Birth weight as a predictor of brachial plexus injury

A systematic review of brachial plexus injuries after caesarean birth: challenging delivery?

BACKGROUND

Caesarean section (CS) is widely perceived as protective against obstetric brachial plexus injury (BPI), but few studies acknowledge the factors associated with such injury. The objectives of this study were therefore to aggregate cases of BPI after CS, and to illuminate risk factors for BPI.

METHODS

Pubmed Central, EMBASE and MEDLINE databases were searched using free text: ("brachial plexus injury" or "brachial plexus injuries" or "brachial plexus palsy" or "brachial plexus palsies" or "Erb's palsy" or "Erb's palsies" or "brachial plexus birth injury" or "brachial plexus birth palsy") and ("caesarean" or "cesarean" or "Zavanelli" or "cesarian" or "caesarian" or "shoulder dystocia"). Studies with clinical details of BPI after CS were included. Studies were assessed using the National Institutes for Healthy Study Quality Assessment Tool for Case Series, Cohort and Case-Control Studies.

MAIN RESULTS

39 studies were eligible. 299 infants sustained BPI after CS. 53% of cases with BPI after CS had risk factors for likely challenging handling/manipulation of the fetus prior to delivery, in the presence of considerable maternal or fetal concerns, and/or in the presence of poor access due to obesity or adhesions.

CONCLUSIONS

In the presence of factors that would predispose to a challenging delivery, it is difficult to justify that BPI could occur due to in-utero, antepartum events alone. Surgeons should exercise care when operating on women with these risk factors.

Macrosomia Risk Factors and Perinatal Outcomes: A 1-year Cohort Study

AIM: This study aims to identify possible risk factors and concurrently investigates how macrosomia impacts mothers and neonates. STUDY DESIGN: The study is a retrospective cohort of data obtained in a large tertiary obstetrics and neonatal unit over 1 year, from anuary 1, 2019 to December 31, 2019. Data of all deliveries conducted at the institution were accessed. In addition, singleton and term pregnancies were included for further analysis. Multiple pregnancies, premature births, stillbirths, non-vertex presentations, and being lost to follow-up served as exclusion criteria. A database of the cases was constructed and data regarding maternal constitutional parameters, mode of delivery, shoulder dystocia, perineal trauma, and postpartum hemorrhage were collected. Further on, pregnancies were divided accordingly into two groups: Macrosomic fetuses (>4000 g) and non-macrosomic fetuses (<4000 g). The two groups were compared to assess possible macrosomia risk factors and maternal-neonatal outcomes. Statistical analysis is done using the Mann–Whitney-U and Chi-square tests. Significance was set as p < 0.05. RESULTS: A total of 3408 deliveries met the inclusion criteria of the study. The macrosomia rate is 10.3%. The mean age (30.1 ± 5.17 years vs. 28.9 ± 8.4 years, p < 0.05) and, body mass index (29.2 ± 3.54 vs. 26.1 ± 2.78, p < 0.05) was significantly higher in the macrosomia group. Women that gained more than 12.5 kg have nearly twice the odds of delivering a big baby (odds ratio [OR] 1.86, confidence interval [CI] 1.47–2.36, p < 0.001). No statistically significant differences were noted regarding cases of gestational diabetes (p = 0.56). Cesarean sections were preferred to vaginal deliveries in the macrosomic group (39.3% vs. 29.7%, OR 1.53, CI 1.2–1.9, p = 0.001). The risk of undergoing an emergency procedure is 6-fold higher in pregnancies with macrosomic newborns (20.5% vs. 13.6%, OR 6.1, CI 4.45–8.36, p < 0.001). Both episiotomy rate (40.45% vs. 31.9%, OR 1.44, CI 1.15–1.81, p = 0.001) and lacerations (3.13 % vs. 1.44%, OR 2.21, CI 1.13–4.33, p = 0.02) were higher in the macrosomic group. CONCLUSION: The study concludes that macrosomia is associated with an increase in maternal and neonatal adverse outcomes.

Increased incidence of shoulder dystocia but a declining incidence of obstetric brachial plexus palsy in vaginally delivered infants

INTRODUCTION

Obstetric brachial plexus palsy (OBPP) is a serious form of neonatal morbidity. The primary aim of this population-based registry study was to examine temporal trends, 1997-2019, of OBPP in infants delivered vaginally in a cephalic presentation. The secondary aim was to examine temporal changes in the incidence of associated risk factors.

MATERIAL AND METHODS

This was a population-based registry study including singleton, cephalic, vaginally delivered infants, 1997-2019, in Sweden. To compare changes in the incidence rates of OBPP and associated risk factors over time, univariate logistic regression was used and odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

The incidence of OBPP in infants delivered vaginally in a cephalic presentation decreased from 3.1 per 1000 births in 1997 to 1.0 per 1000 births in 2019 (OR 0.31, 95% CI 0.24-0.40). Conversely, the incidence of shoulder dystocia increased from 2.0 per 1000 in 1997 to 3.3 per 1000 in 2019 (OR 1.64, 95% CI 1.34-2.01). Over time, the proportion of women with body mass index of 30 kg/m² or greater increased (14.5% in 2019 compared with 8.0% in year 1997, OR 1.96, 95% CI 1.89-2.03), more women had induction of labor (20.5% in 2019 compared with 8.6% in 1997, OR 2.74, 95% CI 2.66-2.83) and epidural analgesia (41.2% in 2019 compared with 29.0% in 1997, OR 1.72, 95% CI 1.68-1.75). In contrast, there was a decrease in the rate of operative vaginal delivery (6.0% in 2019, compared with 8.1% in 1997, OR 0.72, 95% CI 0.69, 0.75) and in the proportion of infants with a birthweight greater than 4500 g (2.7% in 2019 compared with 3.8% in 1997, OR 0.70, 95% CI 0.66-0.74). The decline in the incidence of these two risk factors explained only a small fraction of the overall decrease in OBPP between 1997-2002 and 2015-219.

CONCLUSIONS

The incidence of OBPP in vaginally delivered infants in a cephalic presentation at birth decreased during the period 1997-2019 despite an increase in important risk factors including shoulder dystocia.

Short- and Long-Term Outcomes Associated with Large for Gestational Age Birth Weight

Large for gestational age birth weight is associated with adverse short- and long-term outcomes. Infants born with large for gestational age birth weight are at increased risk for neonatal intensive care unit admission, respiratory distress, neonatal metabolic abnormalities including hypoglycemia, birth trauma, and even stillbirth or neonatal death. The risk for many of these complications increases with higher birth weights. Individuals with large for gestational age birth weight also appear to be at subsequent increased risk for overweight/obesity, diabetes, cardiovascular disease, and even some childhood cancers. These data highlight the need for effective interventions to decrease risk across the lifespan.

