Delayed normalization of uterine artery Doppler waveforms is not a benign phenomenon

Effects of late gestational nutrient restriction on uterine artery blood flow, placental size, and cotyledonary mRNA expression in primiparous beef females

Fall-calving primiparous beef females [body weight (BW): 451 ± 28 (SD) kg; body condition score (BCS): 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 13) or 70% (nutrient restricted; NR; n = 13) of metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to parturition. Doppler ultrasonography of both uterine arteries was conducted pre-treatment and every 21 d from days 181 to 265 of gestation. Expelled placentas were collected, and ipsilateral cotyledonary tissue was sampled to assess relative messenger ribonucleic acid (mRNA) expression. Placentas were separated into ipsilateral and contralateral sides, dissected (cotyledonary vs. intercotyledonary), and dried. Data were analyzed with nutritional plane, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Uterine blood flow included day and nutritional plane × day as repeated measures. We previously reported that post-calving, NR dams weighed 64 kg less and were 2.0 BCS lower than CON, but calf birth weight was not affected. Maternal heart rate was less (P < 0.001) for NR dams than CON after nutritional planes began. Nutritional plane did not affect (P ≥ 0.20) uterine artery hemodynamics, but all variables were affected (P ≤ 0.04) by day. Contralateral cotyledonary and placental weight were less (P ≤ 0.04) and contralateral intercotyledonary weight and number of cotyledons tended to be less (P ≤ 0.10) for NR dams than CON, but ipsilateral and whole placental weights were not affected (P ≥ 0.13). Ipsilateral placental weight as a percentage of total placental weight was greater (P = 0.03) for NR dams than CON. Whole placental cotyledonary: intercotyledonary weight was less (P = 0.01) for NR dams than CON. Placental efficiency was not affected (P = 0.89) by nutritional plane. Cotyledonary relative mRNA expression of GLUT3 and SNAT2 was greater (P ≤ 0.05) and relative expression of GLUT1, GLUT4, and NOS3 tended to be greater (P ≤ 0.07) for NR dams than CON. Nutritional plane did not affect (P ≥ 0.13) relative mRNA expression of GLUT5, 4F2hc, CAT1, LAT1, LAT2, VEGFA, FLT1, KDR, GUCY1B3, and PAG2. Despite less contralateral placental growth, beef heifers experiencing late gestational nutrient restriction maintained uterine artery blood flow and total placental mass and had 4 nutrient transporters and 1 angiogenic factor upregulated in cotyledons, all of which likely contributed to conserving fetal growth.

A Comparison of Changes in the Mean Arterial Blood Pressure and Mean Uterine Artery Pulsatility Index from 11-14 to 19-24 + 6 Gestation Weeks in Low-Risk and High-Risk Asian Indian Pregnant Women

Aim  The aim of this study was to determine the changes in the mean arterial blood pressure (MAP) and mean uterine artery (UtA) pulsatility index (PI) from 11-14 to 19-24 + 6 gestation weeks in Asian Indian pregnant women. Methods  Clinical and demographic details, MAP, and mean UtA PI measures were ascertained for pregnant women at 11 to 14 gestation weeks and 19-24 + 6 gestation weeks. Women were categorized as a high-or-low risk for preterm preeclampsia using the Fetal Medicine Foundation algorithm and 1 in 150 cutoff. High-risk pregnant women were recommended low-dose aspirin 150 mg daily at bedtime. Changes in MAP and mean UtA PI were compared for gestational age intervals and high-and-low risk women using nonparametric tests. Results  The study analyzed the results of 1,163 pregnant women. Both MAP (mean difference: 5.14, p  < 0.001) and mean UtA PI (mean difference: 0.14, p  < 0.001) remained significantly higher at the second-trimester assessment in high-risk pregnant women compared to low-risk pregnant women. Seventy-seven (35.16%) of the 219 pregnant women with abnormal mean UtA PI in the first trimester had an abnormal mean UtA PI in the second-trimester assessment. One hundred (10.59%) of the 944 pregnant women with normal mean UtA PI in the first trimester had an abnormal mean UtA PI in the 19-24 + 6 weeks assessment. Seventy-seven pregnant women (6.62% of 1,163 women, 95% confidence interval: 5.33, 8.20) had an abnormal mean UtA PI at both gestation age intervals. High-risk pregnant women taking low-dose aspirin daily showed a larger reduction in mean UtA PI compared to high-risk pregnant women that did not report the use of low-dose aspirin (0.89 vs. 0.62, p <0.001) Conclusion  MAP and mean UtA PI decreased significantly from the first to the second trimester of pregnancy. Sequential assessment of the MAP and mean UtA PI in the first and second trimesters of pregnancy will be useful for fetal radiologists in India to identify a subgroup of women with abnormal mean UtA PI at both trimesters that may need more intense surveillance and follow-up till childbirth.

