Macrosomic births in the united states: determinants, outcomes, and proposed grades of risk

Tamanho ao nascer e problemas de saúde mental aos 11 anos em uma coorte brasileira de nascimentos

O objetivo foi avaliar a associação entre tamanho ao nascer e problemas de saúde mental aos 11 anos na Coorte de Nascimentos de Pelotas, Rio Grande do Sul, Brasil, de 1993. Foram pesados e medidos ao nascer 4.358 recém-nascidos. Avaliou-se problemas de saúde mental com o questionário de capacidades e dificuldades (Strengths and Difficulties Questionnaire - SDQ). A prevalência de problemas de saúde mental foi de 32% (IC95%: 31-33). Na análise ajustada, os 291 (6,7%) recém-nascidos com escorez de peso/idade e os 268 (6,2%) com índice de massa corporal (IMC)/idade < -2 DP tiveram, respectivamente, 27% (IC95%: 7-49) e 29% (IC95%: 10-51) maior risco de apresentar problemas de saúde mental aos 11 anos quando comparados com aqueles com escore normal. Os 102 (2,43%) recém-nascidos com escorez de IMC e os 279 (6,4%) com perímetro cefálico/idade > +2 DP tiveram, respectivamente, 34% (IC95%: 6-71) e 19% (IC95%: 1-40) maior risco de apresentar esses problemas se comparados com aqueles com escore normal. Os resultados sugerem que fatores ocorridos na gestação e refletidos nas medidas de tamanho ao nascer podem ocasionar problemas de saúde mental em etapas tardias.

A customized standard of large size for gestational age to predict intrapartum morbidity

OBJECTIVE

The purpose of this study was to determine whether a customized standard of large-for-gestational age (LGA) identifies pregnancies with increased perinatal risk.

STUDY DESIGN

We evaluated 7510 estimates of fetal weight to generate a fetal growth curve. Next, we analyzed the gestational age at delivery, physiologic and pathological variables from 5072 pregnancies to predict birthweight, and calculated a customized ideal birthweight and cutoff for LGA. In a separate analysis of 32,271 pregnancies, rates of macrosomia-related adverse outcomes were compared in pregnancies that had been identified as LGA by a customized standard (LGA(cust)) and those pregnancies that had been identified as LGA or macrosomic by conventional standards.

RESULTS

LGA(cust) pregnancies carried increased risk of shoulder dystocia, third- or fourth-degree laceration, and cephalopelvic disproportion. LGA(cust) pregnancies that did not meet conventional criteria for LGA/macrosomia were at increased risk of all measured outcomes.

CONCLUSION

A customized standard of LGA identifies a previously unrecognized population that is at increased risk of perinatal morbidity.

Variation in Excessive Fetal Growth across Levels of Prenatal Care among Women with Gestational Diabetes

OBJECTIVE

Examine the association between prenatal care and excessive fetal growth outcomes among mothers with gestational diabetes mellitus (GDM).

METHODS

We conducted a retrospective analysis of 2004-2007 singleton live births to South Carolina women, limited to those for whom both birth certificate and hospital discharge data were available (N = 179 957). Gestational diabetes mellitus was identified from birth certificate and/or hospital discharge claims. Measures of excessive fetal growth were large for gestational age (90th and 95th percentiles) and macrosomia (birth weight > 4500 g). The Adequacy of Prenatal Care Utilization index was used to measure prenatal care.

RESULTS

Gestational diabetes mellitus was recorded for 6.9% of women in the study population. Women with GDM were more likely than other women to have an infant with excessive fetal growth, regardless of the level of prenatal care; however, there was a significant interaction between GDM status and levels of prenatal care. All women with GDM had increased odds for large infant outcomes. However, those receiving inadequate prenatal care were markedly more likely to experience excessive fetal growth outcomes (odds ratio = 1.38, confidence interval = 1.15-1.66) than women also with GDM and intermediate/adequate prenatal care. Similar patterns were noted for large for gestational age (95th) and macrosomia (total birth weight ≥ 4500 g).

CONCLUSIONS

Observed associations suggest a link between inadequate prenatal care and a higher risk for excessive fetal growth among women with GDM. Further research is needed to clarify the nature of the association and suggest ways to get high-risk women into care sooner.