Macrosomic Newborns Delivered at Term after Labor among Nondiabetic Women: Maternal and Neonatal Morbidities

OBJECTIVE

This study aimed to compare morbidities among nonmacrosomic versus macrosomic singleton live births of nondiabetic women who labored.

STUDY DESIGN

This retrospective study utilized the 2003 revision of U.S. birth certificate data of singleton live births (2011-2013) at 37 to 41 weeks who labored. The primary outcomes were composite maternal and neonatal morbidities (CMM and CNM, respectively). We compared these outcomes by birth weight, 2,500 to 3,999 g (group 1; reference), 4,000 to 4,449 g (group 2), and 4,500 to 5,999 g (group 3). We used multivariable Poisson regression analyses to examine the association between birth weight groups and the outcomes.

RESULTS

Among 6,691,338 live births, 92.0% were in group 1, 7.1% in group 2, and 0.9% in group 3. The overall CMM and CNM rates were 4.4 and 6.8 per 1,000 live births, respectively. Compared with group 1, the risk of CMM was significantly higher in group 2 (adjusted risk ratio [aRR] = 1.50; 95% confidence interval [CI]: 1.44-1.56) and group 3 (aRR = 2.00; 95% CI: 1.82-2.19). Likewise, the risk of CNM was significantly higher in group 2 (aRR = 1.38; 95% CI: 1.33-1.43) and group 3 (aRR = 2.57; 95% CI: 2.40-2.75) than in group 1.

CONCLUSION

Nondiabetic women who labor with a macrosomic newborns have a significantly higher rate of adverse outcomes than nonmacrosomic.

Risk factors for neonatal brachial plexus palsy: a systematic review and meta-analysis

AIM

To provide a comprehensive update on the most prevalent, significant risk factors for neonatal brachial plexus palsy (NBPP).

METHOD

Cochrane CENTRAL, MEDLINE, Web of Science, Embase, and ClinicalTrials.gov were searched for relevant publications up to March 2019. Studies assessing risk factors of NBPP in relation to typically developing comparison individuals were included. Meta-analysis was performed for the five most significant risk factors, on the basis of the PRISMA statement and MOOSE guidelines. Pooled odds ratios (ORs), 95% confidence intervals (CIs), and across-study heterogeneity (I² ) were reported. Reporting bias and quality of evidence was rated. In addition, we assessed the incidence of NBPP.

RESULTS

Twenty-two observational studies with a total sample size of 29 419 037 live births were selected. Significant risk factors included shoulder dystocia (OR 115.27; 95% CI 81.35-163.35; I² =92%), macrosomia (OR 9.75; 95% CI 8.29-11.46; I² =70%), (gestational) diabetes (OR 5.33; 95% CI 3.77-7.55; I² =59%), instrumental delivery (OR 3.8; 95% CI 2.77-5.23; I² =77%), and breech delivery (OR 2.49; 95% CI 1.67-3.7; I² =70%). Caesarean section appeared as a protective factor (OR 0.13; 95% CI 0.11-0.16; I² =41%). The pooled overall incidence of NBPP was 1.74 per 1000 live births. It has decreased in recent years.

INTERPRETATION

The incidence of NBPP is decreasing. Shoulder dystocia, macrosomia, maternal diabetes, instrumental delivery, and breech delivery are risk factors for NBPP. Caesarean section appears as a protective factor.

WHAT THIS PAPER ADDS

The overall incidence of neonatal brachial plexus palsy is 1.74 per 1000 live births. The incidence has declined significantly. Shoulder dystocia, macrosomia, maternal diabetes, instrumental delivery, and breech delivery are the main risk factors. Prevention is difficult owing to unpredictability and often labour-related risk.

Identification of newborns with birthweight ≥ 4,500g: Ultrasound within one- vs. two weeks of delivery

OBJECTIVE

Our objective was to compare the diagnostic characteristics of sonographic estimated fetal weight (SEFW) done within 7 versus 8-14 days before delivery for detection of fetal macrosomia (birthweight ≥ 4500 g).

STUDY DESIGN

We performed a multicenter, retrospective cohort study of all non-anomalous singletons with SEFW ≥ 4000 g by Registered Diagnostic Medical Sonographers conducted within 14 days of delivery. Cohorts were grouped by time interval between ultrasound and delivery: 0-7 days versus 8-14 days. The detection rate (DR) and false positive rate (FPR) for detection of birthweight (BW) ≥ 4500 g were compared between groups with subgroup analysis for diabetic women. Area under the receiver operator curve (AUC) was calculated to analyze all possible SEFW cutoffs within our cohort.

RESULTS

A total of 330 patients met inclusion criteria with 250 (75.8 %) having SEFW within 7 days and 80 (24.2 %) with SEFW 8-14 days prior to delivery. The rate of macrosomia was 15.1 % (N = 51). The DR for macrosomia was significantly higher when SEFW was performed within 7 days of delivery compared to 8-14 days among non-diabetic (73.0 % vs 7.1 %; p < 0.001) and diabetic women (76.5 % vs 16.7 %; p = 0.02). There was no significant change in FPR in either group. The AUC for detection of macrosomia was significantly higher when SEFW was performed within 7 days versus 8-14 days (0.89 vs 0.63; p < 0.01).

CONCLUSION

With SEFW ≥ 4000 g, the detection of BW ≥ 4500 g is significantly higher when the sonographic examination is within 7 days of birth irrespective of maternal diabetes.

Maternal and Neonatal Morbidity Associated With Early Term Delivery of Large-for-Gestational-Age But Nonmacrosomic Neonates

OBJECTIVE

To evaluate whether, at 37-39 weeks of gestation, delivery of a neonate with a birth weight that is 90% or greater for gestational age but less than 4,000 g is associated with increased composite maternal and neonatal morbidity.

METHODS

This retrospective cohort study used U.S. Vital Statistics datasets for the years 2011-2013. Inclusion criteria were singleton pregnancies delivered at 37-39 weeks of gestation after labor in which the neonates were nonanomalous, and either appropriate for gestational age or large for gestational age (LGA) neonates with birth weights of less than 4,000 g (our threshold for macrosomia). The coprimary outcomes were composite maternal morbidity (any of the following: maternal transfusion, ruptured uterus, unplanned hysterectomy, admission to intensive care unit, or unplanned procedure) and composite neonatal morbidity (any of the following: Apgar score less than 5 at 5 minutes, assisted ventilation for more than 6 hours, seizure or serious neurologic dysfunction, significant birth injury or neonatal mortality). Multivariable Poisson regression models were used to calculate adjusted relative risk (aRR) and 95% CI.

