Selecting a birth weight standard for an indigenous population in a LMIC: A prospective comparative study

OBJECTIVES

The aim of the present study was to compare birth weight (BW) distribution and proportion of BWs below or above specified percentiles in low-risk singleton pregnancies in healthy South African (SA) women of mixed ancestry with expected values according to four BW references and to determine the physiological factors affecting BW.

METHODS

This was an ancillary study of a prospective multinational cohort study, involving 7060 women recruited between August 2007 and January 2015 in two townships of Cape Town, characterized by low socioeconomic status, and high levels of drinking and smoking. Detailed information about maternal and pregnancy characteristics, including harmful exposures, was gathered prospectively, allowing us to select healthy women with uncomplicated pregnancies without any known harmful exposures. In this cohort we compared the median BW and the proportion of BWs P90, 95 and 97 according to four reference standards (INTERGROWTH-21st, customized according to the method described by Mickolajczyk, Fetal Medicine Foundation and revised Fenton reference) with expected values. Appropriate parametric and nonparametric tests were used, and sensitivity analysis was performed for infant sex, first trimester bookings and women of normal body mass index (BMI). Multiple regression was used to explore effects of confounders. Written consent and ethics approval was obtained.

RESULTS

The cohort included 739 infants. The INTERGROWTH-21st standard was closest for the actual BW-distribution and categories. Below-expected BW was associated with boys, younger, shorter, leaner women, lower parity and gravidity. Actual BW was significantly influenced by maternal weight, BMI, parity and gestational age.

CONCLUSION

Of the four references assessed in this study, the INTERGROWTH-21st standard was closest for the actual BW distribution. Maternal variables significantly influence BW.

Trisomy 21 screening with αlpha software and the Fetal Medicine Foundation algorithm

BACKGROUND

Screening for trisomy 21 provides pregnant women with accurate risk information. Different algorithms are used to screen for trisomy 21 in South Africa (SA). The Fetal Medicine Foundation (FMF) provides software to screen for trisomy 21 in the first trimester by ultrasound or a combination of ultrasound and biochemistry (combined screening), and requires regular and stringent quality control. With αlpha software, first trimester combined screening and screening with biochemistry alone in the first or second trimester are possible. The αlpha screening requires quality control of biochemical tests, but not of ultrasound measurements. Ideally, a screening test should have a high detection and a low screen positive rate. Despite the availability of these screening programmes, only a minority of infants with trisomy 21 are detected prenatally, raising questions about the effectiveness of screening.

OBJECTIVES

To determine the screen positive and detection rates of prenatal screening for trisomy 21 in the SA private healthcare system.

METHODS

Data from the three largest laboratories collected between 2010 and 2015 were linked with genetic tests to assess screen positive and detection rates. Biochemical screening alone with αlpha software (first or second trimester) and combined screening using either FMF or αlpha software were compared.

RESULTS

One-third of an estimated 675 000 pregnancies in private practice in the 6-year study period underwent screening. There were 687 cases of trisomy 21 in 225 021 pregnancies, with only 239 (35%) diagnosed prenatally. The screen positive rates were 11.8% for first trimester biochemistry, 7.6% for second trimester biochemistry, 7.3% for first trimester FMF software ultrasound alone, 3.7% for combined first trimester screening with FMF software, and 3.5% for combined first trimester screening with αlpha software. The detection rates for a 5% false positive rate were 63% for first trimester biochemistry, 69% for second trimester biochemistry, 95% for combined first trimester screening with FMF software and 80% for combined first trimester screening with αlpha software. Detection and confirmation rates were highest with FMF software.

CONCLUSION

Screening with FMF software has a similar screen positive rate and better detection rate than screening with αlpha software. The low prenatal detection rate of trisomy 21 is mainly due to a low prevalence of screening. More research is needed in the SA setting to explore why screening and confirmatory testing after high-risk results are not performed in many pregnancies.

Impact of fetal growth restriction on pregnancy outcome in women undergoing expectant management for preterm pre-eclampsia

OBJECTIVES

To assess whether coexisting fetal growth restriction (FGR) influences pregnancy latency among women with preterm pre-eclampsia undergoing expectant management. Secondary outcomes assessed were indication for delivery, mode of delivery and rate of serious adverse maternal and perinatal outcomes.

METHODS

We conducted a secondary analysis of the Pre-eclampsia Intervention (PIE) and the Pre-eclampsia Intervention 2 (PI2) trial data. These randomized controlled trials evaluated whether esomeprazole and metformin could prolong gestation of women diagnosed with pre-eclampsia between 26 and 32 weeks of gestation undergoing expectant management. Delivery indications were deteriorating maternal or fetal status, or reaching 34 weeks' gestation. FGR (defined by Delphi consensus) at the time of pre-eclampsia diagnosis was examined as a predictor of outcome. Only placebo data from PI2 were included, as the trial showed that metformin use was associated with prolonged gestation. All outcome data were collected prospectively from diagnosis of pre-eclampsia to 6 weeks after the expected due date.

RESULTS

Of the 202 women included, 92 (45.5%) had FGR at the time of pre-eclampsia diagnosis. Median pregnancy latency was 6.8 days in the FGR group and 15.3 days in the control group (difference 8.5 days; adjusted 0.49-fold change (95% CI, 0.33-0.74); P < 0.001). FGR pregnancies were less likely to reach 34 weeks' gestation (12.0% vs 30.9%; adjusted relative risk (aRR), 0.44 (95% CI, 0.23-0.83)) and more likely to be delivered for suspected fetal compromise (64.1% vs 36.4%; aRR, 1.84 (95% CI, 1.36-2.47)). More women with FGR underwent a prelabor emergency Cesarean section (66.3% vs 43.6%; aRR, 1.56 (95% CI, 1.20-2.03)) and were less likely to have a successful induction of labor (4.3% vs 14.5%; aRR, 0.32 (95% CI, 0.10-1.00)), compared to those without FGR. The rate of maternal complications did not differ significantly between the two groups. FGR was associated with a higher rate of infant death (14.1% vs 4.5%; aRR, 3.26 (95% CI, 1.08-9.81)) and need for intubation and mechanical ventilation (15.2% vs 5.5%; aRR, 2.97 (95% CI, 1.11-7.90)).

CONCLUSION

FGR is commonly present in women with early preterm pre-eclampsia and outcome is poorer. FGR is associated with shorter pregnancy latency, more emergency Cesarean deliveries, fewer successful inductions and increased rates of neonatal morbidity and mortality. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Association of Placental Histology with the Pulsatility Index of Fetal and Uteroplacental Vessels during Pregnancy and with Birthweight Z-Score

Aims

To compare macro- and microscopic features of the placenta with the pulsatility index (PI) of the uterine (UtA), umbilical (UA) and middle cerebral arteries at 20-24- and 34-38-weeks' gestation, and with birthweight z-scores (BWZS).