Maternal outcome of gestational diabetes mellitus

OBJECTIVE

To estimate maternal outcome of treated or untreated gestational diabetes mellitus (GDM).

METHODS

French and English publications were searched using PubMed and the Cochrane library.

RESULTS

The diagnosis of GDM includes a high risk population for preeclampsia and Caesarean sections (EL3). The risks are positively correlated with the level of hyperglycaemia in a linear way (EL2). Intensive treatment of mild GDM compared with routine care reduces the risk of pregnancy-induced hypertension (preeclampsia, gestational hypertension). Moreover, it does not increase the risk of operative vaginal delivery, Caesarean section and postpartum haemorrhage (EL1). Being overweight, obesity and maternal hyperglycaemia are independent risk factors for preeclampsia (EL2). Their association with GDM increases the risk of preeclampsia and Caesarean section compared to diabetic women with a normal body mass index (EL3). The association of several risk factors (such as advanced maternal age, pre-existing chronic hypertension, pre-existing nephropathy, obesity, suboptimal glycaemic control) increases the risk of preeclampsia. In that case, the classic follow-up (blood pressure measurement, proteinuria) should be more frequent than monthly (professional consensus). The risk of Caesarean section is increased by macrosomia, whether suspected prenatally or not, but this increased risk remains whatever the birth weight (EL3). Diagnosis and treatment of GDM do not reduce the risk of severe perineal lesions, operative vaginal delivery and postpartum haemorrhage (EL2). Some psychological symptoms, such as anxiety and alteration of self-perception, can occur upon diagnosis of GDM (EL3). The treatment of GDM appears to reduce the risk of postpartum depression symptoms (EL2).

CONCLUSION

Most of the information published on GDM covers the risks of preeclampsia and Caesarean section; intensive care of GDM reduces these risks. Pregnancy care should be adjusted to the risk factors.

Inherited destiny? Genetics and gestational diabetes mellitus

Despite years of investigation, very little is known about the genetic predisposition for gestational diabetes mellitus (GDM). However, the advent of genome-wide association and identification of loci contributing to susceptibility to type 2 diabetes mellitus has opened a small window into the genetics of GDM. More importantly, the study of the genetics of GDM has not only illuminated potential new biology underlying diabetes in pregnancy, but has also provided insights into fetal outcomes. Here, I review some of the insights into GDM and fetal outcomes gained through the study of both rare and common genetic variation. I also discuss whether recent testing of type 2 diabetes mellitus susceptibility loci in GDM case-control samples changes views of whether GDM is a distinct form of diabetes. Finally, I examine how the study of susceptibility loci can be used to influence clinical care, one of the great promises of the new era of human genome analysis.

Assessment of Canadian Cree infants' birth size using the WHO Child Growth Standards

OBJECTIVES

The WHO Child Growth Standards (CGS) which were recently adopted by the Canadian Pediatric Society were used to assess the relative size of Cree newborns.

METHODS

Birth weight, length, and head circumference, and growth indices of 2,127 Cree newborns were compared with the CGS. Maternal characteristics of pregnancy and infant birth outcomes were recorded and stratified by birth weight category.

RESULTS

Among Cree newborns, 2.4% were low birth weight (LBW) (<2,500 g) and 36.5% were high birth weight (≥4,000 g). The median birth weight (g) for Cree male (4,030) and female (3,900) term newborns was higher than for male (3,346) and female (3,232) newborns of the CGS. Fewer than 1.5% of Cree infants had z-scores <-2SD from the WHO CGS median for BMI-for-age, length-for-age, weight-for-age, or head circumference-for-age whereas 4.6, 7.8, and 23.4% percent had z-scores >+2SD from the WHO CGS median for weight-for-length-for-age, BMI-for-age and head circumference-for-age, respectively. The majority (53.4%) of pregnancies was complicated by obesity and 10.3% were complicated by gestational diabetes mellitus (GDM). Infants weighing 4,000-4,499 g had a comparable prevalence of operative delivery (15.4%) as infants weighing 2,500-3,999 g (13.7%). Infants weighing ≥4,500 g had the highest prevalence of birth injuries (14.0%) and being born to women whose pregnancies were complicated by GDM (20%).