RESULTS

Among the 3.9 million women who met inclusion criteria, 1.3% delivered neonates who were LGA but nonmacrosomic. The rate of composite maternal morbidity was 53% higher women who delivered nonmacrosomic LGA neonate (6.27 vs 4.09/1,000 live births; aRR 1.40, 95% CI 1.25-1.56). This increased risk of composite maternal morbidity persisted in analyses stratified by diabetes. The rate of composite neonatal morbidity was 83% higher for nonmacrosomic LGA neonates (11.09 vs 6.07/1,000 live births; aRR 1.47, 95% CI 1.35-1.60) and persisted in analyses stratified by diabetes.

CONCLUSION

At 37-39 weeks of gestation, delivery of a neonate with a birth weight that is 90% or greater for gestational age but less than 4,000 g is associated with increased composite maternal and neonatal morbidity.

Time and mode of delivery in diabetic pregnancy: a review

The review presents some renewed data on the problem of optimal time and modes of delivery for women with various types of diabetes mellitus (DM 1 and 2, gestational diabetes). The necessity of making the universal delivery strategy algorithm for women with DM comes out of adverse outcomes high frequency, where the main cases are fetal macrosomia, fetal shoulder dystocia and perinatal mortality. Despite significant interest for this issue, there is still no common delivery tactics in the world for pregnant women with carbohydrate metabolism disorders. The main obstacle is evidence-based tests and meta-analysis insufficiency. So far, further studies are necessary to obtain high quality data concerning optimal terms and modes of delivery for women with DM.

Birthweight thresholds for increased risk for maternal and neonatal morbidity following vaginal delivery: a retrospective study

PURPOSE

To determine neonatal birthweight (BW) thresholds for adverse maternal and neonatal outcome following vaginal delivery.

METHODS

A retrospective cohort study of all women with singleton pregnancies who underwent vaginal delivery in a university-affiliated tertiary hospital (1996-2015). The association between BW and adverse outcome in neonates with BW ≥ 3500 g (> 90th centile BW at 37 weeks' gestation) with 100 g-increment groups was explored. Pregnancies complicated by diabetes mellitus, fetal anomalies or cesarean deliveries were excluded. The composite neonatal outcome was defined as shoulder dystocia or brachial plexus injury. The composite maternal outcome was defined as postpartum hemorrhage or third- or fourth-degree perineal tears.

RESULTS

Of the 121,728 deliveries during the study period, 26,920 (22.1%) met inclusion criteria. Of these, 1024 (3.8%) had a composite adverse maternal outcome and 947 (3.5%) had a composite adverse neonatal outcome. The rates of composite maternal outcomes increased significantly only at a BW of 4800 g and above. The composite neonatal outcomes increased significantly only at a BW of 4400 g and above. In multivariate analysis, after subcategorizing our cohort into 3 BW groups [3500-3999 g (control, n = 23,030); 4000-4399 g (n = 3494); ≥ 4400 g (n = 396)], BW was associated with adverse neonatal outcomes in a dose-dependent manner. In the BW ≥ 4400 g group, to prevent one case of shoulder dystocia or Erb's palsy, 12 cesarean deliveries needed to be performed.

CONCLUSION

For non-diabetic mothers who deliver vaginally, neonatal BW ≥ 4400 g was associated with a significant increase in adverse neonatal outcomes, whereas neonatal BW ≥ 4800 g was associated with a significant increase in adverse maternal outcomes.

Disadvantages of a weight estimation formula for macrosomic fetuses: the Hart formula from a clinical perspective

Purpose

Sonographic fetal weight (FW) estimation to detect macrosomic fetuses is an essential part of everyday routine work in obstetrics departments. Most of the commonly used weight estimation formulas underestimate FW when the actual birth weight (BW) exceeds 4000 g. One of the best-established weight estimation formulas is the Hadlock formula. In an effort to improve the detection rates of macrosomic infants, Hart et al. published a specially designed formula including maternal weight at booking. The usefulness of the Hart formula was tested.

Methods

Retrospective study of 3304 singleton pregnancies, birth weight ≥ 3500 g. The accuracy of the Hadlock and Hart formula were tested. A subgroup analysis examined the influence of the maternal weight. The Chi-squared test and one-way analysis of variation were carried out. For all analyses, p < 0.05 was considered statistically significant.

Results

The overall percentages of births falling within ± 5% and ± 10% of the BW using the Hadlock formula were 27% and 53%, respectively. Using the Hart formula, 24% and 54% were identified within these levels. With the Hart formula, 94% of all weight estimations fall within 4200 g ± 5% and nearly 100% fall within 4200 g ± 10%.

Conclusions

Applying the Hart formula results in an overestimation of fetal weight in neonates with a birth weight < 4000 g and fails to identify high-risk fetuses. We, therefore, do not consider Hart’s formula to be of clinical relevance.

Foetal Macrosomia and Foetal-Maternal Outcomes at Birth

To investigate how macrosomia affects foetal-maternal birth outcomes, we conducted a retrospective cohort study of singleton pregnant women who gave birth at gestational age ≥37+0 weeks. The patients were divided into three groups according to birth weight: “macrosomia” group, ≥4500 g, n=285; “upper-normal” group, 3500–4499 g, n=593; and “normal” group, 2500–3499 g, n=495. Foetal-maternal and delivery outcomes were compared among the three groups after adjustment for confounders. Caesarean section was more frequent in the macrosomia group than in upper-normal and normal groups. The duration of labour (p < 0.05) and postpartum care at the hospital (p < 0.001) were the highest in the macrosomia group. Increased birth weight was associated with higher risks of shoulder dystocia (p < 0.001), increased bleeding volume (p < 0.001), and perineal tear (p < 0.05). The Apgar score at 5 minutes (p < 0.05), arterial cord pH (p < 0.001), and partial pressure of O2 (p < 0.05) were lower, while the arterial cord partial pressure of CO2 was higher (p < 0.001), in the macrosomia group. Macrosomia has potentially serious impacts for neonate and mother as a result of a complicated and occasionally traumatic delivery.

Sonographic Estimated Fetal Weight among Diabetics at ≥ 34 Weeks and Composite Neonatal Morbidity

Objectives  The objective was to assess the composite neonatal morbidity (CNM) among diabetic women with sonographic estimated fetal weight (SEFW) at 10 to 90th versus >90th percentile for gestational age (GA). Study Design  The inclusion criteria for this retrospective study were singleton pregnancies at 34 to 41 weeks, complicated by diabetes, and that had SEFW within 4 weeks of delivery. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated. Results  Among the 140 cohorts that met the inclusion criteria, 72% had SEFW at 10th to 90th percentile for GA, and 28% at >90th percentile. Compared with women with diabetes with last SEFW at 10th to 90th percentile, those with estimate > 90th percentile for GA had a significantly higher rate of CNM (13 vs. 28%; OR, 2.65; 95% CI, 1.07-6.59). Among 109 diabetic women who labored, the rate of shoulder dystocia was significantly higher with SEFW at >90th percentile for GA than those at 10th to 90th percentile (25 vs. 2%; p  = 0.002); the corresponding rate of CNM was 29 versus 10% ( p  = 0.02). Conclusion  Among diabetic women with SEFW > 90th percentile for GA, CNM was significantly higher than in women with estimate at 10 to 90th percentile. Despite the increased risk of CNM, these newborns did not have long-term morbid sequela.

