Symphysis-fundus height, maternal height, labor pattern, and mode of delivery

Intrapartum sonographic assessment of the fetal head flexion in protracted active phase of labor and association with labor outcome: a multicenter, prospective study

BACKGROUND

To date, no research has focused on the sonographic quantification of the degree of flexion of the fetal head in relation to the labor outcome in women with protracted active phase of labor.

OBJECTIVE

This study aimed to assess the relationship between the transabdominal sonographic indices of fetal head flexion and the mode of delivery in women with protracted active phase of labor.

STUDY DESIGN

Prospective evaluation of women with protracted active phase of labor recruited across 3 tertiary maternity units. Eligible cases were submitted to transabdominal ultrasound for the evaluation of the fetal head position and flexion, which was measured by means of the occiput-spine angle in fetuses in nonocciput posterior position and by means of the chin-to-chest angle in fetuses in occiput posterior position. The occiput-spine angle and the chin-to-chest angle were compared between women who had vaginal delivery and those who had cesarean delivery. Cases where obstetrical intervention was performed solely based on suspected fetal distress were excluded.

RESULTS

A total of 129 women were included, of whom 43 (33.3%) had occiput posterior position. Spontaneous vaginal delivery, instrumental delivery, and cesarean delivery were recorded in 66 (51.2%), 17 (13.1%), and 46 (35.7%) cases, respectively. A wider occiput-spine angle was measured in women who had vaginal delivery compared with those submitted to cesarean delivery owing to labor dystocia (126±14 vs 115±24; P<.01). At the receiver operating characteristic curve, the area under the curve was 0.675 (95% confidence interval, 0.538-0.812; P<.01), and the optimal occiput-spine angle cutoff value discriminating between cases of vaginal delivery and those delivered by cesarean delivery was 109°. A narrower chin-to-chest angle was measured in cases who had vaginal delivery compared with those undergoing cesarean delivery (27±33 vs 56±28 degrees; P<.01). The area under the curve of the chin-to-chest angle in relation to the mode of delivery was 0.758 (95% confidence interval, 0.612-0.904; P<.01), and the optimal cutoff value discriminating between vaginal delivery and cesarean delivery was 33.0°.

CONCLUSION

In women with protracted active phase of labor, the sonographic demonstration of fetal head deflexion in occiput posterior and in nonocciput posterior fetuses is associated with an increased incidence of cesarean delivery owing to labor dystocia. Such findings suggest that intrapartum ultrasound may contribute in the categorization of the etiology of labor dystocia.

Gestational Weight Gain: Historical Evolution of a Contested Health Outcome

The history of research on gestational weight gain (GWG) in the United States and United Kingdom provides a context for current clinical practice. We trace the evolution of research on GWG in scientific literature from the 19th century to the present and examine its implications for contemporary clinical and public health practice. Obstetricians, beginning in the late 1800s, recommended dieting during pregnancy in order to limit GWG to 20 lb or less, driven by a belief that excessive weight gain was a cause of toxemia. Beginning in the 1930s, a burgeoning focus on nutrition and health allowed a better understanding of the effect of GWG on the health of the fetus and the newborn. Increased awareness of disparities in infant mortality in the 1960s, followed by systematic review of the literature, produced further refinements in GWG recommendations in the 1970s, which continue today. Current research focuses on epigenetic influences over the life course and has emphasized individualized recommendations. The complex historical perspective that this article provides serves as a reminder of both the interplay and the gaps between research and practice. These gaps result from the fact that clinical guidelines often reflect a specific point in a perpetually evolving state of knowledge that is influenced not only by advances in bench research, but also by refinements in statistical and epidemiologic methods, as well as by the political realities of the time in which they are drafted.

Importance

Gestational weight gain and its relationship to maternal, fetal, and infant health are areas of active inquiry.

Objective

We critically review evolution of scientific understanding of GWG from the 19th century to the present, and examine its implications for contemporary obstetric practice.

Evidence Acquisition

We reviewed all English-language medical studies related to GWG published through 1930s as well as widely cited influential works from 1940s through present time.

Results

During the past century, recommendations for GWG have reversed from emphasizing dieting during pregnancy to the importance of proper nutrition during pregnancy. Obstetricians' focus has also evolved from being exclusively on the newborn to include the health of mothers. Contemporary obstetric practice seeks to achieve a balance between mothers' and infants' risk of adverse outcomes.

Conclusions

Historical and social contexts of the United States and the United Kingdom led to distinct GWG policies in the 2 countries. Changes in GWG recommendations over the past century reflect developments in the allied fields, such as epidemiology and nutrition, as much as progress in obstetrics and gynecology.

Relevance

The complex historical perspective that this article provides serves as a reminder of both the interplay and the gaps between research and practice. These gaps result from the fact that clinical guidelines often reflect a specific point in a perpetually evolving state of knowledge that is influenced not only by advances in bench research, but also by refinements in statistical and epidemiologic methods, as well as by the political realities of the time in which they are drafted.

