESULTS

The positive predictive value of a reactive fetal heart rate response after vibratory acoustic stimulation was 78% (95% CI 73-84%) and 97% (95% CI 94-99%) for scalp pH values of > 7.25 and > or = 7.20, respectively. Similar observations occurred with spontaneous reactivity. Of concern, 7 out of 31 (23%) occasions where the scalp blood pH was less than 7.20 appeared to be associated with a normal fetal heart rate response to vibratory acoustic stimulation.

CONCLUSION

Fetal heart rate acceleration induced by vibratory acoustic stimulation was significantly associated with a normal scalp blood pH higher than 7.25. However, vibratory acoustic stimulation offers no advantage over observation of spontaneous fetal heart rate tracings and cannot safely replace fetal blood sampling during labour.

Microalbumin as a marker of premature delivery

OBJECTIVE

To determine if microalbumin excretion can predict the development of premature delivery.

METHODS

The possibility of predicting, early in pregnancy, the development of a preterm delivery using urinary albumin was investigated in 1422 nulliparous women recruited prospectively. A first morning urine sample was collected at three occasions during pregnancy (8-14, 15-24, 25-34 weeks' gestation) for the determination of urinary albumin excretion.

RESULTS

No significant correlation was found between gestational age and urinary albumin (absolute concentration, albumin-creatinine ratio, or relative clearance of albumin) at either visit (r ranging from -0.043 to 0.036; P > .1). The incidence of preterm birth was similar for the first and fourth quartiles of the urinary albumin-creatine ratio for the second visit (5.8 and 5.7%, respectively).

CONCLUSION

Urinary albumin is not a useful marker of preterm birth in a low-risk general population.

Screening for Down syndrome during the first and second trimesters: impact of risk estimation parameters

OBJECTIVES

To evaluate impact of risk estimation parameters for screening for Down Syndrome during the first and second trimesters.

METHODS

We prospectively examined for their performance in the prenatal prediction of trisomy 21, alphafetoprotein (AFP), unconjugated estriol (uE3), total human chorionic gonadotropin (hCG), and its free subunits (free alpha-hCG, free beta-hCG) at both the first and second trimesters, and the impact of three sets of published risk estimation parameters. A total of 14,612 pregnancies were studied. All Down syndrome specimens (12 and 11 cases for first and second trimesters, respectively) and a sample of the unaffected pregnancies were analyzed.

RESULTS

The median multiple of median (MoM) for total hCG was lower in the first trimester (1.83 vs. 2.01 in the second trimester) but no loss in discriminative power was observed if the lower variability of the results in the first trimester is taken into account (interquartile range of 0.251 vs. 0.338). The choice of distribution parameters did not alter significantly the detection rates for the various combinations of markers (p > 0.05). False positive rates were affected significantly however and for the combination AFP-uE3-free beta-hCG they varied from 14.6% to 22.6% (p < 0.001).

CONCLUSIONS

Our results suggest that specific distribution parameters would be necessary to account for the lower variability of the markers in the first trimester and the peculiarity of the total hCG assay we used.

Development of an enzyme-linked immunosorbent assay for 2,3-dinor-6-keto-prostaglandin F1 alpha in urine using a monoclonal antibody

OBJECTIVES

To develop and validate an enzyme-linked immunosorbent assay (ELISA) for measurement of urinary 2,3-dinor-6-keto-prostaglandin F1 alpha (2,3D6KPGF1 alpha) using a monoclonal antibody and a horseradish peroxidase-linked antigen.

DESIGN AND METHODS

Assay validation included optimization of the standard curve, antibody cross-reactivity, accuracy and imprecision studies together with preliminary measurement of clinical samples.

RESULTS

Optimal conditions of the standard curve (0.078-10.0 micrograms/L) used 2 mg/L of antibody and 3 micrograms/L of peroxidase conjugate in each well, at pH 7.2. The coefficient of variation of various concentrations of the standard curve averaged 6.8%. Antibody cross-reactivity was < 0.01% for related prostanoids. Recovery of known amounts (0.1-5.0 micrograms/L) of 2,3D6KPGF1 alpha added to an urinary sample was 101.2 +/- 6.3%. Imprecision studies with non-pregnant (0.24 microgram/L) and pregnant (2.5 micrograms/L) samples displayed an intraassay variability of 8.9 and 9.9%, and an interassay variability of 9.6 and 10.0%, respectively. Urinary measurements in the non-pregnant and pregnant states were similar to those previously reported. An apparent decreased concentration was observed early in pregnancy in future preeclampsia.