Term Elective Induction of Labor and Pregnancy Outcomes Among Obese Women and Their Offspring

OBJECTIVE

To evaluate whether elective induction of labor between 39 through 41 weeks of gestation, as compared with expectant management, is associated with reduced cesarean delivery and other adverse outcomes among obese women and their offspring.

METHODS

We conducted a retrospective cohort study using the 2007-2011 California Linked Patient Discharge Data-Birth Cohort File of 165,975 singleton, cephalic, nonanomalous deliveries to obese women. For each gestational week (39-41), we used multivariable logistic regression models, stratified by parity, to assess whether elective induction of labor or expectant management was associated with lower odds of cesarean delivery and other adverse outcomes.

RESULTS

At 39 and 40 weeks of gestation, cesarean delivery was less common in obese nulliparous women who were electively induced compared with those who were expectantly managed (at 39 weeks of gestation, frequencies were 35.9% vs 41.0%, respectively [P<.05]; adjusted odds ratio [OR] 0.82, 95% CI 0.77-0.88). Severe maternal morbidity was less frequent among electively induced obese nulliparous patients (at 39 weeks of gestation, 5.6% vs 7.6% [P<.05]; adjusted OR 0.75, 95% CI 0.65-0.87). Neonatal intensive care unit admission was less common among electively induced obese nulliparous women (at 39 weeks of gestation, 7.9% vs 10.1% [P<.05]; adjusted OR 0.79, 95% CI 0.70-0.89). Patterns were similar among obese parous women at 39 weeks of gestation (crude frequencies and adjusted ORs [95% CIs] were as follows: for cesarean delivery, 7.0% vs 8.7% [P<.05] and 0.79 [0.73-0.86]; for severe maternal morbidity, 3.3% vs 4.0% [P<.05] and 0.83 [0.74-0.94]; for neonatal intensive care unit admission: 5.3% vs 7.4% [P<.05] and 0.75 [0.68-0.82]). Similarly, elective induction at 40 weeks of gestation was associated with reduced odds of cesarean delivery, maternal morbidity, and neonatal intensive care unit admission among both obese nulliparous and parous patients.

CONCLUSION

Elective labor induction after 39 weeks of gestation was associated with reduced maternal and neonatal morbidity among obese women. Further prospective investigation is necessary.

Sonographic Examination of The Fetus Vis-à-Vis Shoulder Dystocia: A Vexing Promise

Since antepartum and intrapartum risk factors are poor at identifying women whose labor is complicated by shoulder dystocia, sonographic examination of the fetus holds promise. Though there are several measurements of biometric parameters to identify the parturient who will have shoulder dystocia, none are currently clinically useful. Three national guidelines confirm that sonographic measurements do not serve as appropriate diagnostic tests to identify women who will have shoulder dystocia with or without concurrent injury. In summary, biometric measurements of the fetus should not be used to alter clinical management with the aim of averting shoulder dystocia.

Practice Bulletin No. 173: Fetal Macrosomia

Suspected fetal macrosomia is encountered commonly in obstetric practice. As birth weight increases, the likelihood of labor abnormalities, shoulder dystocia, birth trauma, and permanent injury to the neonate increases. The purpose of this document is to quantify those risks, address the accuracy and limitations of methods for estimating fetal weight, and suggest clinical management for a pregnancy with suspected fetal macrosomia.

The FL/AC ratio for prediction of shoulder dystocia in women with gestational diabetes

PURPOSE

To determine if sonographic variables, including fetal femur length to abdominal circumference (FL/AC) ratio, are associated with shoulder dystocia in women with gestational diabetes.

METHODS

This was a retrospective cohort study of women with gestational diabetes who delivered singleton infants at Parkland Hospital from 1997 to 2015. Diagnosis and treatment of gestational diabetes were uniform including sonography at 32-36 weeks. Biometric calculations were evaluated for correlation with shoulder dystocia.

RESULTS

During the study period, 6952 women with gestational diabetes underwent a sonogram at a mean gestation of 34.8 ± 1.8 weeks. Of 4183 vaginal deliveries, 66 experienced shoulder dystocia (16/1000). The FL/AC was associated with shoulder dystocia (p < 0.001) with an AUC of 0.70 (95% CI: 0.64-0.77). This was similar to age-adjusted AC and head circumference to AC ratio (HC/AC) (both with an AUC of 0.72). All other measurements, including estimated fetal weight, were inferior. When examining the 257 women with multiple sonograms after 32 weeks' gestation, FL/AC was stable with advancing gestational age (p = 0.54) whereas age-adjusted AC and HC/AC were not (p < 0.001).

CONCLUSIONS

The FL/AC is associated with shoulder dystocia in women with gestational diabetes. Additionally, it is a simple ratio that is independent of the reference used and remains stable, unlike age-adjusted AC and HC/AC ratio.

Predicting birth weight with conditionally linear transformation models

Low and high birth weight (BW) are important risk factors for neonatal morbidity and mortality. Gynecologists must therefore accurately predict BW before delivery. Most prediction formulas for BW are based on prenatal ultrasound measurements carried out within one week prior to birth. Although successfully used in clinical practice, these formulas focus on point predictions of BW but do not systematically quantify uncertainty of the predictions, i.e. they result in estimates of the conditional mean of BW but do not deliver prediction intervals. To overcome this problem, we introduce conditionally linear transformation models (CLTMs) to predict BW. Instead of focusing only on the conditional mean, CLTMs model the whole conditional distribution function of BW given prenatal ultrasound parameters. Consequently, the CLTM approach delivers both point predictions of BW and fetus-specific prediction intervals. Prediction intervals constitute an easy-to-interpret measure of prediction accuracy and allow identification of fetuses subject to high prediction uncertainty. Using a data set of 8712 deliveries at the Perinatal Centre at the University Clinic Erlangen (Germany), we analyzed variants of CLTMs and compared them to standard linear regression estimation techniques used in the past and to quantile regression approaches. The best-performing CLTM variant was competitive with quantile regression and linear regression approaches in terms of conditional coverage and average length of the prediction intervals. We propose that CLTMs be used because they are able to account for possible heteroscedasticity, kurtosis, and skewness of the distribution of BWs.

Relationship between parity and brachial plexus injuries

OBJECTIVE

Few characteristics have been identified as risk factors for brachial plexus injuries. We sought to investigate a potential relationship with multiparity based on clinical observation at our institution.