Methods

Recruitment for the Safe Passage Study, which investigated the association of alcohol and tobacco use with stillbirth and sudden infant death syndrome, occurred from August 2007 to January 2015 at community clinics in Cape Town, South Africa. The population represents a predominantly homogenous population of pregnant women from a low socioeconomic residential area. This study is a further analysis of the data of the Safe Passage Study. It consists of 1205 singleton pregnancies for which placental histology was available, of whom 1035 had a known BWZS and 1022 and 979 had fetoplacental Doppler examinations performed at Tygerberg Academic Hospital at 20-24 and 34-38 weeks respectively. Features of the placenta were assessed according to international norms.

Results

Significantly higher ORs for the presence of individual and combined features of maternal vascular malperfusion (MVM) were found with lower BWZS and higher UtA PI values, more consistently than with higher UA PI values. Strongest associations were for a small placenta for gestational age (UtA OR 4.86 at 20-24 and 5.92 at 34-38 weeks; UA OR 5.33 at 20-24 and 27.01 at 34-38 weeks; low BWZS OR 0.31), for accelerated maturation (UtA OR 11.68 at 20-24 weeks and 18.46 at 34-38 weeks; low BWZS 0.61), for macroscopic infarction (UtA OR 6.08 at 20-24 weeks; UA OR 17.02 at 34-38 weeks; low BWZS OR 0.62) and for microscopic infarction (UtA OR 6.84 at 20-24 and 10.9 at 34-38 weeks; low BWZS OR 0.62).

Conclusion

There is considerable variability in the associations between individual features of MVM and increased UtA or UA PI and low BWZS. Although all MVM features currently carry equal weight in defining the condition of MVM, our data suggest that some should carry more weight than others. Macroscopic examination of the placenta may be helpful in identifying placental insufficiency as a small placenta for gestational age and macroscopic infarction were the features most strongly associated with outcomes.

Reference standards for facial measurements in early third trimester South African fetuses, and the effect of maternal and fetal characteristics

Fetal alcohol spectrum disorder (FASD) is a major problem worldwide and dysmorphic facial features may be a prenatal biomarker for FASD. Deviations from normal facial development cannot be explored before establishing the normal variation in a specific population, since ethnic differences may exist.Objectives: Main objective: to establish reference standards for 23 facial measurements on 3D ultrasound volumes obtained between days 196 and 224 of gestation in healthy unexposed South African fetuses from an area with historically high alcohol consumption prevalence and a population group with no existing normative values. Secondary objective: to assess the confounding effect of maternal and fetal characteristics.Design: This study involves 97 women (including 43 smokers) who had been enrolled in the Safe Passage Study (SPS), a large prospective multinational cohort study assessing the effects of prenatal alcohol exposure. They had adequate 3 D ultrasound volumes of the fetal face acquired at 28⁺⁰-31⁺⁶weeks in singleton pregnancies without comorbidities, congenital abnormalities or exposure to alcohol, marijuana, or methamphetamines from 4 weeks before conception.Participants, materials, setting, methods: The participants were recruited from two residential areas of low socioeconomic status in Cape Town. Meticulous information was collected on maternal and pregnancy characteristics, including alcohol use at different time points. Gestational age (GA) was based on ultrasound biometry before 24 weeks, and 3D ultrasound volumes were acquired trans-abdominally from a sagittal and axial plane of the fetal face. Volumes were independently assessed offline by two observers and the image with the best landmark definition was used for 23 facial measurements, representing features previously described in children with FASD. The relation to the exact GA was assessed by regression analysis, the expected mean value and standard error of the estimate (SEE) was determined to transform all raw measurements into z-scores, and the effect of possible confounders on z-scores was assessed by ANOVA.Results: Ten variables changed significantly with advancing GA (extraocular diameter, anteroposterior, medio-lateral and supero-inferior ocular diameter, ocular volume, interlens distance, prenasal thickness, nasal bone length, nose length and nose protrusion) and thirteen did not (interocular distance; interocular: extraocular diameter ratio, prenasal thickness: nasal bone length ratio, pronasal-subnasal distance, subnasal-mouth distance, philtrum length, upper vermillion thickness, nose-philtrum angle, maxillary angle, facial height, facial protrusion, frontomaxillary facial angle and maxilla-nasion-mandible angle). Reference values (expected mean and SEE) for the 23 measurements were established for each day.The z-scores of all facial measurements were not independently affected by maternal age, parity, gravidity, smoking or body mass index, but infant sex and birthweight z-score significantly influenced several z-scores (infant sex for extraocular, medio-lateral, and supero-inferior ocular diameter, ocular volume, prenasal thickness and nose protrusion; birthweight z-score for extraocular diameter, interocular and interlens distance, nose protrusion and maxillary angle).Limitations: GA was not always confirmed by first trimester ultrasound and some measurements could not be obtained in all cases due to suboptimal image quality. The cohort included few heavy smokers so an effect of heavy or continued smoking cannot be ruled out, and the effect of ethnicity was not assessed.Conclusions: These are the first local reference standards for fetal facial measurements and, to our knowledge, the first reference standards for the supero-inferior ocular diameter, face protrusion, upper vermillion thickness, maxillary angle, and nose-philtrum angle. They were broadly in keeping with published references, with small discrepancies explained by minor differences in technique. Even in this narrow GA window, the distribution of many variables changed over time and normal variation was significantly influenced by fetal sex and birthweight z-score. The possible confounding effect of these factors needs to be considered when assessing the impact of harmful exposures like alcohol on facial development.

Decreased endothelial function and increased subclinical heart failure in women several years after pre-eclampsia

OBJECTIVES

Pre-eclampsia (PE) is associated with both postpartum endothelial dysfunction and asymptomatic structural heart alterations consistent with heart failure Stage B (HF-B). In this study, we assessed the relationship between endothelial function, measured by flow-mediated dilation (FMD), and HF-B in women with a history of PE.

METHODS

This was an observational study in which 67 formerly pre-eclamptic women (≥ 4 years postpartum) and 37 healthy parous controls were assessed ultrasonographically for cardiac function and geometry, as well as for endothelial function by means of brachial artery FMD. HF-B was diagnosed as left ventricular hypertrophy (left ventricular mass index (LVMi) > 95 g/m² ), concentric remodeling (relative wall thickness > 0.42 and LVMi ≤ 95 g/m² ), mild systolic dysfunction (left ventricular ejection fraction > 40% and < 55%) or asymptomatic valvular disease. Cardiovascular and metabolic syndrome variables were compared between women with history of PE and controls, as well as between those in the formerly pre-eclamptic group who had HF Stage A, HF-B or no HF. Logistic regression analysis was performed to assess the associations of FMD with PE, metabolic syndrome risk factors and obstetric parameters.