CONCLUSION

With similar precision and validity, our assay method is time- and cost-saving. Preliminary urinary measurements show that this analyte may be of interest as an early marker for preeclampsia.

Increased immunohistochemical expression of neutral metalloendopeptidase (enkephalinase; EC 3.4.24.11) in villi of the human placenta with pre-eclampsia

The purpose of this study was to identify the presence of placental neutral metalloendopeptidase (NEP; enkephalinase; EC 3.4.24.11) in human normotensive and pre-eclamptic pregnancy. The localization of NEP in placentae from normotensive, chronic hypertensive and pre-eclamptic pregnancies was carried out on fresh frozen tissues by using a monoclonal primary antibody developed against human common acute lymphoblastic leukaemia antigen (CD10) together with the avidin-biotin-peroxidase method. In placentae from normotensive, chronic hypertensive and superimposed pre-eclamptic pregnancies, intense staining was found in the extravillous trophoblast, and also in fibroblasts of the chorionic plate and stem villi. Light to moderate staining was noted in the villous-associated trophoblast and in some cells from the villous core. In cases of pre-eclampsia, very intense staining was detected not only on the surface, but also in the cytoplasm of the villous-associated trophoblast. The increased expression of placental NEP in pre-eclampsia suggests that this enzyme may be involved in the regulation of the local concentration of circulating biologically active peptides at the fetomaternal interface, and thus could be implicated in the pathophysiological changes of this syndrome.

Randomised comparison of amoxycillin and erythromycin in treatment of genital chlamydial infection in pregnancy

Erythromycin, the standard treatment for chlamydial infection in pregnant women, commonly causes side-effects, which limits its efficacy. In a randomised, double-blind study, we compared amoxycillin with erythromycin in this setting. 210 pregnant women with Chlamydia trachomatis infection were randomly assigned 7 days' treatment with amoxycillin (500 mg three times daily) or erythromycin (500 mg four times daily). Control cultures were obtained 21 days after treatment, during late pregnancy, and from the infant within a week of birth. Treatment was judged a failure if any post-treatment culture was positive or if the patient had to stop therapy because of severe side-effects. 11 women (5.2%) were lost to follow-up. 1 (of 100) amoxycillin-treated women had to stop treatment because of severe side-effects compared with 12 (of 99) erythromycin-treated women (p = 0.002). 1 woman in the amoxycillin group had a positive culture at the third-trimester examination. No positive post-treatment culture was found in the erythromycin group. Severe gastrointestinal side-effects were more common in women who received erythromycin (31 vs 6%, p < 0.001). The overall failure rate was therefore 2% in the amoxycillin group and 12% in the erythromycin group (p = 0.005). These results suggest that amoxycillin is an acceptable alternative to erythromycin for C trachomatis infection in pregnant women.

Effects of prostaglandin inhibition on the renal function curve during ovine pregnancy

OBJECTIVE

This study was designed to assess the influence of prostaglandins on the steady-state relationship of mean arterial pressure and urinary sodium excretion.

STUDY DESIGN

Ten nonpregnant and nine pregnant ewes were chronically prepared with indwelling catheters and maintained in metabolism cages. All the ewes received a continuous intravenous infusion of indomethacin (5 mg/kg/day) for 24 days. Step increases in sodium intake (20, 100, 400, and 1200 mmol per day), each maintained for 6 days, were administered as a fixed dietary (20 mmol) component with the balance infused intravenously. Mean arterial pressure was continuously monitored. The renal function curves were constructed from the steady-state mean arterial pressure-urinary sodium excretion relationships after sodium balance was attained.