CONCLUSIONS

Cree newborns were larger than newborns of the CGS. The appropriateness for Cree infants of defining low and high birth weight from the WHO CGS is uncertain and may lead to inaccurate prognosis of postnatal health.

Developmental considerations in working with newborn infants of mothers with diabetes

Infants of diabetic mothers (IDMs) are at risk for an altered developmental course beginning with physiologic alterations in utero. This article describes physiologic and behavioral factors that impact the fetus and newborn infant and may have long-term developmental consequences. A clinical reasoning process to support development optimizes the outcomes of IDMs while in the NICU. Specific interventions are suggested.

Cost-effectiveness of elective induction of labor at 41 weeks in nulliparous women

OBJECTIVE

To investigate the cost-effectiveness of elective induction of labor at 41 weeks in nulliparous women.

STUDY DESIGN

A decision analytic model comparing induction of labor at 41 weeks vs expectant management with antenatal testing until 42 weeks in nulliparas was designed. Baseline assumptions were derived from the literature as well as from analysis of the National Birth Cohort dataset and included an intrauterine fetal demise rate of 0.12% in the 41st week and a cesarean rate of 27% in women induced at 41 weeks. One-way and multiway sensitivity analyses were conducted to examine the robustness of the findings.

RESULTS

Compared with expectant management, induction of labor is cost-effective with an incremental cost of $10,945 per quality-adjusted life year gained. Induction of labor at 41 weeks also resulted in a lower rate of adverse obstetric outcomes, including neonatal demise, shoulder dystocia, meconium aspiration syndrome, and severe perineal lacerations.

CONCLUSION

Elective induction of labor at 41 weeks is cost-effective and improves outcomes.

Diabetes revealed: multisystem danger

OBJECTIVE

The purpose of this article is to review the role of diagnostic imaging in the evaluation of women with diabetes.

CONCLUSION

Diabetic patients present a challenging population for the performance of various imaging studies and special considerations need to be made to obtain adequate studies. Imaging plays a significant role in assessing the multisystem morbidity of diabetes. Furthermore, diabetes in women may have some unique features and consequences and imaging studies can aid in the correct management of these patients.

Birth weight in type 1 diabetic pregnancy

Our aim was to investigate whether birth weight in mothers with diabetes mellitus type 1 is higher as compared to nondiabetic controls. Methods. A retrospective study was performed using an existing database covering the region of Flanders, Belgium. Data included the presence of diabetes type 1, hypertension, parity, maternal age, the use artificial reproductive technology, fetal- neonatal death, congenital anomalies, admission to a neonatal intensive care unit, and delivery by Caesarean section or vaginally. Results. In the period studied, 354 women with diabetes type 1 gave birth and were compared with 177.471 controls. Women with type 1 diabetes more often had a maternal age of over 35 years (16.7% versus 12.0%, P = .008, OR 1.46; 95% CI 1.09–1.95). They more frequently suffered hypertension in pregnancy (19.5% versus 4.7%, P < .0001, OR 4.91; 95% CI 3.73–6.44). Perinatal death was significantly higher in the diabetes mellitus group (3.05% versus 0.73%, P < .0001, OR 4.28; 95% CI 2.22–8.01). Caesarean section was performed almost 5 times as frequently in the diabetes versus the control group (OR 4.57; 95% CI 3.70–5.65). Birth weight was significantly higher in diabetic pregnant women from 33 until 38 weeks included, but those reaching 39 weeks and later were not different with control groups. Conclusion. In Belgium, diabetic pregnancy still carries a high risk for fetal and maternal complications; in general birth weight is significantly higher but for those reaching term there is no significant difference in birth weight.

First-trimester prediction of macrosomia

OBJECTIVE

To determine if combinations of maternal characteristics and measurements of parameters used in screening for aneuploidies at 11-13 weeks provide significant prediction of macrosomia.

METHOD

Maternal characteristics, fetal nuchal translucency (NT), free β-human chorionic gonadotrophin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) were recorded at 11(+0)-13(+6) weeks in 36,743 singleton pregnancies. Regression analysis was used to determine if in predicting macrosomia significant contributions are provided by maternal factors, fetal NT, free β-hCG and PAPP-A.