Cesarean section indications and anthropometric parameters in Rwandan nulliparae: preliminary results from a longitudinal survey

INTRODUCTION

Maternal anthropometric parameters as risk factors for cesarean section have always been a matter of interest and concern for obstetricians. Some of these parameters have been shown to be predictors of dystocia. This study aims at showing the relationship between cesarean section indications and anthropometric parameters sizes in Rwandan nulliparae for the purpose of comparison and appropriate recommendations.

METHODS

A cross-sectional and analytical study was made on data collected from 32 operated patients among 152 nulliparae with singleton pregnancy at term and vertex presentation. Concerned anthropometric parameters were height, weight and six pelvic distances. Fisher exact and Student's tests were used to compare observed proportions and mean values, respectively.

RESULTS

Findings were as follows: 1) the overall cesarean section rate was 21.05%; 2) acute fetal distress (31.3 %), generally contracted pelvis (28.1 %), and engagement failure (25%) were the most frequent indications of cesarean section; 3) all patients ≤ 145 cm tall were operated on for general pelvis contraction whose proportion was significantly higher in them than in the others (p < 0.01); 4) more than half of pelvis contraction cases were observed in patients weighing ≤ 50 kg, but the difference with other weight categories was not significant; 5) considered external pelvic diameters but the Biiliac Diameter displayed average measurements smaller in clinically contracted pelvis than in other CS indications.

CONCLUSION

External pelvimetry associated with specific other anthropometric parameters could be helpful in the screening of generally contracted pelves, and consequently pregnancies at high risk of cephalopelvic disproportion in nulliparous women, particularly in developing countries with limited resources. Further investigations are requested to deal with this topic in depth.

The diagnostic accuracy of external pelvimetry and maternal height to predict dystocia in nulliparous women: a study in Cameroon

OBJECTIVE

In many developing countries, most women deliver at home or in facilities without operative capability. Identification before labour of women at risk of dystocia and timely referral to a district hospital for delivery is one strategy to reduce maternal and perinatal mortality and morbidity. Our objective was to assess the prediction of dystocia by the combination of maternal height with external pelvimetry, and with foot length and symphysis-fundus height.

DESIGN

A prospective cohort study.

SETTING

Three maternity units in Yaoundé, Cameroon.

POPULATION

A total of 807 consecutive nulliparous women at term who completed a trial of labour and delivered a single fetus in vertex presentation.

METHODS

Anthropometric measurements were recorded at the antenatal visit by a researcher and concealed from the staff managing labour. After delivery, the accuracy of individual and combined measurements in the prediction of dystocia was analysed.

MAIN OUTCOME MEASURES

Dystocia, defined as caesarean section for dystocia; vacuum or forceps delivery after a prolonged labour (>12 hours); or spontaneous delivery after a prolonged labour associated with intrapartum death.

RESULTS

Ninety-eight women (12.1%) had dystocia. The combination of a maternal height less than or equal to the 5th percentile or a transverse diagonal of the Michaelis sacral rhomboid area less than or equal to the 10th percentile resulted in a sensitivity of 53.1% (95% CI 42.7-63.2), a specificity of 92.0% (95% CI 89.7-93.9), a positive predictive value of 47.7% (95% CI 38.0-57.5) and a positive likelihood ratio of 6.6 (95% CI 4.8-9.0), with 13.5% of all women presumed to be at risk. Other combinations resulted in inferior prediction.

CONCLUSION

The combination of the maternal height with the transverse diagonal of the Michaelis sacral rhomboid area could identify, before labour, more than half of the cases of dystocia in nulliparous women.

Maternal height and the outcome of labor in rural Tanzania

The influence of maternal height (standardized for parity and birthweight) on obstetrical outcome is studied in 1095 women giving birth in Lugarawa hospital and 3869 women delivering in Mbozi hospital, both rural hospitals in the South Western Highlands of Tanzania. Short stature was found to increase the need for augmentation of labor in primiparae, the need for operative delivery (cesarean section/symphyseotomy) in all parity groups and the need for vacuum extraction in multiparae. The absence of such an effect of height on perinatal mortality is interpreted as the result of obstetric intervention. It is concluded that maternal height, which is easy to measure, remains a useful tool to predict difficult childbirth and cephalopelvic disproportion.

Customised gravidogram and fetal growth chart in a South African population

OBJECTIVE

To investigate whether gravidograms and fetal growth curves should be customized, i.e. tailor made for a specific ethnic group.

METHODS

A cross-sectional study of 800 pregnant Xhosa women attending antenatal care in the Eastern Cape Province (South Africa). The data measured was used to compare the correlation between the symphysis-fundus height measurement (SFHM) and the sonographic estimate of gestational age (SEGA), as well as the intra-uterine fetal growth curve with existing gravidograms and fetal growth charts.

RESULTS

There was a good correlation between the SFHM and the SEGA: r = 0.91 (P < 0.0001). The correlation between the SFHM and the sonographic estimate of fetal weight (SEFW) yielded a correlation coefficient (r) of 0.40 (P < 0.0001). The correlation between the SEFW and SEGA resulted in a r = 0.97 (P < 0.0001). The customized gravidogram and fetal growth chart followed the general trend seen in their Caucasian equivalents.