RESULTS

Indomethacin inhibited urinary excretion of prostaglandin E2 by 62% +/- 4% in nonpregnant and 47% +/- 6% in pregnant ewes, and 6 keto-prostaglandin F1 alpha, the stable metabolite of prostaglandin I2, by 55% +/- 4% and 65% +/- 6% in nonpregnant and pregnant ewes, respectively. Blood volume was not affected by indomethacin or salt in either group. Plasma angiotensin II was suppressed less in pregnant ewes (60% vs 80%) by increases in salt intake. Chronic treatment with indomethacin did not alter the renal function curves of either nonpregnant or pregnant ewes.

CONCLUSIONS

These results suggest that prostaglandins do not influence the steady-state relationship between mean arterial pressure and urinary sodium excretion in either nonpregnant or pregnant sheep.

Electrophoretic method for separating small peptides in serum without extraction of macromolecules: application to the detection of preeclampsia

We optimized the electrophoretic separation using sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE) and silver staining to detect small peptides in serum, without extraction of major proteins and applied this method to the search for specific peptides that may be used as early markers of preeclampsia during pregnancy. Appropriate separation of peptides was possible by modifying several parameters: increasing total proportion of monomers (%T) from 3 to 5% in the stacking gel; decreasing total proportion of crosslinker (%C) from 2.7 to 1.5% in the separating gel; selecting alkaline stacking gel buffer (pH 8.8) and alkaline sample buffer (pH 8.0); adding glycerol to both gels; and processing with weak current (15 mA). Silver nitrate staining was improved by using glutaraldehyde as the fixing agent, by reducing cross-linker concentration and by eliminating oxidizing and reducing agents. Sensitivity of the improved silver nitrate staining was 50 ng. We compared the electrophoretic pattern of serum peptides in the range of 2-14 kDa of 20 preeclamptic women with and without proteinuria and of 25 women in their third trimester who later developed preeclampsia to that of 24 normal pregnant women at term. No differences were found in the electrophoretic patterns among the groups and there was no correlation between the intensity of the bands and the severity of preeclampsia. We conclude that there is no characteristic electrophoretic pattern associated with preeclampsia.

Platelet-induced vasomotion of isolated canine coronary artery in the presence of halothane or isoflurane

To determine the effect of 1.5 MAC of two volatile anesthetics (halothane and isoflurane) on platelet-induced contraction of canine coronary artery, isolated, denuded coronary rings were suspended between two stirrups, placed into organ chambers filled with an oxygenated Krebs-Ringer solution, and connected to an isometric force transducer. Human platelets were obtained from healthy donors and introduced into the organ chambers in increasing amounts to reach 20,50 and, 70 x 10(9) platelets/L. The tension generated in both the control and anesthetic-treated rings was recorded; only halothane reduced the tension induced by platelet activation in the organ chambers. In some experiments, aliquots of Krebs-Ringer solution were taken to determine the amount of 5-HT and TB2 released by 70 x 10(9) human platelets in the presence and absence of the anesthetics. Only halothane reduced TA2 production by the activated platelets. Finally, the contractile response of isolated denuded canine coronary artery rings to U46619, a thromboxane analog, was measured in the presence and absence of the anesthetics. Neither halothane nor isoflurane attenuated the response. In another series of experiments, in vitro platelet aggregation was induced by epinephrine, collagen, ADP, or arachidonic acid in the presence or absence of 1.5 MAC isoflurane or halothane. Both anesthetics significantly reduced the aggregation.

A prospective study of several potential biologic markers for early prediction of the development of preeclampsia

OBJECTIVE

The purpose of this study was to prospectively evaluate the predictive performance of several potential biologic markers of preeclampsia used alone or in combination.

STUDY DESIGN

A prospective cohort of 1366 nulliparous women was followed up longitudinally on three occasions during pregnancy. The predictive performance of the tests, used either alone or in combination (stepwise multiple logistic regression), was assessed and compared with that of the mean arterial pressure.

RESULTS

Preeclampsia occurred in 109 of the pregnant women. At a specificity of 80% the sensitivity and the positive and negative predictive values for mean arterial pressure (at a threshold of 87 mm Hg) were 46.6%, 23.5%, and 92.0%, respectively, and the corresponding values for a multiple logistic model at 15 to 24 weeks that included some biologic markers, as well as the mean arterial pressure, were 57.1%, 26.9%, and 93.7%, respectively.