RESULTS

The risk for macrosomia increased with maternal weight and height and was higher in parous women with previous delivery of a macrosomic baby and in those with diabetes mellitus; the risk was lower in women of African and South Asian racial origins, in cigarette smokers and in those with chronic hypertension. In the macrosomic group compared to the unaffected group there were higher Δ-NT (0.167 vs. 0.116 mm), free β-hCG (1.010 vs. 0.964 MoM) and PAPP-A (1.103 vs. 1.003 MoM). Prediction of macrosomia provided by maternal factors was significantly improved by fetal NT, free β-hCG and PAPP-A (34.4 vs. 33.1% at a false-positive rate of 10%).

CONCLUSION

Prediction of macrosomia is provided in the first trimester of pregnancy by a combination of maternal characteristics and measurements of parameters used in screening for aneuploidies.

Risk factors and obstetric complications of large for gestational age births with adjustments for community effects: results from a new cohort study

BACKGROUND

High birth weight has serious adverse impacts on chronic health conditions and development in children. This study identifies the social determinants and obstetric complications of high birth weight adjusted for gestational age and baby gender.

METHODS

Pregnant women were recruited from three maternity hospitals in South-East Queensland in Australia during antenatal clinic visits. A questionnaire was completed by each participant to elicit information on eco-epidemiological exposures. Perinatal information was extracted from hospital birth records. A hierarchical mixture regression model was used in the analysis to account for the heterogeneity of birth weights and identify risk factors and obstetric complications of births that were large for gestational age. A generalized linear mixed model was used to adjust for (random) "community" effects.

RESULTS

Pre-pregnancy obesity (adjusted OR = 2.73, 95% CI = 1.49-5.01), previous pregnancy (adjusted OR = 2.03, 95% CI = 1.08-3.81), and married mothers (adjusted OR = 1.85, 95% CI = 1.00-3.42) were significantly associated with large for gestational age babies. Subsequent complications included the increased need for delivery by caesarean sections or instrumental procedures (adjusted OR = 1.98, 95% CI = 1.10-3.55), resuscitation (adjusted OR = 2.52, 95% CI = 1.33-4.79), and transfer to intensive/special care nursery (adjusted OR = 3.76, 95% CI = 1.89-7.49). Communities associated with a higher proportion of large for gestational age births were identified.

CONCLUSIONS

Pre pregnancy obesity is the principal modifiable risk factor for large for gestational age births. Large for gestational age is an important risk factor for the subsequent obstetric complications. The findings improve the evidence-base on which to base preventive interventions to reduce the impact of high birth weight on maternal and child health.

The fetal and maternal consequences of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a type of diabetes that presents during pregnancy and usually disappears shortly after a woman gives birth. Better recognition of the risk factors of GDM, combined with more universal screening for the disease in many countries, has led to the increased detection of GDM along with other forms of pregestational diabetes. There is growing evidence that GDM significantly increases the risk of a number of short- and long-term adverse consequences for the fetus and mother, the most significant of which is a predisposition to the development of metabolic syndrome and Type 2 diabetes. Maternal and childhood obesity as well as cardiovascular disease are also potential long-term consequences of GDM. On the other hand, there is a growing body of evidence suggesting that the risk of many of these consequences can be significantly reduced or eliminated by aggressive treatment of GDM. There remains, however, a great deal of controversy over when to begin screening for hyperglycemia in pregnancy and at what level of hyperglycemia should aggressive intervention be initiated.

Fetal macrosomia and pregnancy outcomes

BACKGROUND

Pregnancies with a macrosomic fetus comprise a subgroup of high-risk pregnancies. There is uncertainty in the clinical management and outcomes of such pregnancies.

AIM

We sought to examine clinical management and maternal and fetal outcomes in pregnancies with macrosomic infants at Royal Brisbane and Women's Hospital (RBWH).

METHODS

Data from 276 macrosomic births (weighing > or = 4500 g) and 294 controls (weighing 3250-3750 g) delivered during 2002-2004 at RBWH were collected from the hospital database. Univariate and logistic regression analyses were performed for maternal risk factors and maternal and neonatal outcomes that were associated with fetal macrosomia.