STUDY DESIGN

In this retrospective case series, we analyzed all brachial plexus injuries recognized at or after delivery between October 2003 and March 2013 (n=78) at a single academic medical institution. Patient, infant, labor and delivery characteristics were compared for women with and without prior vaginal deliveries.

RESULT

Of the 78 injuries, 71 (91%) occurred after a vaginal delivery and 7 (9%) after a cesarean delivery. Of the 71 injuries after a vaginal delivery, 58% occurred in women with a prior vaginal delivery (n=41, 5.7 per 10 000 live births) compared with 42% without a prior vaginal delivery (n=30, 4.0 per 10 000 live births). Multiparous patients had shorter labor courses and fewer labor interventions than nulliparous patients. Providers clinically underestimated the birth weights to a greater extent in multiparas than in nulliparas (median underestimation 590 vs 139 g, P=0.0016). The median birth weight was 4060 g in the multiparous group, which was significantly larger than affected infants born to the nulliparous group (3591 g, P=0.006). The affected infants of the multiparous group were, as expected, significantly larger than their previously born siblings (median 567 g larger, P<0.001).

CONCLUSION

Brachial plexus injuries occurred as frequently in multiparous patients as in nulliparous patients. In general, multiparous patients are more likely to have larger infants; however, providers significantly underestimate the birth weight of their infants. The findings of this study should deter providers from assuming that a prior vaginal delivery is protective against brachial plexus injuries.

Bariatric Surgery in Women: A Boon Needs Special Care During Pregnancy

Obesity is one of the leading causes of health related disorder and has reached epidemic proportions not only in developed nations but also in developing countries like India. Bariatric surgery has become a popular alternative for obese women planning pregnancy. A multidisciplinary approach involving the obstetrician, the bariatric surgeon and the nutritionist is required to manage pregnancy following bariatric surgery. Early consultation should be done to determine baseline nutritional status and the importance of regular check-ups must be explained. Nutritional supplementation should be tailored to the patient's status and the type of bariatric surgery performed.

[Epidemiology of shoulder dystocia]

OBJECTIVES

To synthetize the available evidence regarding the incidence and risk factors of shoulder dystocia (SD).

METHODS

Consultation of the Medline database, and of national guidelines.

RESULTS

Shoulder dystocia is defined as a vaginal delivery that requires additional obstetric manoeuvres to deliver the foetus after the head has delivered and gentle traction has failed. With this definition, the incidence of SD in population-based studies is about 0.5-1% of vaginal deliveries. Many risk factors have been described but most associations are not independent, or have not been constantly found. The 2 characteristics consistently found as independent risk factors for SD in the literature are previous SD (incidence of SD of about 10% in parturients with previous SD) and foetal macrosomia. Maternal diabetes and obesity also are associated with a higher risk of SD (2 to 4 folds) but these associations may be completely explained by foetal macrosomia. However, even factors independently and constantly associated with SD do not allow a valid prediction of SD because they are not discriminant; 50 to 70% of SD cases occur in their absence, and the great majority of deliveries when they are present is not associated with SD.

CONCLUSION

Shoulder dystocia is defined by the need for additional obstetric manoeuvres to deliver the foetus after the head has delivered and gentle traction has failed, and complicates 0.5-1% of vaginal deliveries. Its main risk factors are previous SD and macrosomia, but they are poorly predictive. SD remains a non-predictable obstetrics emergency. Knowledge of SD risk factors should increase the vigilance of clinicians in at-risk contexts.

Prevention of shoulder dystocia related birth injuries: Myths and facts

Traditionally, brachial plexus damage was attributed to excessive traction applied on the fetal head at delivery. Recently, it was proposed that most injuries occur spontaneously in utero. The author has studied the mechanism of neurological birth injuries based on 338 actual cases with special attention to (1) fetal macrosomia; (2) maternal diabetes; and (3) methods of delivery. There was a high coincidence between use of traction and brachial plexus injuries. Instrumental extractions increased the risk exponentially. Erb’s palsy following cesarean section was exceedingly rare. These facts imply that spontaneous neurological injury in utero is extremely rare phenomenon. Literary reports show that shoulder dystocia and its associated injuries increased in the United States several-fold since the introduction of active management of delivery in the 1970’s. Such a dramatic change in a stable population is unlikely to be caused by incidental spontaneous events unrelated to external factors. The cited investigations indicate that brachial plexus damage typically is traction related. The traditional technique which precludes traction is the optimal method for avoiding arrest of the shoulders and its associated neurological birth injuries. Effective prevention also requires meticulous prenatal care and elective abdominal delivery of macrosomic fetuses in carefully selected cases.

Diabetes in pregnancy: timing and mode of delivery

Diabetes in pregnancy represents a risk condition for adverse maternal and feto-neonatal outcomes and many of these complications might occur during labor and delivery. In this context, the obstetrician managing women with pre-existing and gestational diabetes should consider (1) how these conditions might affect labor and delivery outcomes; (2) what are the current recommendations on management; and (3) which other factors should be considered to decide about the timing and mode of delivery. The analysis of the studies considered in this review leads to the conclusion that the decision to deliver should be primarily intended to reduce the risk of stillbirth, macrosomia, and shoulder dystocia. In this context, this review provides useful information for managing specific subgroups of diabetic women that may present overlapping risk factors, such as women with insulin-requiring diabetes and/or obesity and/or prenatal suspicion of macrosomic fetus. To date, the lack of definitive evidences and the complexity of the problem suggest that the "appropriate" clinical management should be customized according with the clinical condition, the type and mode of intervention, its consequences on outcomes, and considering the woman's consent and informed decisions.

Shoulder dystocia: definitions and incidence

Though subjective in nature, both the American College of Obstetricians and Gynecologists practice bulletin and the Royal College of Obstetricians and Gynaecologists green guideline are in agreement on the descriptor of shoulder dystocia: requirement of additional obstetric maneuvers when gentle downward traction has failed to affect the delivery of the shoulders. The rate of shoulder dystocia is about 1.4% of all deliveries and 0.7% for vaginal births. Compared to non-diabetics (0.6%), among diabetics, the rate of impacted shoulders is 201% higher (1.9%); newborns delivered by vacuum or forceps have 254% higher likelihood of shoulder dystocia than those born spontaneously (2.0% vs. 0.6%, respectively). When the birthweight is categorized as <4000, 4000-4449, and >4500 g, the likelihood of shoulder dystocia in the US vs. other countries varies significantly. Future studies should focus on lowering the rate of shoulder dystocia and its associated morbidities, without concomitantly increasing the rate of cesarean delivery.