CONCLUSION

Preeclampsia can be predicted by a combination of simple biologic tests with a performance similar to second-trimester mean arterial pressure. However, this procedure is insufficient in terms of clinical usefulness.

[Pregnant women's knowledge of prematurity in Quebec]

The objective of this study was to determine pregnant women's knowledge level concerning premature birth. During July of 1990, 465 pregnant women completed a questionnaire evaluating their knowledge of the following dimensions of premature birth: risk factors, symptoms, epidemiology, prevention and self-assessment of risk. The subjects were all francophones, at 16 weeks of less of pregnancy, with characteristics comparable to all pregnant women in Quebec. The study participants considered premature birth to be a serious health problem, and over-estimated the premature birth rate. Fifty-seven percent thought that the rate was 17% or greater. Eighty percent associated premature birth with some morbidity and mortality risks. On the other hand, the risk factors concerning premature birth were poorly known; approximately 50% of the women did not recognize twin pregnancy and a past history of premature delivery as risk factors. Moreover, a third of the women did not recognize the signs and symptoms of premature rupture of membranes and of premature labor. In conclusion, a high proportion of pregnant women in Quebec do not have even minimally adequate knowledge levels concerning the prevention or risks of premature birth.

Strategy for screening pregnant women for chlamydial infection in a low-prevalence area

OBJECTIVE

To assess the prevalence and risk factors for chlamydial infection in pregnant women in the Quebec City area and to propose strategies for a screening program.

METHODS

From January 1990 to July 1991, pregnant women from six centers were cultured for Chlamydia trachomatis. One hundred thirty-six with positive results and 536 with negative results were included in a case-control study on risk factors for this infection.

RESULTS

The prevalence of C trachomatis was 1.9% (136 of 7305). In a logistic regression analysis, young age (P < .0001, test for trend), nulliparity (odds ratio [OR] 3.3; P < .00001), and a new sexual partner in the last year (OR 3.3; P = .0012) were independently associated with infection. With screening restricted to pregnant women under age 25 or those with at least one risk factor, 81.7% of women positive for C trachomatis would have been detected, whereas only 40.6% of all women would have been cultured.

CONCLUSION

In a low-prevalence area for chlamydial infection in pregnant women, pre-screening criteria could optimize the use of specific diagnostic tests.

Effect of early amniotomy on the risk of dystocia in nulliparous women. The Canadian Early Amniotomy Study Group

BACKGROUND

Early amniotomy has been advocated as a means of preventing dystocia, but its efficacy has not been studied prospectively. The purpose of this multicenter study was to determine whether routine early amniotomy reduces the risk of dystocia for nulliparous women in spontaneous labor.

METHODS

We studied 925 nulliparous women in labor, who were stratified according to the degree of cervical dilatation (< 3 cm vs. > or = 3 cm) and randomly assigned to either early rupture of the membranes (amniotomy group) or conservative management of labor (conservative-management group). Dystocia was defined as a period of at least four hours after dilatation of the cervix to 3 cm had been reached during which the mean rate of cervical dilatation was less than 0.5 cm per hour.

RESULTS

Dystocia was significantly less frequent in the amniotomy group than in the conservative-management group (34 percent vs. 45 percent; relative risk, 0.8; 95 percent confidence interval, 0.6 to 0.9). The median length of time from randomization to full dilatation was 136 minutes shorter in the amniotomy group, and there was a trend toward less frequent use of oxytocin among the women assigned to amniotomy (36 percent vs. 41 percent; relative risk, 0.9; 95 percent confidence interval, 0.8 to 1.0). In a stratified analysis, the frequency of dystocia associated with amniotomy was reduced only among women with > or = 3 cm initial dilatation. The cesarean-section rate was similar in the two groups (amniotomy, 12 percent; conservative management, 11 percent). There were no statistically significant differences in outcome between the infants delivered by the women in the two groups; the measures of an adverse outcome included admission to a neonatal intensive care unit, five-minute Apgar score below 7, and arterial cord-blood pH below 7.2.

CONCLUSIONS

Early amniotomy is an effective method of shortening the duration of labor and reducing the frequency of dystocia among nulliparous women in labor, but it does not lower the rate of cesarean section.