RESULTS

The prevalence of HF-B amongst formerly pre-eclamptic women was three-fold higher than that observed for controls (25% vs 8%, P < 0.05), while FMD was lower in formerly pre-eclamptic women compared with controls (6.12% vs 8.22%, P < 0.01); history of PE remained associated independently with lower FMD after adjusting for metabolic syndrome risk factors and obstetric parameters (β, -1.88; 95% CI, -3.59 to -0.18). However, HF-B did not relate to low FMD in formerly pre-eclamptic women.

CONCLUSIONS

Years after pregnancy, formerly pre- eclamptic women have lower FMD and have HF-B more often compared with healthy parous controls. Nonetheless, HF-B was not related to reduced FMD. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Effects of alcohol, cigarettes, methamphetamine and marijuana exposure during pregnancy on maternal serum alpha-fetoprotein levels at 20-24 weeks'gestation

OBJECTIVE

To examine the effects of cigarette, marihuana and methamphetamine smoking and consumption of alcohol during pregnancy on maternal serum alpha-fetoprotein (MSAFP) levels at 20-24 weeks.

STUDY DESIGN

In the Safe Passage Study (SPS) more than 12,000 pregnant women were prospectively followed up during pregnancy and until the infant was one year old to examine the effects of exposure to alcohol during pregnancy on stillbirth and sudden infant death syndrome. The present study is a cross-sectional secondary analysis of MSAFP analyses done at 20-24 weeks gestation in 1,679 SPS participants, recruited at the Bishop Lavis Community Health Centre, Cape Town, South Arica.

RESULTS

Low or moderate alcohol consumption with or without smoking, nor methamphetamine or marihuana use affected mean MSAFP levels. High MSAFP levels were associated with high alcohol consumption, young age, low body mass index (BMI) (<18 kg/m²) or small mid upper arm circumference (MUAC) (<230mm). High MSAFP levels were associated with stillbirth, preterm birth, abruption and a birth weight z-score of less than -1.

CONCLUSION

The study confirms the association between high MSAFP levels and adverse pregnancy outcomes but, although exposure to smoking or drinking is associated with adverse pregnancy outcomes including stillbirth, MSAFP levels were not affected by any of these exposures except for continued high consumption of alcohol. The observed association between higher MSAFP levels and maternal nutritional status (as demonstrated by the lower MUAC and BMI) could explain some of the correlations of poor socioeconomic conditions with higher stillbirth rates effect.

Cardiac remodeling in normotensive pregnancy and in pregnancy complicated by hypertension: systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis was to describe comprehensively the pattern of cardiac remodeling during normotensive human singleton pregnancy and to compare it with that of pregnancy complicated by hypertension.

METHODS

We performed a meta-analysis of the current literature on cardiac remodeling during normotensive and complicated pregnancies. Literature was retrieved from PubMed (NCBI) and EMBASE (Ovid) databases. Included studies needed to report a reference measurement (matched non-pregnant control group, prepregnancy or postpartum) and measurements made during predetermined gestational-age intervals. Mean differences between reference and pregnancy data were calculated using the random-effects model described by DerSimonian and Laird.

RESULTS

Forty-eight studies were included in the meta-analysis, with publication dates ranging from 1977 to 2016. During normotensive pregnancy, most geometric indices started to increase in the second trimester. Left ventricular mass (LVM) increased by 28.36 (95% CI, 19.73-37.00) g (24%), and relative wall thickness (RWT) increased by 0.03 (95% CI, 0.02-0.05) (10%) compared with those in the reference group. During hypertensive pregnancy, LVM and RWT increased more than during normotensive pregnancy (92 (95% CI, 75.46-108.54) g (95%) and 0.14 (95% CI, 0.09-0.19) (56%), respectively).

CONCLUSIONS

During normotensive pregnancy, most cardiac geometric indices change from the second trimester onwards. Both LVM and RWT increase, by 20% and 10%, respectively, consistent with concentric rather than eccentric remodeling. Cardiac adaptation in hypertensive pregnancy deviates from that in healthy pregnancy by a greater change in LVM (95% increase from reference) and RWT (56% increase from reference). Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

CON4EI: Evaluation of QSAR models for hazard identification and labelling of eye irritating chemicals

Assessment of ocular irritation is a regulatory requirement in safety evaluation of industrial and consumer products. Although a number of in vitro ocular irritation assays exist, none are capable of fully categorizing chemicals as stand-alone assays. Therefore, the CEFIC-LRI-AIMT6-VITO CON4EI (CONsortium for in vitro Eye Irritation testing strategy) project was developed to assess the reliability of eight in vitro test methods and computational models as well as establishing an optimal tiered-testing strategy. For three computational models (Toxtree, and Case Ultra EYE_DRAIZE and EYE_IRR) performance parameters were calculated. Coverage ranged from 15 to 58%. Coverage was 2 to 3.4 times higher for liquids than for solids. The lowest number of false positives (5%) was reached with EYE_IRR; this model however also gave a high number of false negatives (46%). The lowest number of false negatives (25%) was seen with Toxtree; for liquids Toxtree predicted the lowest number of false negatives (11%), for solids EYE_DRAIZE did (17%). It can be concluded that the training sets should be enlarged with high quality data. The tested models are not yet sufficiently powerful for stand-alone evaluations, but that they can surely become of value in an integrated weight-of-evidence approach in hazard assessment.

Maternal childhood trauma, postpartum depression, and infant outcomes: Avoidant affective processing as a potential mechanism

BACKGROUND

Women who have experienced childhood trauma may be at risk for postpartum depression, increasing the likelihood of negative outcomes among their children. Predictive pathways from maternal childhood trauma to child outcomes, as mediated by postpartum depression, require investigation.

METHODS

A longitudinal sample of South African women (N=150) was followed through pregnancy and postpartum. Measures included maternal trauma history reported during pregnancy; postpartum depression through six months; and maternal-infant bonding, infant development, and infant physical growth at one year. Structural equation models tested postpartum depression as a mediator between maternal experiences of childhood trauma and children's outcomes. A subset of women (N=33) also participated in a lab-based emotional Stroop paradigm, and their responses to fearful stimuli at six weeks were explored as a potential mechanism linking maternal childhood trauma, postpartum depression, and child outcomes.

RESULTS

Women with childhood trauma experienced greater depressive symptoms through six months postpartum, which then predicted negative child outcomes at one year. Mediating effects of postpartum depression were significant, and persisted for maternal-infant bonding and infant growth after controlling for covariates and antenatal distress. Maternal avoidance of fearful stimuli emerged as a potential affective mechanism.

LIMITATIONS

Limitations included modest sample size, self-report measures, and unmeasured potential confounders.