RESULTS

Macrosomia was more than two times likely in women with body mass index (BMI) of > 30 kg/m(2) (odds ratio (OR) 2.41, 95% confidence interval (CI) 1.26-4.61) and in male infant sex (OR 2.05, 95% CI 1.35-3.12), and four times more likely in gestation of > 40 weeks (OR 3.93, 95% CI 1.99-7.74). Maternal smoking reduced the risk of fetal macrosomia (OR 0.27, 95% CI 0.14-0.51). Macrosomia was associated with nearly two times higher risk of emergency caesarean section (OR 1.75, 95% CI 1.02-2.97) and maternal hospital stay of > 3 days (OR 1.66, 95% CI 1.11-2.50), and four times higher risk of shoulder dystocia (OR 4.08, 95% CI 1.62-10.29). Macrosomic infants were twice as likely to have resuscitation (OR 2.21, 95% CI 1.46-3.34) and intensive care nursery admission (OR 1.89, 95% CI 1.03-3.46).

CONCLUSION

Macrosomia was associated with an increased risk of adverse maternal and neonatal health outcomes. Optimal management strategies of macrosomic pregnancies need evaluation.

Modifiable risk factors for term large for gestational age births

To determine modifiable and nonmodifiable risk factors for term large for gestational age (T-LGA) births in Northern and Central Alberta and their public health importance, a retrospective cohort study (n = 115,198) of singleton live births (1996-2003) was conducted using maternal and newborn data from a provincial perinatal database. After adjusting for potential confounders, predictors of T-LGA births included prepregnancy weight 91 kg or greater, multiparity, and previous LGA birth. The strongest modifiable predictor was prepregnancy weight 91 kg or greater (OR = 2.52; CI 2.39, 2.65). The population-attributable risk percentage for prepregnancy weight 91 kg or greater was 10%.

Non-diabetic macrosomia: an obstetric dilemma

Fetal macrosomia represents a continuing challenge in obstetrics, as it has risk of shoulder dystocia leading to transient or permanent fetal, maternal injury and medicolegal liability. The overall incidence of macrosomia has been rising. Non-diabetic macrosomia is still an obstetric dilemma, as there is no clear consensus regarding its ante-partum prediction and management, as accurate diagnosis is only made retrospectively. The risk of shoulder dystocia rises from 1.4% for all vaginal deliveries to 9.2-24% for birth weights more than 4,500 g. Unfortunately, 50% of all cases of shoulder dystocia occur at birth weights of less than 4,000 g. Brachial plexus injury occurs in 1:1,000 births and permanent damage in 1:10,000 deliveries (12% of all) leading to litigation 1:45,000 deliveries. The prenatal diagnosis of macrosomia remains imprecise. Pre-pregnancy and ante-partum risk factors and ultrasound have poor predictive value. Induction of labour and prophylactic caesarean delivery has not been shown to alter the incidence of shoulder dystocia among nondiabetic patients. Caesarean section and induction of labour are associated with increased risk of operative morbidity and mortality with added cost implications.

A scoring system for detection of macrosomia and prediction of shoulder dystocia: A disappointment

OBJECTIVE

To develop a scoring system for the detection of a macrosomic fetus (birth weight (BW) >or= 4000 g) and predict shoulder dystocia among large for gestational age fetuses.

STUDY DESIGN

We retrospectively identified all singletons with accurate gestational age (GA) that were large for GA (abdominal circumference (AC) or estimated fetal weight (EFW) >or= 90% for GA) at >or=37 weeks with delivery within three weeks. The scoring system was: 2 points for biparietal diameter, head circumference, AC, or femur length >or=90% for GA, or if the amniotic fluid index (AFI) was >or=24 cm; for biometric parameters <90% or with AFI <24 cm, 0 points. The predictive values for detection of shoulder dystocia were calculated.

RESULTS

Of the 225 cohorts that met the inclusion criteria the rate of macrosomia was 39% and among vaginal deliveries (n = 120) shoulder dystocia occurred in 12% (15/120; 95% confidence interval (CI) 7-20%). The sensitivity of EFW >or=4500 g to identify a newborn with shoulder dystocia was 0% (95% CI 0-21%), positive predictive values 0% (95% CI 0-46%), and likelihood ratio of 0. For a macrosomia score >6, the corresponding values were 20% (4-48%), 25% (5-57%) and 2.3.