Neonatal brachial plexus palsy: incidence, prevalence, and temporal trends

Epidemiological knowledge of the incidence, prevalence, and temporal changes of neonatal brachial plexuses palsy (NBPP) should assist the clinician, avert unnecessary interventions, and help formulate evidence-based health policies. A summary of 63 publications in the English language with over 17 million births and 24,000 NBPPs is notable for six things. First, the rate of NBPP in the US and other countries is comparable: 1.5 vs. 1.3 per 1000 total births, respectively. Second, the rate of NBPP may be decreasing: 0.9, 1.0 and 0.5 per 1,000 births for publications before 1990, 1990-2000, and after 2000, respectively. Third, the likelihood of not having concomitant shoulder dystocia with NBPP was 76% overall, though it varied by whether the publication was from the US (78%) vs. other countries (47%). Fourth, the likelihood of NBPP being permanent (lasting at least 12 months) was 10-18% in the US-based reports and 19-23% in other countries. Fifth, in studies from the US, the rate of permanent NBPP is 1.1-2.2 per 10,000 births and 2.9-3.7 per 10,000 births in other nations. Sixth, we estimate that approximately 5000 NBPPs occur every year in the US, of which over 580-1050 are permanent, and that since birth, 63,000 adults have been afflicted with persistent paresis of their brachial plexus. The exceedingly infrequent nature of permanent NBPP necessitates a multi-center study to improve our understanding of the antecedent factors and to abate the long-term sequela.

Identification of pregnancies at increased risk of brachial plexus birth palsy - the construction of a weighted risk score

OBJECTIVE

Since it is difficult to identify women at increased risk of fetal brachial plexus birth palsy (BPBP) during labor and delivery, we aimed to construct and validate a risk score.

METHODS

A retrospective case-control study was undertaken in 2001 and 2006 in an urban context in Malmö, Sweden. A risk score was constructed for all women who had received routine municipal maternal health care at Skåne University Hospital (n = 10 459). The model was validated among all pregnant women with BPBP and controls in Sweden between 2006 and 2007.

RESULTS

The likelihood of BPBP increased as the risk score rose: 3.1% of the women studied had a risk score ≥5, including 32.1% of the BPBP cases, where the risk showed a 38-fold increase, as compared to those with a risk score ≤1 (2/3 of the population).

CONCLUSION

Our findings indicate that it is possible to identify women at increased risk of having a child with BPBP by using variables observable in advance of delivery.

Impact of maternal obesity on fetal health

The obesity epidemic is a problem of global importance with a profound impact on maternal-fetal health. Maternal overweight and obesity causes pregnancy complications such as gestational diabetes, hypertension and preeclampsia and affects fetal growth. Maternal obesity offers an altered genetic, hormonal and biochemical environment for the developing fetus/embryo and influences fetal growth and organ development. Offspring of obese mothers are subject to an increased risk of fetal demise, congenital anomalies and disrupted growth patterns, causing an increase in perinatal mortality. The impact of maternal obesity extends beyond intrauterine and neonatal life to childhood, adolescence and adulthood.

Prospective validation of fetal weight estimation using fractional limb volume

OBJECTIVES

To prospectively validate the use of fractional limb volume measurements for estimated fetal weight (EFW) during the second and third trimesters of pregnancy and to summarize the medical literature regarding application of fractional limb volume for fetal weight estimation.

METHODS

One hundred and sixty-four women prospectively underwent three-dimensional ultrasonography within 4 days of delivery. Birth weights (BWs) ranged from 390 to 5426 g. Fetal measurements were extracted using volume datasets for biparietal diameter, abdominal circumference, femur diaphysis length, fractional arm volume and fractional thigh volume. Fractional limb volumes were manually traced from a central portion of the humerus or femur diaphysis. Mean percentage differences and SDs of the percentage differences were calculated for EFW. The proportion of newborns with EFW within 5 or 10% of BW were compared with an estimate obtained using a Hadlock formula that was modified using model coefficients from the same local population sample.

RESULTS

Ultrasound scans were performed between 21.7 and 42 weeks' menstrual age. Optimal model performance (1.9 ± 6.6%) resulted from using a combination of biparietal diameter, abdominal circumference and fractional thigh volume. The precision of this model was superior to results obtained using a modified Hadlock model (1.1 ± 8.4%), although accuracy of these predictions was slightly decreased for female infants. For all fetuses, the prediction model that incorporated fractional thigh volume correctly classified a greater proportion of EFW within 5% (55.1 vs 43.7%; P = 0.03) or 10% (86.5 vs 75.9%; P < 0.05) of BW when compared with the modified Hadlock model.

CONCLUSIONS

Fractional thigh volume can be added to two-dimensional sonographic measurements of the head and trunk to improve the precision of fetal weight estimation. This approach permits the inclusion of soft tissue development as part of a weight estimation procedure for the assessment of generalized fetal nutritional status.

Fetal macrosomia and shoulder dystocia in women with gestational diabetes: risks amenable to treatment?

Fetal macrosomia and maternal diabetes are independent risk factors for shoulder dystocia, an obstetrical emergency that may cause permanent neonatal injury. Randomized trials of glycemic control in pregnancies complicated by gestational diabetes reveal decreased rates of macrosomia and shoulder dystocia among those treated. However, definitions of gestational diabetes vary and a specific glycemic threshold for clinically significant risk reduction remains to be delineated. This review discusses risks associated with gestational diabetes including macrosomia (birth weight above 4000-4500 g) and delivery-related morbidity, specifically, shoulder dystocia. Subsequently, we will review recent randomized trials assessing the impact of glycemic control on these delivery-related morbidities. Finally, we will examine a large observational study that found associations with delivery-related morbidity and hyperglycemia below current diabetic thresholds, observations which may suggest reexamination of current diagnosis guidelines for gestational diabetes.

Use of birth weight threshold for macrosomia to identify fetuses at risk of shoulder dystocia among Chinese populations

OBJECTIVE

To assess the incidence of macrosomia and the influence of birth weight on shoulder dystocia risk among a cohort of Chinese women.

METHODS

A retrospective analysis was conducted of 80953 singleton deliveries recorded at the Prince of Wales Hospital, Hong Kong, between 1995 and 2009. The incidences of macrosomia (birth weight ≥ 4000 g) and shoulder dystocia were assessed by birth weight; risk factors for shoulder dystocia were examined by multiple logistic regression analysis.

RESULTS

The incidence of macrosomia was 3.4%. The overall incidence of shoulder dystocia was 0.3%; however, the incidence rose with increasing birth weight. The odds ratio (OR) for a birth weight of 4000-4199 g was 22.40, while the OR for a birth weight of 4200 g or above was 76.10. Other independent risk factors for shoulder dystocia included instrumental delivery (OR 12.11), short stature (OR 2.16), maternal diabetes mellitus (OR 1.78), and obesity (OR 1.58).