CONCLUSIONS

Findings suggest a mediating role of postpartum depression in the intergenerational transmission of negative outcomes. Perinatal interventions that address maternal trauma histories and depression, as well as underlying affective mechanisms, may help interrupt cycles of disadvantage, particularly in high-trauma settings such as South Africa.

Psychosocial predictors of fetoplacental blood flow during pregnancy

BACKGROUND

Although a number of studies have found significant associations between maternal psychological distress, anxiety and changes in fetoplacental blood flow, findings remain inconsistent. A recent pilot study by our group highlighted some of these inconsistencies. In the current study, we expanded this pilot analysis to include psychological distress, anxiety and a range of antenatal variables, with the aim of identifying predictors of fetoplacental blood flow.

METHODS

Healthy pregnant women (n=148) underwent Doppler flow studies on uterine, umbilical and fetal arteries; as well as assessments of distress, anxiety and other antenatal variables (e.g. perceived social support, resilience, nicotine and alcohol use) in each trimester.

RESULTS

Stepwise regression analyses found that state anxiety was associated with lower mid-cerebral artery pulsatility index at trimester 3.

LIMITATIONS

Subjects were recruited from selected midwife obstetric units in the same health district, so the generalizability of our results may be limited. While most subjects received Doppler assessment at trimesters 2 and 3, only approximately half of our sample was assessed at trimester 1.

CONCLUSION

The finding that anxiety is associated with increased blood flow to the fetal brain during trimester 3 of pregnancy, coincide with previous work. The findings emphasize a growing appreciation of the potential importance of psychological well-being during pregnancy for infant development. However, as associations were small and variable, further research using multivariate models to determine the precise mechanisms underlying these associations would be warranted.

Congenital rubella with agenesis of the inferior cerebellar vermis and total anomalous pulmonary venous drainage

Congenital rubella infection has been associated with a number of abnormalities including cardiac, central nervous system and placental complications. We present a case with multiple fetal abnormalities detected on prenatal ultrasound, and confirmed postnatally, that included a single umbilical artery, severe tricuspid regurgitation, micrognathia and agenesis of the inferior cerebellar vermis. Postnatal echocardiography additionally revealed unobstructed total anomalous pulmonary venous drainage (TAPVD) into the coronary sinus. Placental examination showed signs of placentitis, and polymerase chain reaction on neonatal serum was positive for rubella. Following a multidisciplinary team review, it was decided to provide only supportive care, and the infant died at 6 months of age owing to a respiratory tract infection. To our knowledge, TAPVD and agenesis of the inferior cerebellar vermis have not been reported previously in association with congenital rubella infection. This case illustrates how congenital infection may present in atypical ways and stresses the importance of considering congenital infection in the differential diagnosis of fetal anomalies when multiple features are present.

Feasibility of non-contrast-enhanced magnetic resonance angiography for imaging upper extremity vasculature prior to vascular access creation

OBJECTIVES

Preoperative mapping of arterial and venous anatomy helps to prevent postoperative complications after vascular access creation. The use of gadolinium in contrast-enhanced (CE) magnetic resonance angiography (MRA) has been linked to nephrogenic systemic fibrosis in patients with end-stage renal disease (ESRD). The purpose of this study was to evaluate non-contrast-enhanced (NCE) MRA for assessment of upper extremity and central vasculature and to compare it with CE-MRA.

METHODS

NCE and CE-MRA images were acquired in 10 healthy volunteers and 15 patients with ESRD. In each data set, two observers analysed 11 arterial and 16 venous segments with regard to image quality (0-4), presence of artefacts (0-2) and vessel-to-background ratio.

RESULTS

More arterial segments were depicted using CE-MRA compared to NCE-MRA (99% vs. 96%, p = 0.001) with mean image quality of 3.80 vs. 2.68, (p < 0.001) and mean vessel-to-background ratio of 6.47 vs. 4.14 (p < 0.001). Ninety-one percent of the venous segments were portrayed using NCE-MRA vs. 80% using CE-MRA (p < 0.001). Mean image quality and vessel-to-background ratio were 2.41 vs. 2.21 (p = 0.140) and 5.13 vs. 3.88 (p < 0.001), respectively.

CONCLUSIONS

Although arterial image quality and vessel-to-background ratios were lower, NCE-MRA is considered a feasible alternative to CE-MRA in patients with ESRD who need imaging of the upper extremity and central vasculature prior to dialysis access creation.

Which is the most accurate formula to estimate fetal weight in women with severe preterm preeclampsia?

OBJECTIVE

To identify the most accurate formula to estimate fetal weight (EFW) from ultrasound parameters in severe preterm preeclampsia.

METHODS

In a prospective study, serial ultrasound assessments were performed in 123 women with severe preterm preeclampsia. The EFW, calculated for 111 live born, normal, singleton fetuses within 7 days of delivery using 38 published formulae, was compared to the actual birth weight (ABW). Accuracy was assessed by correlations, mean (absolute and signed) (%) errors, % correct predictions within 5-20% of ABW and limits of agreement.

RESULTS

Accuracy was highly variable. Most formulae systematically overestimated ABW. Five Hadlock formulae utilizing three or four variables and Woo 3 formula had the highest accuracy and did not differ significantly (mean absolute % errors 6.8-7.2%, SDs 5.3-5.8%, > 75% of estimations within 10% of ABW and 95% limits of agreement between -18/20% and +14/15%). They were not negatively affected by clinical variables but had some inconsistency in bias over the ABW range. All other formulae, including those targeted for small, preterm or growth restricted fetuses, were inferior and/or affected by multiple clinical variables.

CONCLUSION

In this GA window, Hadlock formulae using three or four variables or Woo 3 formula can be recommended.

Association between antenatal distress and uterine artery pulsatility index

Although studies have found associations between maternal distress/anxiety and alterations in blood flow, data across different trimesters are inconsistent. We, therefore, sought to determine the association between measures of distress and uterine blood flow in all three trimesters. Healthy women with low-risk singleton pregnancies were recruited from antenatal clinics. Women were assessed at 13-14 weeks (T1), 21-22 weeks (T2), and 32-33 weeks (T3) of gestation with measures of distress and anxiety (the K10, Perceived Stress Scale, and the State Subscale of the Spielberger State-Trait Anxiety Inventory [STAI]) and with uterine Doppler flow velocity studies. The Trait Subscale of the STAI was done either at T1 or T2. Thirty women were seen at T1, 79 women were seen at T2, and 59 women were seen at T3. No significant correlations were found between measures of distress and anxiety and umbilical artery pulsatility index (PI) or middle cerebral artery PI at any time-point. Small positive correlations between trait anxiety and uterine artery PI were found, but these were not significant after adjustment for alcohol and nicotine use (any use as well as problem drinking/nicotine dependence). At T3 but not T1 or T2, women scoring above 20 on the K10 (a standardized cutoff for the presence of axis I psychiatric disorders) had higher uterine artery PI than those scoring below 20.This was significant after adjusting for alcohol and nicotine use, as well as when nicotine dependence was considered. This work highlights the complexities of the relationship between increased measures of distress and anxiety and changes in the placental circulation. Further work in this area is needed to explore the underlying mechanisms which account for this relationship and to delineate fully the extent to which the relationship is determined by the presence of psychiatric and substance use disorders.