CONCLUSION

Though the scoring system can identify macrosomia, it offers no advantage over EFW. The scoring system and EFW are poor predictors of shoulder dystocia.

A review of sonographic estimate of fetal weight: Vagaries of accuracy

PURPOSE

To determine the factors that might influence the accuracy of sonographic estimated fetal weight.

STUDY DESIGN

A PubMed search (Jan 1975 to Jan 2003) of articles published in the English language was carried out and the inclusion criterion was that estimates were within 10% of birth weight. A Chi-square test for trend was used and odds ratio (OR) with 95% confidence intervals (CI) was calculated.

RESULTS

Over 28 years, 175 articles were identified but only 54 (31%) met the inclusion criterion. Overall 62% (8895/14 384) of the predictions were within 10% of the actual weight. The accuracy was significantly different in articles where <7 vs. >7 days were allowed to lapse between examination and delivery (OR 2.17, 95% CI 1.93, 2.45); where examinations were done by registered diagnostic medical sonographers (RDMS; 65%) versus physicians (59%) or residents (57%; p < 0.0001); in term vs. preterm patients (OR 1.97, 95% CI 1.67, 2.13); and in studies with >1000 vs. <1000 cohorts (OR 1.62; 95% CI 1.51, 1.74).

CONCLUSIONS

If feasible the sonographic examination should be done by RDMS and within a week of delivery.

Mode of delivery and birth outcomes of macrosomic infants

This review examines and summarises the literature regarding the mode of delivery of macrosomic infants and subsequent perinatal outcomes. A search of electronic databases was conducted and supplemented with investigation of the references cited in the original articles. Although the rates of obstetric complications differ among high birth weight infants delivered by caesarean section compared to those delivered vaginally, there is currently little evidence that perinatal mortality differs significantly by delivery method. Shoulder dystocia and birth injury occur with greater frequency among macrosomic infants, yet the relative inaccuracy of clinical and ultrasonographic estimates of birth weight among high birth weight infants indicates that a trial of labour may be warranted among non-diabetic mothers with a suspected macrosomic fetus. The majority of studies identified in this review utilised small sample sizes and observational design, thereby hindering valid assessments of the impact of delivery method on the mortality of this population. Consequently, an optimal management strategy has yet to be defined.

Recurrence of fetal macrosomia in non-diabetic pregnancies

Fetal macrosomia (birth weight >/=4,500 g) is known to increase a number of adverse maternal and perinatal outcomes. Although there is a clear association between maternal diabetes mellitus and fetal macrosomia, the majority of macrosomic infants are born to non-diabetic mothers. We wished to determine the recurrence rate of macrosomia in non-diabetic pregnancy and to see if a history of multiple prior macrosomic infants confers additional risk. A retrospective analysis of 14,461 term, singleton, infants born to non-diabetic mothers in 1997 and 1998 was performed, using a computerised hospital database. Among 14,461 term pregnancies, 529 infants (3.7%) were macrosomic, and the incidence was significantly higher in parous women (4.6%) compared with nulliparas (2.4%, p < 0.0001). Over the next 5 years, 164 of these women returned for another delivery. Women with a history of one macrosomic infant are at significantly increased risk of another macrosomic infant in a subsequent pregnancy (OR 15.8, 95% CI 11.45 - 21.91, p < 0.0001). For women with two or more macrosomic infants, the risk is even greater (OR 47.4, 95% CI 19.9 - 112.89, p < 0.0001). Macrosomia was associated with increased rates of instrumental delivery and anal sphincter injury regardless of parity, and additionally with increased rates of caesarean delivery and shoulder dystocia among nulliparas. Overall, 88% of women who laboured with a macrosomic infant achieved vaginal delivery.