CONCLUSION

The comparison of our customized gravidogram and intra-uterine fetal growth curve with similar charts established in Caucasians does not show any significant difference.

The relation between height, foot length, pelvic adequacy and mode of delivery

OBJECTIVE

To investigate the value of maternal height and foot length as predictors of pelvic adequacy and to evaluate the influence of body components' proportions on the mode of delivery.

METHODS

Retrospective study of the anthropometry of women having normal vertex deliveries (NVD), caesarean sections (CS) and vaginal birth after caesarean (VBAC).

RESULTS

NVD patients were taller, had a longer vertebral column, longer lower limbs and longer feet than CS and than VBAC patients. The anthropometric measurements of VBAC patients yielded values intermediate between CS and NVD patients. The ratios of height to any of the other measured variables (vertebral column, lower limb and foot length) were similar in the three groups indicating that the body proportions were the same.

CONCLUSION

Maternal height and foot length are of limited value as predictors of pelvic (in-)adequacy. The anthropometric features of women delivered by CS only are similar to those of women having a vaginal birth after Caesarean.

The value of maternal height as a risk factor of dystocia: a meta-analysis

Ten publications and studies on the relation between maternal height and the risk of dystocia due to cephalopelvic disproportion (CPD) are analysed. The rate of Caesarean sections was chosen as the CPD indicator. When maternal height is presented in percentiles, curves can be superimposed, and sensitivities and specificities of the various studies may be analysed together. One biased study was excluded; the remaining 9 were pooled and regression lines calculated for sensitivity (Se) and specificity (Sp) of the entire set of points. The resulting model, i.e. Se = 10.9 + 1.99 Y and Sp = 99.9 - 0.99 Y, permits easy calculation of the expected sensitivity and specificity for each percentile Y. When the frequency of Caesarean section due to CPD is known, positive and negative predictive values can also be calculated. The proposed formulas can also be used to determine confidence intervals. The findings in terms of the sensitivity and specificity of low maternal height as a risk factor for dystocia indicate that 1 out of 5 pregnant women would have to be referred for further investigation to identify half of the cases of mechanical dystocia necessitating Caesarean section. The predictive value for a Caesarean rate of 2% (a value often seen in developing countries) for this 20th percentile would be only 5%. Practical ways of choosing a reference criterion are suggested. A two-track strategy (antenatal check-ups and community monitoring) is proposed.

Prenatal predictors of cesarean section due to labor arrest

Cesarean section due to labor arrest occurs because the fetus is too large for the maternal outlet tract. If these women could be identified prior to labor, patient management could be optimized for both the clinician and the woman. A case-control study was designed to identify predictors of Cesarean section due to labor arrest. A five year retrospective review identified 32 cases and 329 controls with complete data for the prenatal maternal variables. Both cases and controls were considered for the stepwise logistic regression model. The prenatal variables predicting Cesarean section due to labor arrest are parity, history of past macrosomia, maternal age, term fundal height and maternal height. This model can be considered a pilot model that can be tested in a large international/inter-ethnic population.

Prediction of caesarean section from ultrasound and clinical assessment of fetal size

One hundred and five women with singleton pregnancies and cephalic presentation were assessed. Fundal height and a clinical estimate of fetal weight were recorded. The fetal biparietal diameter, abdominal circumference and femur length were measured with ultrasound. Ultrasound estimated fetal weight was calculated using 3 different formulas (Shepard, Campbell and CUHK). The liquor volume was assessed using the amniotic fluid index. Ultrasound was able to predict Caesarean section with more reliability than clinical assessment of fetal size or weight. The biparietal diameter, fundal height and amniotic fluid index were poor predictors of mode of delivery. The measurements which best predicted the mode of delivery were the fetal femur length and abdominal circumference. Femur length, but not abdominal circumference, was a statistically better predictor of Caesarean section than clinical estimation of fetal weight. There was no improvement in prediction using ultrasound estimated fetal weight.

Prediction of fetal growth deviations by use of symphysis-fundus height measurements

The development of various symphysis fundus (SF) growth charts and the use of SF height measurements in the diagnosis of small-for-gestational-age (SGA) births and the prediction of newborn complications are reviewed. Measurement precision and accuracy are also discussed. It is concluded that further research of this simple, low cost, harmless, and widespread technology to detect fetal growth disturbances in routine prenatal care is warranted.

Variability of symphysis-fundus height measurements: an experimental study among general practitioners

With the aim of evaluating the impact of supervised training during a postgraduate course in obstetrics and gynaecology, the variability of symphysis-fundus (SF) height measurements was studied by a group of general practitioners (GPs), all of whom provided primary antenatal care. A nested analysis of variance was used. The SF height measurements of the group differed significantly from those of a senior obstetrician and the course training had no impact on the variability. Similar studies should evaluate measurement variability in the light of pregnancy outcome.