Centile charts of cervical length between 18 and 32 weeks of gestation

OBJECTIVE

To establish a centile chart of cervical length between 18 and 32 weeks of gestation in a low-risk population of women.

METHODS

A prospective longitudinal cohort study of women with a low risk, singleton pregnancy using public healthcare facilities in Cape Town, South Africa. Transvaginal measurement of cervical length was performed between 16 and 32 weeks of gestation and used to construct centile charts. The distribution of cervical length was determined for gestational ages and was used to establish estimates of longitudinal percentiles. Centile charts were constructed for nulliparous and multiparous women together and separately.

RESULTS

Centile estimation was based on data from 344 women. Percentiles showed progressive cervical shortening with increasing gestational age. Averaged over the entire follow-up period, mean cervical length was 1.5 mm shorter in nulliparous women compared with multiparous women (95% CI, 0.4-2.6).

CONCLUSIONS

Establishment of longitudinal reference values of cervical length in a low-risk population will contribute toward a better understanding of cervical length in women at risk for preterm labor.

Severe early onset pre-eclampsia: prognostic value of ultrasound and Doppler assessment

OBJECTIVE

Assess the prognostic value of ultrasound and Doppler parameters in severe preterm pre-eclampsia.

STUDY DESIGN

Prospective cohort study in Cape Town, South Africa, involving 113 women with severe pre-eclampsia between 24 and 34 weeks of gestation and managed expectantly when suitable. Serial ultrasound and multivessel Doppler assessments were performed 2 to 3 times weekly. Observations included fetal weight estimation, growth pattern, amniotic fluid volume, appearance of the heart and bowel, pulsatility index of the uterine, umbilical and middle cerebral arteries and ductus venosus. Perinatal outcome (death or neurological compromise, n=12) and major morbidity (n=62) were related to findings at recruitment and on the last assessment preceding delivery.

RESULTS

In univariate analysis, fetal growth asymmetry and waveform analysis of all three fetal vessels significantly correlated with both end points. The initial fetal weight estimation with a cutoff weight of 1080 g had the highest sensitivity (83.3%) and negative predictive value (97.5%) for poor outcome (P<0.001) while the final ductus venosus pulsatility index had the highest specificity (92%) and positive predictive value (33%). The combination of a raised placentocerebral ratio and ductus venosus pulsatility index close to delivery had the highest (57.1%) positive predictive value. Logistic regression showed the best overall predictive model for poor outcome to be a combination of initial fetal weight estimation and final ductus venosus pulsatility index (overall accuracy 94.6%, RR 20.20 (7.36, 55.41)). The initial fetal weight estimation with a cutoff weight of 1283 g provided the best correct prediction of major morbidity (83.2% overall accuracy, sensitivity 79.0%, specificity 88.2%, positive and negative predictive values of 89.1 and 77.6% respectively). This was better than using the gestational age at recruitment or delivery, birth weight or any of the Doppler results. The prediction of morbidity was not improved by the addition of any other variable in logistic regression analysis.

CONCLUSION

For the short-term outcome measures assessed in this study, the estimated fetal weight at the time of diagnosis is the most important prognostic factor in severe pre-eclampsia with some additional value of ductus venosus assessment.

A case of hydatid cyst associated with postpartum maternal death

A young, apparently healthy woman from a rural area in South Africa presented in the third trimester of pregnancy with a symptomatic abdominal mass between the uterine fundus and liver. The etiology was established to be an echinococcus cyst of the liver and medical treatment was initiated. The fetal outcome was good but the mother died 3 days postpartum due to an unusual but devastating complication of the hydatid cyst.

Sonographic measurement of cervical length and fetal fibronectin testing in threatened preterm labor

OBJECTIVE

In women presenting with threatened preterm labor, both fetal fibronectin and sonographic measurement of cervical length have been shown to distinguish between true and false labor. The aim of this study was to determine whether the combination of both tests provides a better prediction than the individual tests alone.

METHODS

We examined 195 women with singleton pregnancies presenting at 24-36 (median 31) weeks of gestation with regular and painful uterine contractions, intact membranes and cervical dilatation of less than 3 cm. On admission to the hospital fetal fibronectin positivity in cervicovaginal secretions was determined and transvaginal sonographic measurement of cervical length was carried out. The results were not made available to the attending obstetrician. The primary outcome measure was delivery within 7 days of presentation.

RESULTS

Delivery within 7 days occurred in 51.4% (18 of 35) of those with cervical length below 15 mm and 0.6% (1 of 160) of those with cervical length of 15 mm or more, in 21.2% (18 of 85) of the fibronectin positive group and in 0.9% (1 of 110) of the fibronectin negative group. There was a significant association between cervical length and the incidence of fibronectin positivity (r = -0.921, P = 0.003). Logistic regression analysis demonstrated that the only significant contributor to the prediction of delivery within 7 days was cervical length, with no significant contribution from fibronectin positivity, ethnic origin, maternal age, gestational age, body mass index, parity, previous history of preterm delivery, cigarette smoking, or use of tocolytics.

CONCLUSIONS

In women with threatened preterm labor assessment of fetal fibronectin in cervicovaginal secretions does not improve the prediction of delivery within 7 days provided by the sonographic measurement of cervical length.

Effects of psychologic stress on fetal development and pregnancy outcome

Data from animal studies show that maternal stress is associated with disturbances in pregnancy outcomes and offspring development and behavior, possibly as a result of permanent structural and functional changes termed "early-life programming." There is growing interest in whether similar relationships are present in humans. Here we review recent significant findings from the literature on the impact of prenatal psychologic stressors on pregnancy outcome and offspring development, with a particular focus on the developing brain. Relevant papers were searched using PubMed, and reference lists from obtained articles were checked. In humans, prenatal stress is associated with pregnancy complications, developmental, cognitive, and behavioral disorders, and possible onset of psychopathology in later life. In contrast to the available research done in animals, virtually nothing is known about the effects of prenatal stress on morphologic fetal brain development, and the mechanisms underlying subsequent associated behavioral changes.

Sonographic measurement of cervical length in threatened preterm labor in singleton pregnancies with intact membranes

OBJECTIVES

To predict when delivery will occur, within 48 h and 7 days of presentation and before 35 weeks' gestation in women presenting with threatened preterm labor.