Multicentre collaboration in perinatal trials in Canada

From a request of the Ministry of Health, the Canadian Association of Professors of Obstetrics and Gynecology and the Medical Research Council played a leadership role in convening perinatal investigators of all 16 university departments. The consensus was reached that the best means to improve the health of Canadians was to treat and/or prevent prematurity. In the last 10 years, several multicentre clinical trials were designed and carried out on perinatal interventions. This multicentre Canadian collaboration has recently evolved in the formation of a permanent perinatal clinical trial network of more than 100 members.

Effect of cigarette smoking on maternal airway function during pregnancy

The effects of cigarette smoking on maternal airway function during pregnancy were investigated in a cross-sectional study of 97 smokers and 175 nonsmokers at different gestational ages. The groups were comparable in age, height, and weight. All subjects were healthy. Forced vital capacity, forced expiratory volume in 1 second, their ratio, the forced expiratory flow rates between 0.2 and 1.2 L, 25% and 75%, and 75% and 85%, and instantaneous flows at lung volumes of 25%, 50%, and 75% were measured. All spirometric tests were unaffected by gestational age. However, all parameters of spirometry were significantly less in smokers than in nonsmokers when cumulative data during pregnancy were compared. Forced vital capacity, forced expiratory volume in 1 second, and their ratio were minimally reduced (4%, p less than 0.05; 8%, p less than 0.001; and 4%, p less than 0.001; respectively) in smokers as compared with nonsmokers. Larger reductions were noted in forced expiratory flow rates between 0.2 and 1.2 L (14%, p less than 0.001) and between 25% and 75% (16%, p less than 0.001), and in instantaneous maximum flows at lung volumes of 75% (11%, p less than 0.001) and 50% (13%, p less than 0.001). Maximum reduction of forced expiratory flow rates between 75% and 85% (26%, p less than 0.001) and in instantaneous flows at maximum lung volumes of 25% (23%, p less than 0.001) suggests marked increases in small-airway resistance and early small-airway disease in smokers. The progression of small-airway disease is related to the level of cigarette exposure. The results of our study demonstrate that the bronchodilatory effect expected in pregnancy is not sufficient to overcome the deleterious effects of cigarette smoking.

Twin pregnancy: the impact of the Higgins Nutrition Intervention Program on maternal and neonatal outcomes

Perinatal outcomes were compared between 354 twins treated with the Higgins Nutrition Intervention Program and 686 untreated twins. After differing distributions of key confounding variables were adjusted for, the twins in the intervention group weighed an average of 80 g more (P less than 0.06) than the nonintervention twins; their low-birth-weight rate was 25% lower (P less than 0.05) and their very-low-birth-weight rate was almost 50% lower (P less than 0.05). Although the rate of preterm delivery was 30% lower in the intervention group (P less than 0.05), the rates of intrauterine growth retardation were similar in the two groups. Fetal mortality was slightly higher (14 vs 12 per 1000, NS), but early neonatal mortality was fivefold lower (3 vs 19 per 1000, P less than 0.06) in the intervention group. Maternal morbidity was significantly lower (P less than 0.05) in the intervention group. There was a trend towards lower infant morbidity in the intervention group. These results suggest that nutritional intervention can significantly improve twin-pregnancy outcome.

[Preeclampsia: physiopathology and prospects for early detection]

Preeclampsia is a complication of pregnancy characterized by hypertension, edema and proteinuria, beginning after 20 weeks of gestation. Six percent of the pregnant women in North America develop this disease, which is associated with increased morbidity and mortality for the mother and her baby. The physiopathology remains uncertain despite many research efforts. Actual hypotheses seek to explain the vasospasm that characterizes the disease. Among the many factors influencing vascular reactivity and possibly implicated are: the renin-angiotensin system, prostaglandins, progesterone and its metabolites, calcium, magnesium, digoxin-like immunoreactive substance(s), auricular natriuretic factor, substances secreted by platelets and leukotrienes. Prevention of the disease is limited by the absence of a biological or clinical marker with good sensitivity and appropriate specificity. Many biochemical or hematological parameters have been reported: uric acid, calcium, magnesium, proteinuria, blood iron, hematocrit, platelet count, antithrombin III, estrogen and progesterone. The combination of several tests could be superior to the use of each test individually, providing a better sensitivity and improving the positive predictive value. With early detection, new therapies for the prevention of the disease could be experimented on the higher risk women before the apparition of clinical symptoms or signs. Furthermore, those tests could be used in the study of the pathophysiology and in the choice of the best therapy.