Antiplatelet agents for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents, such as aspirin and dipyridamole, when given to women at risk of developing pre-eclampsia.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (30 March 2018), and reference lists of retrieved studies. We updated the search in September 2019 and added the results to the awaiting classification section of the review.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Studies only published in abstract format were eligible for inclusion if sufficient information was available. We would have included cluster-randomised trials in the analyses along with individually-randomised trials, if any had been identified in our search strategy. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were administration of an antiplatelet agent (such as low-dose aspirin or dipyridamole), comparisons were either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trials for inclusion and extracted data independently. For binary outcomes, we calculated risk ratio (RR) and its 95% confidence interval (CI), on an intention-to-treat basis. For this update we incorporated individual participant data (IPD) from trials with this available, alongside aggregate data (AD) from trials where it was not, in order to enable reliable subgroup analyses and inclusion of two key new outcomes. We assessed risk of bias for included studies and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

Seventy-seven trials (40,249 women, and their babies) were included, although three trials (relating to 233 women) did not contribute data to the meta-analysis. Nine of the trials contributing data were large (> 1000 women recruited), accounting for 80% of women recruited. Although the trials took place in a wide range of countries, all of the nine large trials involved only women in high-income and/or upper middle-income countries. IPD were available for 36 trials (34,514 women), including all but one of the large trials. Low-dose aspirin alone was the intervention in all the large trials, and most trials overall. Dose in the large trials was 50 mg (1 trial, 1106 women), 60 mg (5 trials, 22,322 women), 75mg (1 trial, 3697 women) 100 mg (1 trial, 3294 women) and 150 mg (1 trial, 1776 women). Most studies were either low risk of bias or unclear risk of bias; and the large trials were all low risk of bas. Antiplatelet agents versus placebo/no treatment The use of antiplatelet agents reduced the risk of proteinuric pre-eclampsia by 18% (36,716 women, 60 trials, RR 0.82, 95% CI 0.77 to 0.88; high-quality evidence), number needed to treat for one women to benefit (NNTB) 61 (95% CI 45 to 92). There was a small (9%) reduction in the RR for preterm birth <37 weeks (35,212 women, 47 trials; RR 0.91, 95% CI 0.87 to 0.95, high-quality evidence), NNTB 61 (95% CI 42 to 114), and a 14% reduction infetal deaths, neonatal deaths or death before hospital discharge (35,391 babies, 52 trials; RR 0.85, 95% CI 0.76 to 0.95; high-quality evidence), NNTB 197 (95% CI 115 to 681). Antiplatelet agents slightly reduced the risk of small-for-gestational age babies (35,761 babies, 50 trials; RR 0.84, 95% CI 0.76 to 0.92; high-quality evidence), NNTB 146 (95% CI 90 to 386), and pregnancies with serious adverse outcome (a composite outcome including maternal death, baby death, pre-eclampsia, small-for-gestational age, and preterm birth) (RR 0.90, 95% CI 0.85 to 0.96; 17,382 women; 13 trials, high-quality evidence), NNTB 54 (95% CI 34 to 132). Antiplatelet agents probably slightly increase postpartum haemorrhage > 500 mL (23,769 women, 19 trials; RR 1.06, 95% CI 1.00 to 1.12; moderate-quality evidence due to clinical heterogeneity), and they probably marginally increase the risk of placental abruption, although for this outcome the evidence was downgraded due to a wide confidence interval including the possibility of no effect (30,775 women; 29 trials; RR 1.21, 95% CI 0.95 to 1.54; moderate-quality evidence). Data from two large trials which assessed children at aged 18 months (including results from over 5000 children), did not identify clear differences in development between the two groups.