METHODS

Sonographic measurement of cervical length was carried out in 510 women with singleton pregnancies presenting with threatened preterm labor and intact membranes at 24 to 33 + 6 weeks of gestation. The measurement was not taken into account in the subsequent management of the pregnancies. The outcome measures were delivery within 48 h and 7 days of presentation and delivery before 35 weeks.

RESULTS

The median gestation at presentation was 30 + 1 (range, 24 to 33 + 6) weeks and the median cervical length was 25 (range, 1-51) mm. Delivery within 48 h of presentation occurred in 21 (4.1%) cases, delivery within 7 days occurred in 43 (8.4%) and delivery before 35 weeks occurred in 76 (14.9%). Logistic regression analysis demonstrated that the only significant independent predictor of delivery within 48 h was cervical length (odds ratio (OR), 0.73; 95% CI, 0.65-0.81) and for delivery within 7 days the independent predictors were cervical length (OR, 0.69; 95% CI, 0.63-0.76) and vaginal bleeding (OR, 19.42; 95% CI, 3.87-97.4). In the subgroup of women who did not deliver within 7 days of presentation, the incidence of delivery before 35 weeks was 7.1% (33 of 467) and the only significant independent predictor of such delivery was cervical length (OR, 0.92; 95% CI, 0.88-0.96, P < 0.0001). There was no significant independent contribution to any of the outcome measures from ethnic group, maternal age, gestational age, body mass index, parity, cigarette smoking or use of tocolytics.

CONCLUSIONS

In women with threatened preterm labor sonographic measurement of cervical length helps to distinguish between true and false labor and to predict early preterm delivery.

Sonographic cervical length in threatened preterm labor in a South African population

OBJECTIVE

In a previous study conducted in the UK we demonstrated that only 8% of women with threatened preterm labor deliver within 7 days. Furthermore, delivery within 7 days occurred in less than 1% of women presenting with a sonographically measured cervical length > or = 15 mm, compared to 37% in those with cervical length < 15 mm. In this study we investigate the potential value of cervical length in the prediction of outcome of threatened preterm labor in a South African population.

METHODS

We examined 63 women with singleton pregnancies presenting with regular and painful uterine contractions at 24-36 (mean, 31) weeks of gestation. Women in active labor, defined by the presence of cervical dilatation > or = 3 cm, and those with ruptured membranes were excluded. On admission to the hospital a transvaginal scan was performed to measure the cervical length. The subsequent management was determined by the attending obstetrician. The primary outcome was delivery within 7 days of presentation.

RESULTS

Delivery within 7 days of presentation occurred in 20/63 (32%) pregnancies, including 20 of the 30 (67%) cases with cervical length < 15 mm and none of the 33 cases with cervical length > or = 15 mm. Logistic regression analysis demonstrated that the only significant contributor in the prediction of delivery within 7 days was cervical length (odds ratio 0.67; 95% CI 0.54-0.85; P = 0.001) with no significant independent contribution from maternal age, gestational age, body mass index, parity, use of antibiotics, previous history of preterm delivery, cigarette smoking, contraction frequency or use of tocolytics.

CONCLUSION

In this South African population, which had a high incidence of delivery within 7 days of presentation with threatened preterm labor, sonographic measurement of cervical length is equally effective as in a lower-risk population in distinguishing between true and false labor.

Vitrectomy for epiretinal membranes: visual outcome and prognostic criteria

The treatment of choice for epiretinal membranes (ERM) causing marked retinal distortion and substantial visual impairment remains vitreoretinal surgery. The purpose of this study was to evaluate the results of surgery performed in our department and to investigate the prognostic value of different factors such as preoperative best-corrected visual acuity (BCVA), pre-existing cystoid macular edema (CME), intra-operative peeling of the internal limiting membrane (ILM), age and duration of symptoms. Eighty-eight consecutive eyes of 88 patients were operated on for ERM from July 1998 to June 2000. Both idiopathic and secondary cases were included. In all cases the ERM was successfully removed from the fovea. Mean BCVA after surgery increased from Snellen 0.2 (hand motion (HM) - 0.6) to Snellen 0.5 (HM - 1.0) (p<0.0001). Our results confirm the efficacy of surgical removal of the ERM in improving the visual acuity. Although not statistically significant, mean postoperative BCVA was slightly better in the group without pre-existing CME (p>0.05) and in the group where peeling of the ILM was performed (p>0.05). The data suggest that early surgery is likely to decrease the risk of developing irreversible macular damage (p<0.05). Because accelerated nuclear sclerosis with visual impairment is a common phenomenon after vitrectomy, one might consider performing a phaco-emulsification at the same time, especially in the elderly.

A community-based obstetric ultrasound service

OBJECTIVES

To investigate the impact of an ultrasound dating service on obstetric services.

METHODS

A prospective trial with 3009 unselected women presenting for antenatal care at two Midwife Obstetric Units in a socioeconomically deprived urban area, South Africa. In the study unit, student ultrasonographers provided a basic ultrasound service. In the control unit, obstetric ultrasound was only available for specific indications. The main outcome measures were number of antenatal visits and referrals for fetal surveillance.

RESULTS

The two cohorts were comparable except for the number of primigravidas but stratified analysis according to parity did not affect the results. Ultrasonography did not alter pregnancy outcome but reduced the number of perceived preterm labors/ruptured membranes (12.0 vs. 16.7%, P<0.003), post-term deliveries (8.1 vs. 10.8%, P<0.04) and referrals for fetal surveillance [15.9 vs. 29.6%, P<0.000, RR 0.79 (0.71-0.88)].

CONCLUSIONS

This community-based basic ultrasound service significantly reduced referrals to a regional center for fetal surveillance and delivery.

Megacystis at 10-14 weeks of gestation: chromosomal defects and outcome according to bladder length

AIMS

To examine the prevalence of chromosomal defects and outcome of fetuses with megacystis at 10-14 weeks of gestation.

METHODS

At the 10-14-week scan fetal megacystis was defined by a longitudinal bladder diameter of 7 mm or more. In 145 such fetuses the fetal karyotype and pregnancy outcome were examined in relation to the longitudinal diameter of the fetal bladder.