Maternal and neonatal outcome in pregnancies with no risk factors

Between November 1979 and April 1984, 790 consecutive pregnant women who considered themselves as having a "normal" pregnancy were followed in private practice from 9 weeks' gestation until 6 weeks post partum. The women had no pre-existing disease or problem classified as a risk to the pregnancy at the time of their first visit, had a singleton pregnancy and gave birth at Notre-Dame Hospital, Montreal. Maternal complications occurred during the course of pregnancy in 181 women (23%). Complications were mostly related to obstetric conditions (10%), such as preterm labour, intrauterine growth retardation (IUGR) and antepartum hemorrhage, or to medical conditions (12%), the most prevalent of which was hypertension (77% of medical conditions). Neonatal complications occurred in 183 infants (23%). The corrected perinatal death rate was 2.5 per 1000. Prematurity, IUGR and dysmaturity/postmaturity accounted for nearly half of the complications. Hyperbilirubinemia occurred in 7% of the cases. Among women without any maternal complications during pregnancy, the frequency rate of neonatal complications was 19%, compared with 23% among the entire group of 790 women. Our results suggest that the absence of maternal complications does not protect the infant from a neonatal complication. Further refinement is needed to identify markers of obstetric, medical and neonatal complications in pregnancies with no risk factors.

Effects of maternal oral salbutamol therapy on neonatal endocrine status at birth

Cord blood concentrations of insulin, growth hormone (GH), triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) from 20 patients treated with oral salbutamol were compared with those of 18 matched patients who had not received any betamimetic agents. No significant difference was found in circulating insulin, T3, T4, and TSH between both groups. However, GH levels were significantly higher in the treated group (36.5 +/- 17.4 ng/mL) than in the control group (17.4 +/- 6.6 ng/mL; P less than .001). The unexpected increase in GH levels in the treated group could reflect either fluctuating fetal blood glucose in response to episodic betamimetic administration or direct fetal pituitary production through adrenergic stimulation.

A prospective study of blood pressure in pregnancy: prediction of preeclampsia

A prospective study of blood pressure recording was conducted in 1000 patients, at each antenatal visit, with the use of an automatic random-zero sphygmomanometer. In 46 patients, among 808 primigravid women, who developed preeclampsia, the diastolic and mean blood pressures were significantly elevated compared to values at the first antenatal visit (p less than 0.01, 9 to 12 weeks). This difference was sustained throughout pregnancy until delivery by at least 10 mm Hg as compared to pressures in the normotensive group. Sensitivity for predicting preeclampsia early in pregnancy with an elevated blood pressure measurement (130 to 135/80 to 85 mm Hg) ranged from 16% to 57% while specificity ranged from 75% to 98%. The results substantiate an early vasospasm (9 to 12 weeks) in those women destined to develop preeclampsia.

The concentrations of urinary prostaglandins E and plasma prostaglandins F2 alpha and E during induction of ovulation with human gonadotropins

Plasma prostaglandins F2 alpha and E (PGF2 alpha, PGE) and urinary PGE were measured in 10 women treated with human gonadotropins (HMG) and subsequently with human chorionic gonadotropins (HCG). Five women became pregnant (6 pregnancies). There was no correlation between concentrations of plasma PGF2 alpha or PGE and plasma estradiol or progesterone. Urinary PGE concentrations showed a positive correlation with estradiol before HCG and a negative correlation with progesterone after HCG, only in women who subsequently became pregnant. Higher urinary PGE concentrations before HCG suggest that either HMG or rising estradiol levels stimulate PGE renal production. The significant negative correlation between urinary PGE and progesterone concentrations, after HCG, in those patients who became pregnant suggests that ovarian production of progesterone may decrease renal production of PGE.