AUTHORS' CONCLUSIONS

Administering low-dose aspirin to pregnant women led to small-to-moderate benefits, including reductions in pre-eclampsia (16 fewer per 1000 women treated), preterm birth (16 fewer per 1000 treated), the baby being born small-for-gestational age (seven fewer per 1000 treated) and fetal or neonatal death (five fewer per 1000 treated). Overall, administering antiplatelet agents to 1000 women led to 20 fewer pregnancies with serious adverse outcomes. The quality of evidence for all these outcomes was high. Aspirin probably slightly increased the risk of postpartum haemorrhage of more than 500 mL, however, the quality of evidence for this outcome was downgraded to moderate, due to concerns of clinical heterogeneity in measurements of blood loss. Antiplatelet agents probably marginally increase placental abruption, but the quality of the evidence was downgraded to moderate due to low event numbers and thus wide 95% CI. Overall, antiplatelet agents improved outcomes, and at these doses appear to be safe. Identifying women who are most likely to respond to low-dose aspirin would improve targeting of treatment. As almost all the women in this review were recruited to the trials after 12 weeks' gestation, it is unclear whether starting treatment before 12 weeks' would have additional benefits without any increase in adverse effects. While there was some indication that higher doses of aspirin would be more effective, further studies would be warranted to examine this.

Antenatal placental assessment in the prediction of adverse pregnancy outcome after reduced fetal movement

OBJECTIVE

To assess the value of in utero placental assessment in predicting adverse pregnancy outcome after reported reduced fetal movements (RFM).

METHOD

A non-interventional prospective cohort study of women (N = 300) with subjective RFM at ≥28 weeks' gestation in singleton non-anomalous pregnancies at a UK tertiary maternity hospital. Clinical, sonographic (fetal weight, placental size and maternal, fetal and placental arterial Doppler) and biochemical (maternal serum hCG, hPL, progesterone, PlGF and sFlt-1) assessment was conducted. Multiple logistic regression identified combinations of measurements (models) most predictive of adverse pregnancy outcome (perinatal mortality, birth weight <10th centile, five minute Apgar score <7, umbilical arterial pH <7.1 or base excess <-10, neonatal intensive care admission). Models were compared by test performance characteristics (ROC curve, sensitivity, specificity, positive/negative predictive value, positive/negative likelihood ratios) against baseline care (estimated fetal weight centile, amniotic fluid index and gestation at presentation).

RESULTS

61 (20.6%) pregnancies ended in adverse outcome. Models incorporating PlGF/sFlt-1 ratio and umbilical artery free loop Doppler impedance demonstrated modest improvement in ROC area for adverse outcome (baseline care 0.69 vs. proposed models 0.73-0.76, p<0.05). However, there was little improvement in other test characteristics (baseline vs. best proposed model: sensitivity 21.7% [95% confidence interval 13.1-33.6] vs. 35.8%% [24.4-49.3], specificity 96.6% [93.4-98.3] vs. 94.7% [90.7-97.0], PPV 61.9% [40.9-79.3] vs. 63.3% [45.5-78.1], NPV 82.8% [77.9-86.8] vs. 85.2% [80.0-89.2], positive LR 6.3 [2.8-14.6] vs. 6.7 [3.4-3.3], negative LR 0.81 [0.71-0.93] vs. 0.68 [0.55-0.83]) and wide confidence intervals. Negative post-test probability remained high (16.7% vs. 14.0%).