RESULTS

Chromosomal defects, mainly trisomies 13 and 18, were present in 30 cases. In the group with longitudinal bladder diameter of 7-15 mm the incidence of chromosomal defects was 23.6% (26/110), whereas in those with bladder diameter > 15 mm the incidence was 11.4% (4/35). The fetal nuchal translucency (NT) was above the 95th centile of the normal range for crown-rump length in a higher proportion of cases with abnormal rather than normal karyotype (76.7% compared to 31.3%; Chi-square P < 0.0001). The expected number of cases of trisomy 21, estimated on the basis of maternal age, gestational age and fetal NT, was 6.2 rather than the observed 2 and the corresponding numbers for trisomies 13 or 18 were 4.2 for expected and 24 for observed. In the chromosomally normal group with longitudinal bladder diameter of 7-15 mm follow-up scans demonstrated spontaneous resolution of the megacystis in 90% of the cases and enlargement of the megacystis and/or the development of echogenic kidneys in 10%. In contrast, none of the cases with bladder diameter > 15 mm demonstrated spontaneous resolution of the megacystis.

CONCLUSIONS

In fetal megacystis with longitudinal bladder diameter of 7-15 mm there is a risk of about 25% that the fetus will have a chromosomal defect but in the chromosomally normal group there is spontaneous resolution of the megacystis in about 90% of cases. If the bladder diameter is > 15 mm the risk of chromosomal defects is about 10% and in the chromosomally normal group the condition is invariably associated with progressive obstructive uropathy.

Hypophosphatasia associated with increased nuchal translucency: a report of two affected pregnancies

Perinatal hypophosphatasia is a lethal autosomal recessive skeletal abnormality with a birth prevalence of about 1 per 100 000. It is characterized by deficiency of the tissue-nonspecific isoenzyme of alkaline phosphatase causing abnormal bone mineralization. In the two affected fetuses from the same family ultrasound examination at 14 and 12 weeks, respectively, demonstrated increased nuchal translucency thickness, hypomineralization of the skull and spine, narrowing of the chest and shortening of the limbs.

Blackfan-Diamond anemia and dyserythropoietic anemia presenting with increased nuchal translucency at 12 weeks of gestation

Blackfan-Diamond anemia is a congenital hypoplastic anemia with a birth prevalence of about 1 in 200,000, usually presenting in the first few months of life and commonly associated with cardiac, urogenital and digital anomalies. Congenital dyserythropoietic anemias are a group of rare congenital anemias characterized by ineffective erythropoiesis. We report on two cases of congenital fetal anemia, one with Blackfan-Diamond anemia and one with dyserythropoietic anemia, presenting with increased nuchal translucency at 12 weeks of gestation.

Characterization of the normal cardiac myofiber field in goat measured with MR-diffusion tensor imaging

Cardiac myofiber orientation is a crucial determinant of the distribution of myocardial wall stress. Myofiber orientation is commonly quantified by helix and transverse angles. Accuracy of reported helix angles is limited. Reported transverse angle data are incomplete. We measured cardiac myofiber orientation postmortem in five healthy goat hearts using magnetic resonance-diffusion tensor imaging. A novel local wall-bound coordinate system was derived from the characteristics of the fiber field. The transmural course of the helix angle corresponded to data reported in literature. The mean midwall transverse angle ranged from -12 +/- 4 degrees near the apex to +9.0 +/- 4 degrees near the base of the left ventricle, which is in agreement with the course predicted by Rijcken et al. (18) using a uniform load hypothesis. The divergence of the myofiber field was computed, which is a measure for the extent to which wall stress is transmitted through the myofiber alone. It appeared to be <0.07 mm(-1) throughout the myocardial walls except for the fusion sites between the left and right ventricles and the insertion sites of the papillary muscles.

Congenital lymphedema presenting with increased nuchal translucency at 13 weeks of gestation

Congenital lymphedema is an autosomal dominant condition characterized by chronic tissue swelling caused by deficient lymphatic drainage due to hypoplastic/aplastic lymphatic vessels and usually affecting the lower limbs. The locus of the gene has been identified in the long arm of chromosome 15. We report one case of congenital lymphedema presenting with increased nuchal translucency at 13 weeks of gestation.

Congenital nephrotic syndrome presenting with increased nuchal translucency in the first trimester

Congenital nephrotic syndrome of the Finnish type (CNF) and diffuse mesangial sclerosis (DMS) are rare causes of renal failure in infants. We report two cases, one of each condition, presenting with increased nuchal translucency at the 11-14-week scan, and review the literature.

Impaired vascular reactivity in pregnant women with insulin-dependent diabetes mellitus

OBJECTIVE

The purpose of this study was to investigate the vascular function of pregnant women with insulin-dependent diabetes mellitus, using a noninvasive method.

STUDY DESIGN

This was a cross-sectional study that examined vascular function, which was assessed by flow-mediated dilatation of the brachial artery, in 37 pregnant women with insulin-dependent diabetes mellitus and in 37 healthy pregnant women at 20 weeks of gestation. The control of diabetes was also assessed by the measurement of glycosylated hemoglobin. Data were analyzed by 2-sided unpaired t test and multivariate regression analysis.

RESULTS

In the pregnant women with insulin-dependent diabetes mellitus, flow-mediated dilatation of the brachial artery was significantly lower than in healthy pregnant women (6.43% +/- 3.66% vs 9.43% +/- 3.69%, respectively; P =.0008). This difference was apparent even after an adjustment was made for blood vessel diameter, which was different between the 2 populations (P =.01). Flow-mediated dilatation in diabetic women was significantly correlated with the duration of diabetes (P =.01) but not with the levels of glycosylated hemoglobin.

CONCLUSION

Maternal insulin-dependent diabetes mellitus is associated with an impaired vasodilatory response to a blood flow stimulus. This vascular dysfunction is associated with the duration of the diabetes.

Natural inhibitors of neutrophil function in acute respiratory distress syndrome

OBJECTIVE

Neutrophils play a key role in the physiopathogenesis of acute lung injury in general and acute respiratory distress syndrome (ARDS) in particular. To identify the anti-inflammatory mediators with a protective effect on lung tissue damage in ARDS, we correlated the concentration of the Clara cell 16-kD protein (CC16; an inhibitor of neutrophil chemotaxis), angiogenin (an inhibitor of degranulation), and the total radical oxygen neutralizing activity with the amount of elastase (a marker of neutrophil activation) and with the Pao2/Fio2 ratio, which is inversely related to lung injury.

SETTING

University hospital.

PATIENTS

Patients with ARDS (n = 12) and patients at risk for developing ARDS (n = 14).

INTERVENTIONS

Patients underwent bronchoalveolar lavage 12 hrs after diagnosis of ARDS or at-risk status.

MEASUREMENTS AND MAIN RESULTS

The amount of CC16 and radical oxygen neutralizing activity was not significantly different in patients with or at risk for ARDS. In contrast, the amount (mean +/- sem) of angiogenin in the bronchoalveolar lavage of ARDS patients (45 +/- 14 ng/mL, n = 12) was increased 11-fold (p <.05) compared with patients at risk for ARDS (4 +/- 1 ng/mL, n = 14). In patients with ARDS, the amount of protein and angiogenin in bronchoalveolar lavage increased with decreasing concentration of CC16 (p <.05). In addition, CC16 correlated with the Pao2/Fio2 ratio (p <.05) and inversely with the amount of elastase (p <.05) and thus may be regarded as a reliable protective agent for lung injury.