CONCLUSION

Although the overall incidences of macrosomia and shoulder dystocia were low, the risk of shoulder dystocia was strongly linked to increasing birth weight. International guidelines for elective cesarean delivery in suspected cases of macrosomia may not, therefore, apply to Chinese women.

Gestational diabetes mellitus

Gestational diabetes mellitus (GDM) represents a heterogeneous group of metabolic disorders, which result in varying degrees of maternal hyperglycemia and pregnancy-associated risk. The frequency of GDM is rising globally and may also increase further as less-stringent criteria for the diagnosis are potentially adopted. The additional burden placed on the health care system by increasing cases of GDM requires consideration of diagnostic approaches and currently used treatment strategies. Debate continues to surround both the diagnosis and treatment of GDM despite several recent large-scale studies addressing these controversial issues. As many now have come to reassess their approach to the management of GDM, we provide information in this review to help guide this process. The goal for each health care practitioner should continue to be to provide optimum care for women discovered to have carbohydrate intolerance during pregnancy.

Characteristics and outcome of brachial plexus birth palsy in neonates

AIM

To relate pregnancy characteristics to extent and reversibility of brachial plexus birth palsy (BPBP) in neonates.

METHODS

Retrospective case-control study: newborns with a registered diagnosis of BPBP (n = 168) 1990-2005 were compared to data from a randomly selected control group (n = 1000). Characteristics were related to the level of injury, reversibility and outcome.

RESULTS

Among 51,841 newborns, 168 cases with BPBP were found (incidence 3.2/1000 newborns/year). Extent and reversibility of lesion did not differ with respect to characteristics of mothers, foetuses or deliveries. Children with C5-C6 and C5-C6-C7 injuries had complete recovery in 86% and 38%, respectively. Global injuries (C5-Th1) always had permanent disability. Accelerators (foetal weight gain >35 g/day after 32 weeks of gestation) and foetuses with estimated weight deviation ≥ +22% at 32 weeks were at seven- and ninefold increased risk of BPBP. Parous women were at doubled risk as compared to nulliparous women.

CONCLUSION

Maternal and foetal characteristics influence risk of BPBP, but not the extent of injury or reversibility of injury. Because of the high risk of permanent disability and modest risk of low Apgar or pH among newborns with BPBP, the recommendation of prompt delivery may need to be re-evaluated.

Are the neonatal outcomes similar in large-for-gestational age infants delivered by women with or without gestational diabetes mellitus?

BACKGROUND

Infants are considered large for gestational age (LGA) if their birth weight is greater than the 90th percentile for gestational age and they have an increased risk for adverse perinatal outcomes. Maternal diabetes is one of the factors affecting birthweight. However there are limited data on the perinatal outcomes of infants of gestational diabetic mothers. The aim of the present study was to compare the neonatal outcomes of LGA infants delivered by women with and without gestational diabetes mellitus.

METHODS

This was a retrospective study of LGA infants of ≥36 weeks of gestation born at the Gazi University Medical School Hospital during the period of 2006-2009. Neonatal outcomes included hypoglycemia and polycythemia in the early neonatal period and hospital admissions. The Chi-square and Student's t test were used for comparing variables.

RESULTS

Seven hundred eligible infant-mother pairs were enrolled in the study. Eighty-seven of them (12.4%) were infants of gestational diabetic mothers and 613 (87.6%) were infants of non-diabetic mothers. The incidence of hypoglycemia at the first hour was higher in infants of diabetic mothers (12.8%) than in infants of non-diabetic mothers (5.3%) (P=0.014). Polycythemia was also more frequently observed in infants of the gestational diabetic mothers (9.3%) than in infants of the non-diabetic mothers (3.0%) (P=0.010). Although overall hospital admission rates were not different between the two groups, infants of diabetic mothers were more likely to be admitted because of resistant hypoglycemia (P=0.045).

CONCLUSIONS

The results of this study suggested that LGA infants of mothers with gestational diabetes mellitus were at a greater risk for hypoglycemia and polycythemia in the early neonatal period than LGA infants of nondiabetic mothers.

Impending macrosomia: will induction of labour modify the risk of caesarean delivery?

OBJECTIVE

To compare the annual incidence rates of caesarean delivery between induction of labour and expectant management in the setting of macrosomia.

DESIGN

This is a retrospective cohort study.

SETTING

Deliveries in the USA in 2003.

POPULATION

Singleton births of macrosomic neonates to low-risk nulliparous women at 39 weeks of gestation and beyond.

METHODS

Women who had induction of labour at 39 weeks of gestation with a neonatal birthweight of 4000 ± 125 g (3875-4125 g) were compared with women who delivered (either induced or spontaneous labour) at 40, 41 or 42 weeks (i.e. expectant management), assuming an intrauterine fetal weight gain of 200 g per additional week of gestation. Similar comparisons were made at 40 and 41 weeks of gestation. Chi-square test and multivariable logistic regression analysis were used for statistical comparison.

MAIN OUTCOME MEASURES

Method of delivery, 5-minute Apgar scores, neonatal injury.

RESULTS

There were 132,112 women meeting the study criteria. In women whose labours were induced at 39 weeks and who delivered a neonate with a birthweight of 4000 ± 125 g, the frequency of caesarean was lower compared with women who delivered at a later gestational age (35.2% versus 40.9%; adjusted OR 1.25, 95% CI 1.17-1.33). This trend was maintained at both 40 weeks (36.1% versus 42.6%; adjusted OR 1.31, 95% CI 1.23-1.40) and 41 weeks (38.9% versus 41.8%; adjusted OR 1.16, 95% CI 1.06-1.28) of gestation.

CONCLUSIONS

In the setting of known birthweight, it appears that induction of labour may reduce the risk of caesarean delivery. Future research should concentrate on clinical and radiological methods to better estimate birthweight to facilitate improved clinical care. These findings deserve examination in a large, prospective, randomised trial.

The legacy of nanotechnology: revolution and prospects in neurosurgery

Nanotechnology has been an ever-growing field since the discovery of carbon fullerenes, and is being assimilated progressively into a variety of other disciplines including medical science. The association with neurosurgery had initially been less well characterized compared to other organ systems, but has recently offered promising future potential for a wide range of utilities including new therapeutic options for Glioblastoma Multiforme, neurprotection against oxidative stress, nerve nanorepair, nanodiagnosis of Alzheimer's disease, nanoimaging with nanoparticles and quantum dots, nanomanipulation of CNS with surgical nanobots, and nanoneuromodulation with nanofibres & nanowires. This article examines such potentials as well as others, of the utility of nanotechnology in Neurosurgery.