CONCLUSION

Antenatal placental assessment may improve identification of RFM pregnancies at highest risk of adverse pregnancy outcome but further work is required to understand and refine currently available outcome definitions and diagnostic techniques to improve clinical utility.

Do low-risk nulliparous women with abnormal uterine artery Doppler in the third trimester have poorer perinatal outcomes? A longitudinal prospective study on uterine artery Doppler in low-risk nulliparous women and correlation with pregnancy outcomes

OBJECTIVE

To evaluate uterine artery (UtA) Doppler over the course of pregnancy in low-risk nulliparous women and to analyze whether an abnormal uterine artery pulsatility index (UtA-PI) at a 32-34 week' scan implies poorer perinatal outcomes.

METHODS

An observational prospective study was carried out including 616 low-risk nulliparous women. Women with any of the following were excluded: fetal abnormalities, multiple pregnancy, and heparin, metformin or hypotensive treatment. Maternal characteristics, mean arterial pressure measurements and UtA Doppler findings were recorded longitudinally.

RESULTS

Complete pregnancy data were available for 489/616 women (79.3%). Of these, 385 women had a normal UtA-PI throughout pregnancy (Group 0), while 50 (10.1%) had an UtA-PI > 95th percentile in the first or the second trimester that normalized in the third trimester (Group 1), and 56 (11.4%) had an abnormal UtA-PI in the third trimester (Group 2). We found that the rate of pre-eclampsia (PE) was higher in Group 2 (7/56 versus 4/435, p = 0.003) as was the rate of intrauterine growth restriction (IUGR) (6/56 versus 14/435, p = 0.02).

CONCLUSIONS

Low-risk nulliparous women with abnormal UtA Doppler findings in the third trimester are at a higher risk of developing PE and having a baby with IUGR.

Uterine and umbilical artery Doppler at 28 weeks for predicting adverse pregnancy outcomes in women with abnormal uterine artery Doppler findings in the early second trimester

OBJECTIVE

The objective of this study was to determine the contribution of uterine (UtA) and umbilical arteries (UA) Doppler examination at 28 weeks to predict adverse pregnancy outcomes in women who had increased resistance in UtA in the early second trimester.

METHODS

Women with UtA mean pulsatility index (PI) above the 95th centile at 19-22 weeks of gestation were offered a growth scan including Doppler examination of UtA and UA at 28 weeks. Adverse pregnancy outcomes included small for gestational age (SGA), defined as birth weight below the tenth centile, preeclampsia (PE) and early-onset PE (PE before 34 weeks).

RESULTS

We studied 266 pregnant women with elevated PI in the UtAs in the second trimester and ultrasound reassessment at 28 weeks. UtA PI >95th centile at 28 weeks was associated with subsequent PE [odds ratio (OR): 10.0, 95% CI: 2.3-43.5], early-onset PE (OR: 57.7, 95% CI: 3.8-87.6) and SGA less than the tenth centile (OR: 5.5, 2.2-13.9). UA PI >95th centile at 28 weeks was not significantly associated with any adverse outcome.

CONCLUSIONS

In women with abnormal UtA Doppler in the early second trimester scan, persistence of elevated UtA PI, but not abnormal UA PI, is associated with adverse pregnancy outcomes including PE, early-onset PE and SGA. © 2014 John Wiley & Sons, Ltd.

Association between first trimester vaginal bleeding and uterine artery Doppler measured at second and third trimesters of pregnancy

OBJECTIVE

To evaluate the prevalence of first trimester vaginal bleeding among patients with abnormal second and third trimester uterine artery Doppler.

METHODS

A prospective study of patients with a uterine artery Doppler measurement between 27 and 42 weeks' gestation was undertaken. A comparison was made between two groups: patients with and without first trimester vaginal bleeding. Abnormal uterine artery Doppler was defined as PI >95th% or the presence of a diastolic notch.