CONCLUSION

A high concentration of CC16, a natural inhibitor of neutrophil function, decreases neutrophil-mediated lung damage of patients with ARDS. Strategies to increase natural anti-inflammatory agents, and thus influence the disruption of the balance between natural inflammatory and anti-inflammatory or protective factors, could be useful to modulate the tissue destruction and the course of ARDS.

Twin chorionicity and pre-eclampsia

OBJECTIVE

To determine whether the incidence of pre-eclampsia is different in dichorionic compared to monochorionic twin pregnancies.

METHODS

The study involved 666 twin pregnancies resulting in two live births after 24 weeks of gestation. Ultrasound examination at 10-14 weeks of gestation demonstrated that 171 (25.7%) were monochorionic and 495 (74.3%) were dichorionic twins. Pregnancy outcome information regarding the development of pre-eclampsia was obtained from the maternity units. The incidence of pre-eclampsia in the dichorionic and monochorionic twin pregnancies was compared.

RESULTS

The incidence of pre-eclampsia in monochorionic twin pregnancies (9.4%) was not significantly different from that in dichorionic pregnancies (7.3%) ( P = 0.48). Multiple logistic regression revealed that chorionicity has no effect on the development of pre-eclampsia after adjusting for maternal age, ethnic group, maternal smoking, parity and gestational age at delivery ( P = 0.6; odds ratio for monochorionic compared with dichorionic twin pregnancies, 1.19; 95% confidence interval, 0.61-2.3).

CONCLUSION

In twin pregnancies chorionicity does not affect the incidence of pre-eclampsia.

First trimester maternal serum placenta growth factor (PIGF)concentrations in pregnancies with fetal trisomy 21 or trisomy 18

Placenta growth factor (PIGF), an angiogenic factor belonging to the vascular endothelial growth factor family, pregnancy-associated plasma protein A (PAPP-A) and free beta-human chorionic gonadotrophin (beta-hCG) were measured in maternal serum from 45 pregnancies with trisomy 21, 45 with trisomy 18 and 493 normal controls at 10-13 completed weeks of gestation. In the normal pregnancies maternal serum PIGF levels increased exponentially with gestation. The median multiple of the median (MoM) PIGF concentration in the trisomy 21 group (1.26 MoM) was significantly higher (p<0.0001) than in the control group (1.00 MoM). In the trisomy 18 group the median PIGF was lower (0.889 MoM) but this did not quite reach significance (p=0.064). The corresponding median MoM values for PAPP-A were 1.00 MoM for the controls, 0.49 MoM for trisomy 21 and 0.16 MoM for trisomy 18. The median MoM values for free beta-hCG were 1.00 MoM for the controls, 2.05 MoM for trisomy 21 and 0.38 MoM for trisomy 18. In the control group there was a small but significant correlation of PIGF with free beta-hCG (r=+0.1024) and PAPP-A (r=+0.2288). In the trisomy 18 group there was a significant association between PIGF and free beta-hCG (r=+0.2629) but not with PAPP-A (r=+0.0038). In the trisomy 21 group there was a small but significant association with PAPP-A (r=+0.1028) but not with free beta-hCG (r=+0.0339). The separation of affected and unaffected pregnancies in maternal serum PIGF is small, and therefore it is unlikely that measurement of PIGF would improve screening for these abnormalities provided by the combination of fetal nuchal translucency and maternal serum PAPP-A and free beta-hCG.

Development of reverse transcriptase PCR assays for detection of active human herpesvirus 6 infection

We developed reverse transcriptase (RT) PCR assays for the detection of mRNA from three spliced genes of human herpesvirus 6 (HHV-6), the immediate-early genes U16/U17 and U89/U90 and the late gene U60/U66. Sequence analysis determined the splicing sites of these genes. The new assays may be instrumental in investigating the association between HHV-6 and disease.

Maternal serum levels of dimeric inhibin A in pregnancies affected by trisomy 21 in the first trimester

Dimeric inhibin A was measured in maternal serum samples from 45 pregnancies affected by trisomy 21 and 493 samples from unaffected pregnancies at 10-14 weeks of gestation. Inhibin A levels in affected pregnancies were compared with levels of free beta-hCG and PAPP-A in the same series. In the trisomy 21 group, the median multiple of the median (MoM) inhibin A was not significantly elevated (1.28 vs 1.00) with only 15.5% being above the 95th centile. In contrast, the median MoM free beta-hCG was significantly increased (2.05 vs 1.00) with 36% above the 95th centile and PAPP-A was significantly reduced (0.49 vs 1.00) with 42% below the 5th centile. Inhibin A levels in the trisomy 21 group were significantly correlated with gestational age such that median levels rose from 1.04 at 11 weeks to 1.30 at 12 weeks and 1.67 at 13 weeks. These findings suggest that first trimester biochemical screening for trisomy 21, which is currently optimised using maternal serum free beta-hCG and PAPP-A and fetal nuchal translucency, will not benefit from the inclusion of inhibin A.

Fetal heart rate in chromosomally abnormal fetuses

OBJECTIVES

To determine the effects of chromosomal defects on fetal heart rate at 10-14 weeks of gestation.

METHODS

Fetal heart rate at 10-14 weeks of gestation in 1061 chromosomally abnormal fetuses was compared to that from 25,000 normal pregnancies. The chromosomally abnormal group included 554 cases of trisomy 21, 219 cases of trisomy 18, 95 of trisomy 13, 50 of triploidy, 115 of Turner syndrome and 28 of sex chromosome abnormalities other than Turner syndrome.

RESULTS

In the normal group, fetal heart rate decreased from a mean value of 170 beats per minute (bpm) at 35 mm of crown-rump length to 155 bpm at 84 mm crown-rump length. In trisomy 21, trisomy 13 and Turner syndrome fetal heart rate was significantly higher, in trisomy 18 and triploidy the heart rate was lower and in other sex chromosome defects it was not significantly different from normal. Fetal heart rate was above the 95th centile of the normal range in 10%, 67% and 52% of fetuses with trisomy 21, trisomy 13 and Turner syndrome, respectively. The fetal heart rate was below the 5th centile in 30% of fetuses with triploidy and 19% of those with trisomy 18.

CONCLUSIONS

Trisomy 21, trisomy 13 and Turner syndrome are associated with fetal tachycardia, whereas in trisomy 18 and triploidy there is fetal bradycardia. Inclusion of fetal heart rate in a first-trimester screening program for trisomy 21 by a combination of maternal age and fetal nuchal translucency thickness is unlikely to provide useful improvement in sensitivity.