Birth fracture of the clavicle

Birth fracture of the clavicle occurs in approximately 0.4% to 10% of vaginal births. The most common symptom is decreased movement of the ipsilateral arm. A high index of suspicion is necessary in infants presenting without any symptoms. Although displaced clavicular fractures are relatively easily diagnosed clinically, nondisplaced fractures may be apparent only after callus formation, or if all neonates are subjected to radiography or ultrasonography, or multiple physical examinations by trained examiners. We present a case of an infant delivered with vaginal labor with a fracture of the right clavicle diagnosed after apparent callus formation and discuss the current evidence of associated factors and obstetrical care.

Perinatal brachial plexus palsy

BACKGROUND

Perinatal brachial plexus palsy (PBPP) is a flaccid paralysis of the arm at birth that affects different nerves of the brachial plexus supplied by C5 to T1 in 0.42 to 5.1 infants per 1000 live births.

OBJECTIVES

To identify antenatal factors associated with PBPP and possible preventive measures, and to review the natural history as compared with the outcome after primary or secondary surgical interventions.

METHODS

A literature search on randomized controlled trials, systematic reviews and meta-analyses on the prevention and treatment of PBPP was performed. EMBASE, Medline, CINAHL and the Cochrane Library were searched until June 2005. Key words for searches included 'brachial plexus', 'brachial plexus neuropathy', 'brachial plexus injury', 'birth injury' and 'paralysis, obstetric'.

RESULTS

There were no prospective studies on the cause or prevention of PBPP. Whereas birth trauma is said to be the most common cause, there is some evidence that PBPP may occur before delivery. Shoulder dystocia and PBPP are largely unpredictable, although associations of PBPP with shoulder dystocia, infants who are large for gestational age, maternal diabetes and instrumental delivery have been reported. The various forms of PBPP, clinical findings and diagnostic measures are described. Recent evidence suggests that the natural history of PBPP is not all favourable, and residual deficits are estimated at 20% to 30%, in contrast with the previous optimistic view of full recovery in greater than 90% of affected children. There were no randomized controlled trials on nonoperative management. There was no conclusive evidence that primary surgical exploration of the brachial plexus supercedes conservative management for improved outcome. However, results from nonrandomized studies indicated that children with severe injuries do better with surgical repair. Secondary surgical reconstructions were inferior to primary intervention, but could still improve arm function in children with serious impairments.

CONCLUSIONS

It is not possible to predict which infants are at risk for PBPP, and therefore amenable to preventive measures. Twenty-five per cent of affected infants will experience permanent impairment and injury. If recovery is incomplete by the end of the first month, referral to a multidisciplinary team is necessary. Further research into prediction, prevention and best mode of treatment needs to be done.

Shoulder Dystocia: Etiology, Common Risk Factors, and Management

Shoulder dystocia and brachial plexus injury occur in 0.5% to 1.5% of all births. Risk factors for both include maternal obesity, excessive prenatal weight gain, maternal diabetes, protracted labor, and fetal macrosomia. These factors are involved in only about 50% of births complicated by shoulder dystocia or brachial plexus injury. Shoulder dystocia has a low recurrence rate (9.8%-16.7%), although history of previous shoulder dystocia is the most reliable predictor of occurrence. Brachial plexus injury is the most common morbidity associated with shoulder dystocia, but 50% of newborns who present with this injury were not subject to shoulder dystocia at birth. Most brachial plexus injuries are transient, although 5% to 22% become permanent. Shoulder dystocia followed by permanent brachial plexus injury or mental impairment is one of the leading causes of malpractice allegations. Prompt assessment and management of shoulder dystocia and preparation to maximize the efficiency of shoulder dystocia maneuvers are critical. Documentation of the appropriate use of maneuvers to relieve shoulder dystocia demonstrates standard of care practice, thereby decreasing the potential for successful malpractice allegations.

The influence of maternal glycaemia and dietary glycaemic index on pregnancy outcome in healthy mothers

Infant birth weight has increased in Ireland in recent years along with levels of childhood overweight and obesity. The present article reviews the current literature on maternal glycaemia and the role of the dietary glycaemic index (GI) and its impact on pregnancy outcomes. It is known that maternal weight and weight gain significantly influence infant birth weight. Fetal macrosomia (birth weight >4000 g) is associated with an increased risk of perinatal trauma to both mother and infant. Furthermore, macrosomic infants have greater risk of being obese in childhood, adolescence and adulthood compared to normal-sized infants. There is evidence that there is a direct relationship between maternal blood glucose levels during pregnancy and fetal growth and size at birth, even when maternal blood glucose levels are within their normal range. Thus, maintaining blood glucose concentrations within normal parameters during pregnancy may reduce the incidence of fetal macrosomia. Maternal diet, and particularly its carbohydrate (CHO) type and content, influences maternal blood glucose concentrations. However, different CHO foods produce different glycaemic responses. The GI was conceived by Jenkins in 1981 as a method for assessing the glycaemic responses of different CHO. Data from clinical studies in healthy pregnant women have documented that consuming a low-GI diet during pregnancy reduces peaks in postprandial glucose levels and normalises infant birth weight. Pregnancy is a physiological condition where the GI may be of particular relevance as glucose is the primary fuel for fetal growth.

Retinol-binding protein 4: a novel adipokine implicated in the genesis of LGA in the absence of gestational diabetes mellitus

OBJECTIVE

Adipokines (cytokines produced by adipose tissue) play a major role in the control of body weight and energy distribution. Retinol-binding protein 4 (RBP4), only recently recognized as an adipokine, has been proposed to modulate systemic insulin sensitivity. The goal of this study was to determine whether there is an association between maternal plasma RBP4 concentration and the birth of a large-for-gestational-age (LGA) newborn in women with and without gestational diabetes mellitus (GDM).

STUDY DESIGN

This cross-sectional study included pregnant women at term in the following groups: 1) normal pregnancy with an appropriate-for-gestational-age (AGA) neonate (n=64); 2) normal pregnancy with an LGA neonate (n=44); 3) GDM with an AGA neonate (n=55); and 4) GDM with an LGA neonate (n=42). Maternal plasma RBP4 concentration was determined by ELISA. Parametric and non-parametric statistics were used for analyses.

RESULTS

1) Patients with GDM, either with AGA or LGA neonates, had a higher median plasma concentration of RBP4 than normal pregnant women who delivered an AGA neonate (P=0.01 and P=0.008, respectively); 2) mothers without GDM but with LGA neonates had a higher median plasma concentration of RBP4 than those with normal pregnancy and AGA newborns (P=0.001); 3) these findings remained significant after adjusting for maternal age, body mass index and gestational age at blood sampling.

CONCLUSION

GDM is characterized by alterations in maternal circulating RBP4 concentrations akin to those of Type 2 diabetes mellitus. RBP4 concentrations in maternal plasma may play a role in accelerated fetal growth in the absence of overt carbohydrate intolerance.