RESULTS

Of the 277 patients that were included in the study, 65 (23%) had first trimester vaginal bleeding. No differences were noted in uterine artery Doppler waveforms among patients with and without first trimester vaginal bleeding. Among patients with first trimester vaginal bleeding, 9 (14%) had a bilateral uterine artery notch and 56 (86%) did not, compared with 51 (24%) and 161 (76%), in the control group, respectively. Patients with first trimester vaginal bleeding, and a bilateral uterine artery notch had significantly higher rates of small for gestational age neonates, low-Apgar scores (<7) at one minute and cesarean deliveries compared to patients with first trimester vaginal bleeding who did not have bilateral uterine artery notch.

CONCLUSION

First trimester vaginal bleeding was not associated with a higher incidence of abnormal uterine artery waveforms or with placental related conditions. However, adverse perinatal outcomes were found when first trimester vaginal bleeding was associated with second and third trimester bilateral uterine artery notchs.

Increased uterine artery pulsatility index at 34 weeks and outcome of pregnancy

OBJECTIVES

To evaluate pregnancy outcome in patients with increased uterine artery (UtA) pulsatility at 34 weeks' gestation as an isolated finding.

METHODS

Normotensive women attending at 34 weeks' gestation for fetal growth assessment were enrolled in the study if fetal growth was appropriate for age and mean UtA pulsatility index (PI) was persistently above the 95(th) centile for gestational age. Patients were excluded with any of the following conditions: multiple pregnancy, sonographic suspicion of fetal anomaly or fetal growth restriction, history of chronic maternal disease, hypertensive disorder or diabetes in the current pregnancy or one or more adverse events in their past obstetric history. The control group consisted of age- and body mass index-matched low-risk women attending at 34 weeks with normal uterine artery Doppler since the midtrimester.

RESULTS

Sixty-six normotensive patients with normal fetal growth and increased UtA-PI at 34 weeks were included in the study group. Women with abnormal Doppler findings compared with controls showed significantly lower gestational age at delivery (38.2 ± 1.6 vs. 38.9 ± 1.3 weeks, P = 0.006), birth weight (2942 ± 583 vs. 3404 ± 469 g, P < 0.001), birth-weight Z-score (-0.61 ± 1.07 vs. 0.19 ± 1.05, P < 0.001) and increased risk of a small-for-gestational-age (SGA) newborn (13/66 vs. 1/66, P < 0.001). The occurrence of late pre-eclampsia (3/66 vs. 0/66, P = 0.24), admission to the neonatal intensive care unit (6/66 vs. 4/66, P = 0.74), rate of induction of labor (16/66 vs. 14/66, P = 0.83) and rate of Cesarean section due to fetal distress (6/66 vs. 3/66, P = 0.49) were comparable between the two groups.

CONCLUSION

Increased UtA-PI as an isolated finding at 34 weeks' gestation is associated with an increased risk of delivering an SGA neonate.

Persistence of increased uterine artery resistance in the third trimester and pregnancy outcome

OBJECTIVE

To evaluate whether the persistence of abnormal findings in the third trimester following increased uterine artery (UtA) resistance in the second trimester is related to adverse pregnancy outcome.

METHODS

Low-risk nulliparous women with increased UtA mean pulsatility index (PI) at 20-22 weeks underwent repeat Doppler interrogation at 26-28 weeks and were divided into two groups: those with persistently abnormal Doppler and those with normalized UtA findings. Pregnancy outcome was noted for all patients and compared with that of 104 controls.

RESULTS

We examined 104 women with increased UtA resistance in the second trimester and in 62 (59.6%) cases the abnormal uteroplacental Doppler findings persisted to 26-28 weeks. Compared with controls and with patients with normalized Doppler at the third-trimester scan, patients with persistently abnormal Doppler results had a significantly higher risk of pre-eclampsia (10/62 vs. 1/104, P = 0.002 and 10/62 vs. 1/42, P = 0.047, respectively), small-for-gestational age (SGA) fetus (20/62 vs. 1/104, P < 0.001 and 20/62 vs. 4/42; P = 0.007, respectively) and admission of the infant to a neonatal intensive care unit (16/62 vs. 4/104; P < 0.001 and 16/62 vs. 1/42; P < 0.001, respectively). Compared with controls, cases with normalization had an increased risk of SGA (4/42 vs. 1/104, P = 0.03), but there were no significant differences for the other outcome measures.