Through the Looking Glass at Early-Life Exposures and Breast Cancer Risk

The global increase in the proportion of women diagnosed with breast cancer, inadequate access to screening and high cost of treatment for breast cancer argue strongly for a greater focus on preventive strategies. But at what age is it appropriate to begin targeting preventive approaches? The recognized role of perinatal nutrition in neurologic development and the relation of maternal nutritional status to birthweight and subsequent risk of hypertension, diabetes, and cardiovascular disease identify pregnancy and early childhood as potential phases for prevention. This review examines indicators of hormonal and nutritional exposures in early life and breast cancer risk through the lens of the life course paradigm integrated with maternal and child health research and methodology. Compared to women who were normal birthweight (2500-3999 g), women who weighed>or=4,000 g at birth have a 20 percent to 5-fold increased risk of premenopausal breast cancer. Women born preterm and likely to be small- or large-for-date also have an increased risk. Birth length is directly associated with risk and has a larger magnitude of effect than birthweight. Prior preeclamptics and their daughters have a lower risk of breast cancer than comparable normotensives. An association between infant feeding practices and breast cancer is unclear without improved exposure assessment and analysis. Rapid childhood and pubertal linear growth increases breast cancer risk, while greater body fat over the same periods reduces risk. Growth data thus far have not been calculated in Z-scores from reference growth curves for comparison across studies. Events and secular trends influencing birth cohorts may not be adequately addressed, thereby limiting the interpretation and implications of the findings. Research in nonhuman primates may help uncover underlying mechanisms.

The fetus of a diabetic mother: sonographic evaluation

Maternal hyperglycemia is responsible for many fetal adverse outcomes. Ultrasound examination of these pregnancies aims at an early detection of congenital malformations, assessment of fetal well-being, and fetal growth. This evaluation will influence clinical decision in determining the best time and mode of delivery. We reviewed data from the literature on accuracy, usefulness, and indications of ultrasound examinations in pregnancies complicated with diabetes mellitus, whether pregestational or gestational.

Comparison of estimated fetal weights using volume and 2-dimensional sonography and their relationship to neonatal markers of fat

OBJECTIVE

The purpose of this study was to compare the accuracy of traditional 2-dimensional sonographically estimated fetal weight (EW2D) with 3-dimensional volume-based estimated fetal weight (EW3D) and to evaluate the relationship between fetal limb volume, birth weight, and markers of neonatal adiposity.

METHODS

Fifty singleton pregnancies at 32 to 42 weeks' gestation underwent sonographic evaluation within 48 hours of delivery. We compared the accuracy of the EW2D and EW3D in the prediction of birth weight. The Ponderal index, sum of all skin fold measurements, estimated neonatal fat mass, and percent body fat were calculated. Paired t tests, simple regression analyses, a chi(2) test, and the Steiger z test were used where appropriate. P< .05 was considered significant.

RESULTS

The mean birth weight+/-SD was 3130+/-589 g at 38.8+/-2.1 weeks. The EW2D (r(2)=0.66) and EW3D (r(2)=0.76) estimates were both correlated with birth weight. The birth weight and neonatal fat mass were more highly correlated with the sonographically based thigh volume (r(2)=0.67 and 0.61) than femur length (r(2)=0.41 and 0.37). The mean percent error between EW2D and birth weight was larger (-3.3%+/-11.6%) than the mean percent error of EW3D (0.7%+/-9.2%; P= .0004).

CONCLUSIONS

Sonographically based fetal limb volumes, especially the fractional thigh volume, reflect neonatal fat mass and are better correlated with birth weight.

A community-based parish nurse intervention program for Mexican American women with gestational diabetes

OBJECTIVE

To examine the effects of a Parish Nurse Intervention Program (PNIP) on maternal health behaviors, glycemic control, and neonatal outcomes among Mexican American women with gestational diabetes.

DESIGN

A randomized controlled trial comparing care as usual (CAU) with a supplementary 1-hour education session for diabetes education reinforcement by a Parish Nurse.

SETTING

An outpatient treatment clinic for gestational diabetes within a 250-bed tertiary care, non-profit hospital with a Parish Nurse partnership.

PARTICIPANTS

One hundred Mexican American women were included in the study with randomization into Parish Nurse Intervention Program (n=49) and care as usual (n=51) groups.

MAIN OUTCOME MEASURES

The Health Promoting Lifestyle Profile II (HPLP II) and two measures of glycemic control pre- and post-intervention, as well as newborn size, and days of maternal and neonatal hospitalization.

RESULTS

Outcomes indicate significantly improved Health Promoting Lifestyle Profile II scores in the Parish Nurse Intervention Program group post-intervention compared with the Care As Usual group. No significant differences between groups regarding glycemic control, macrosomia, or days of maternal or neonatal hospitalization were found.