CONCLUSIONS

In low-risk nulliparous women with increased UtA resistance in the second trimester, the persistence of abnormal Doppler findings at 26-28 weeks is associated with an increased risk of obstetric complications when compared with both controls and patients with third-trimester Doppler normalization.

The maternal plasma soluble vascular endothelial growth factor receptor-1 concentration is elevated in SGA and the magnitude of the increase relates to Doppler abnormalities in the maternal and fetal circulation

OBJECTIVES

The soluble form of vascular endothelial growth factor receptor-1 (sVEGFR-1), an antagonist to vascular endothelial growth factor and placental growth factor, has been implicated in the pathophysiology of preeclampsia. Preeclampsia and pregnancy complicated with small for gestational age (SGA) fetuses share some pathophysiologic derangements, such as failure of physiologic transformation of the spiral arteries, endothelial cell dysfunction, and leukocyte activation. The objectives of this study were to: (1) determine whether plasma concentrations of sVEGFR-1 in mothers with SGA fetuses without preeclampsia at the time of diagnosis are different from those in patients with preeclampsia or normal pregnant women, and (2) examine the relationship between plasma concentrations of sVEGFR-1 and Doppler velocimetry in uterine and umbilical arteries in patients with preeclampsia and those with SGA.

STUDY DESIGN

A cross-sectional study was conducted to determine the concentrations of the soluble form of VEGFR-1 in plasma obtained from normal pregnant women (n = 135), women with SGA fetuses (n = 53), and patients with preeclampsia (n = 112). Patients with SGA fetuses and those with preeclampsia were sub-classified according to the results of uterine and umbilical artery Doppler velocimetry examinations. Plasma concentrations of sVEGFR-1 were determined by an ELISA. Since these concentrations change with gestational age, differences among various subgroups were statistically estimated with the delta value, defined as the difference between the observed and expected plasma sVEGFR-1 concentration. The expected values were derived from regression analysis of plasma sVEGFR-1 concentrations in normal pregnancy. Regression analysis and univariate and multivariate analysis were employed.

RESULTS

(1) Mothers with SGA fetuses had a mean plasma concentration of sVEGFR-1 higher than normal pregnant women (p < 0.001), but lower than patients with preeclampsia (p < 0.001). (2) Among patients with SGA fetuses, only those with abnormal uterine artery Doppler velocimetry had a mean plasma sVEGFR-1 concentration significantly higher than normal pregnant women (p < 0.001). (3) Among mothers with SGA fetuses in whom Doppler velocimetry was performed (n = 41), those with abnormalities in both the uterine and umbilical artery velocimetry had the highest mean delta of sVEGFR-1 plasma concentration (mean +/- standard deviation (SD): 0.69 +/- 0.29). Conversely, patients who had normal Doppler velocimetry in both uterine and umbilical arteries had the lowest mean delta (mean +/- SD: 0.09 +/- 0.29) of sVEGFR-1 plasma concentrations (ANOVA; p < 0.001). (4) Among patients with preeclampsia in whom Doppler velocimetry was performed (n = 69), those with abnormalities in both the uterine and umbilical artery velocimetry had the highest mean delta sVEGFR-1 plasma concentration (mean +/- SD: 1.01 +/- 0.22) among all groups classified (ANOVA; p < 0.001). (5) Among patients with SGA and those with preeclampsia, there was a relationship (Chi-square for trend p < 0.001 for both) between the severity of Doppler velocimetry abnormalities and the proportion of patients who had high delta sVEGFR-1 plasma concentrations (defined as a concentration two standard deviations (2SD) above the mean delta of normal pregnant women). (6) Multiple regression analysis suggested that the diagnostic category (e.g., SGA or preeclampsia), Doppler abnormalities, and gestational age at blood sampling were associated with an increase in plasma sVEGFR-1 concentrations (p < 0.001).

CONCLUSIONS

These observations provide support for the participation of the soluble receptor of vascular endothelial growth factor in the pathophysiology of SGA with abnormal uterine artery Doppler velocimetry and preeclampsia. An excess of sVEGFR-1 is released into the maternal circulation of patients with preeclampsia and those with SGA fetuses, as abnormalities of impedance to blood flow involve uterine and umbilical circulation.

Doppler examination of uteroplacental circulation in early pregnancy: can it predict adverse outcome?

PURPOSE

To determine whether spectral Doppler measurements obtained from bilateral uterine, arcuate, radial, and spiral arteries in early gestation correlate with adverse pregnancy outcome.

METHODS

One hundred five pregnant women underwent transvaginal Doppler sonographic examination of uteroplacental circulation at 6-12 weeks' gestation. Resistance index (RI) and pulsatility index (PI) of bilateral uterine, arcuate, radial, and spiral arteries were measured. Diameters of gestational sac (GS) and yolk sac, crown-rump length (CRL), GS-CRL difference, and GS/CRL ratio were also recorded. Correlation was made with pregnancy outcome.

RESULTS

Sixteen women developed adverse pregnancy outcome. In these women, right uterine artery PI and RI were significantly higher than in women with normal obstetrical outcome. Spiral artery PI and RI values were also higher, but the difference was not statistically significant. GS-CRL difference, GS/CRL ratio, and yolk sac diameters were significantly lower in this group.

CONCLUSION

Transvaginal Doppler examination can detect hemodynamic changes in uteroplacental circulation associated with subsequent adverse pregnancy outcome.

Antiplatelet agents for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia is associated with deficient intravascular production of prostacyclin, a vasodilator, and excessive production of thromboxane, a vasoconstrictor and stimulant of platelet aggregation. These observations led to the hypotheses that antiplatelet agents, low-dose aspirin in particular, might prevent or delay development of pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of antiplatelet agents for women at risk of developing pre-eclampsia.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (July 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 1), EMBASE (1994 to November 2005) and handsearched congress proceedings of the International and European Societies for the Study of Hypertension in Pregnancy.

SELECTION CRITERIA

All randomised trials comparing antiplatelet agents with either placebo or no antiplatelet agent were included. Quasi-random studies were excluded. Participants were pregnant women at risk of developing pre-eclampsia. Interventions were any comparisons of an antiplatelet agent (such as low-dose aspirin or dipyridamole) with either placebo or no antiplatelet.

DATA COLLECTION AND ANALYSIS

Two authors assessed trials for inclusion and extracted data independently.

MAIN RESULTS

Fifty-nine trials (37,560 women) are included. There is a 17% reduction in the risk of pre-eclampsia associated with the use of antiplatelet agents ((46 trials, 32,891 women, relative risk (RR) 0.83, 95% confidence interval (CI) 0.77 to 0.89), number needed to treat (NNT) 72 (52, 119)). Although there is no statistical difference in RR based on maternal risk, there is a significant increase in the absolute risk reduction of pre-eclampsia for high risk (risk difference (RD) -5.2% (-7.5, -2.9), NNT 19 (13, 34)) compared with moderate risk women (RD -0.84 (-1.37, -0.3), NNT 119 (73, 333)). Antiplatelets were associated with an 8% reduction in the relative risk of preterm birth (29 trials, 31,151 women, RR 0.92, 95% CI 0.88 to 0.97); NNT 72 (52, 119)), a 14% reduction in fetal or neonatal deaths (40 trials, 33,098 women, RR 0.86, 95% CI 0.76 to 0.98); NNT 243 (131, 1,666) and a 10% reduction in small-for-gestational age babies (36 trials, 23,638 women, RR 0.90, 95% CI0.83 to 0.98). There were no statistically significant differences between treatment and control groups for any other outcomes.

AUTHORS' CONCLUSIONS

Antiplatelet agents, largely low-dose aspirin, have moderate benefits when used for prevention of pre-eclampsia and its consequences. Further information is required to assess which women are most likely to benefit, when treatment is best started, and at what dose.

Sequential changes in uterine artery blood flow pattern between the first and second trimesters of gestation in relation to pregnancy outcome

OBJECTIVE

To describe sequential changes in uterine artery waveform between the first and second trimesters of gestation and to analyze their association with the subsequent risk of hypertensive disorders and fetal growth restriction (IUGR).

METHODS

Sequential uterine artery Doppler recordings were obtained in a final cohort of 870 singleton pregnancies over two gestational age intervals: 11-14 weeks and 19-22 weeks. The left and right uterine arteries were examined by color and pulsed Doppler and the mean pulsatility index (PI) as well as the presence of a bilateral protodiastolic notch were recorded during both intervals. Pregnancies were followed for occurrence of hypertensive disorders and IUGR.

RESULTS

Mean uterine artery PI showed a significant linear decrease within each of the two intervals considered, while the prevalence of a bilateral notch showed decreasing values only throughout 11-14 weeks of gestation. Sixty-four (7.3%) pregnancies developed a hypertensive disorder and/or IUGR, including three (0.34%) cases of gestational hypertension, 24 cases of pre-eclampsia (2.75%) and 37 (4.25%) of IUGR. Compared with pregnancies with a normal outcome, complicated pregnancies showed a significantly higher prevalence of a bilateral notch and a higher mean PI in each of the two intervals studied. Compared with normal pregnancies, complicated pregnancies had a significantly higher persistence of a bilateral notch (30% vs. 8%), a higher proportion of women with an abnormal first-trimester uterine artery PI shifting to normal in the second trimester (14% vs. 4%) and a higher incidence of a normal first-trimester mean PI that shifted to abnormal in the second trimester (13% vs. 4%). Persistence of an abnormal mean PI from the first to the second trimester identified the group with the greatest risk for adverse perinatal outcome (OR, 10.7; 95% CI, 3.7-30.9). In addition, women in whom the uterine artery mean PI shifted from abnormal to normal between the two trimesters and women in whom the reverse shift occurred showed a similar intermediate risk (OR, 5; 95% CI, 2.1-10.6), comparable to that in women with persistence of a bilateral notch (OR, 5.6; 95% CI, 2.9-10.7).

CONCLUSIONS

The sequence of changes in uterine flow between the first and second trimesters correlates with the subsequent development of hypertensive disorders and IUGR. Women with a persistent abnormal mean PI represent the group with the greatest risk for adverse perinatal outcome.

Uterine artery Doppler screening for adverse pregnancy outcome

PURPOSE OF REVIEW

This article reviews publications in the area of uterine artery Doppler screening that were published during the past year.

RECENT FINDINGS

Studies have shown that assessment of a woman's level of risk for pre-eclampsia by uterine artery Doppler performs better than maternal history alone. Combination of maternal history and uterine artery Doppler findings leads to even more accurate assessment of risk, and allows calculation of patient-specific risk. Combining screening with uterine artery Doppler and maternal serum biochemical markers has been explored in some studies, but data remain limited and larger prospective longitudinal studies are needed to asses the effectiveness of these techniques. A number of promising markers for development of the disease have been identified, however, including pregnancy associated plasma protein-A, inhibin-A, activin-A and fibronectin, as well as placental growth factor, vascular endothelial growth factor and soluble fms-like tyrosine kinase 1.

SUMMARY

Uterine artery Doppler has proved useful in identifying women at high and low risk for developing complications of uteroplacental insufficiency and may aid in stratifying antenatal care. In addition, it can identify women in whom biochemical markers should be measured in order to develop screening tests and aid in evaluation of the pathophysiology of impaired placentation and pre-eclampsia. Whether pharmacological intervention in women identified to be at high risk for pre-eclampsia on the basis of Doppler is effective in reducing the incidence of the disease remains to be established.