CONCLUSIONS

A Parish Nurse Intervention Program for pregnant women of Mexican descent with gestational diabetes is effective in leading to improved self-reported health promoting behaviors.

Percentage change in antenatal body mass index as a predictor of neonatal macrosomia

PURPOSE

We wanted to evaluate the predictive value of percentage change in antenatal maternal body mass index (BMI) as it relates to macrosomia, as well as to compare change in pregnancy BMI with existing weight gain guidelines.

METHODS

We analyzed data from 6 months of consecutive deliveries, focusing on first visit (first trimester) BMI, last visit (37 weeks or later) BMI, and fetal birth weight. Using regression and chi(2) analyses, we evaluated the relationship between change in BMI and macrosomia.

RESULTS

Of the 238 consecutive deliveries, we were able to analyze data from 186, of which 15.6% (n = 29) of the infants were macrosomic. Among macrosomic infants, 86.2% (25/29) of their mothers had a 25% or greater increase in BMI compared with 6.6% (10/157) of mothers of normal-weight infants (P <.001), for a relative risk 13.5% (95% confidence interval [CI], 7.3%-25.1%). Percentage change in BMI of 25% or greater had a sensitivity of 86.2% (95% CI, 68.3%-96.1%), a specificity of 93.6% (95% CI, 88.6%-96.9%), a positive predictive value of 71.4% (95% CI, 53.7%-85.4%), and a negative predictive value 97.4% (95% CI, 93.4%-99.3%) for macrosomia. Logistic regression adjusted for maternal age, race, parity, and gravidity showed that those women whose BMI increased 25% or greater were more than 200 times more likely (odds ratio [OR] = 219.3; 95% CI, 38.8-1,238.6; P <.001) to give birth to a macrosomic infant. Further adjusting for initial BMI strengthened the association (OR=1,062.4; 95% CI, 83.2-13,572.2; P < 001). Regardless of weight gain, when compared with Institute of Medicine weight gain recommendations, change in BMI or 25% or greater was associated with macrosomia (P <.001).

CONCLUSION

Independent of initial pregnancy BMI or absolute weight gain, an increase in maternal BMI of 25% or greater during pregnancy is highly predictive of macrosomia.

Risk factors for macrosomia in infants born to Latina women

OBJECTIVE

To assess risk factors for macrosomic infant birth among Latina women.

STUDY DESIGN

Prospective study of Latina women recruited during pregnancy from prenatal clinic at San Francisco General Hospital. Information was obtained through a structured interview and review of medical records.

RESULT

A total of 11% of women delivered macrosomic infants (birth weight >4000 g). In unadjusted analyses, significant risk factors for macrosomia included older maternal age, increasing gravidity, previous history of macrosomic birth and pre-pregnancy overweight. After adjusting for confounders using multivariate analyses, older mothers (10-year increments) had an elevated risk of macrosomia (odds ratio (OR) 2.59; 95% confidence interval (CI) 1.28 to 5.24).

CONCLUSION

Efforts to reduce macrosomia in Latina women should focus on older mothers.

Very high birth weight of offspring is associated with an increased risk of leukemia in their mothers: results of a population-based cohort study

Although the association between birth weight and childhood leukemia is well described, the relation between a child's birth weight and parental risk of leukemia is unknown. We linked data from the Jerusalem Perinatal Study to the Israel Cancer Registry to ascertain the incidence of leukemia in mothers and fathers in relation to their offspring's birth weight. Birth weight >or=4500 g in any of the offspring was associated with a >3-fold risk of leukemia in mothers, but not fathers. Potential mechanisms include shared exposures of high birth weight infants and their mothers, possibly to radiation or growth factors, or genetic pathways leading to both high birth weight and leukemia.

The Epidemiology of Childhood Leukemia with a Focus on Birth Weight and Diet

Leukemia is the most common childhood cancer and a major source of morbidity and mortality. The etiology of childhood leukemia remains largely unknown. Cytogenetic abnormalities determine disease subtypes, prognosis, clinical presentation, and course and may help in discovering etiological factors. Epidemiologic investigations of leukemia are complicated by many factors, including the rarity of the disease, necessitating careful study design. Two emerging areas of interest in leukemia etiology are birth weight and diet. High birth weight has been associated with increased risk of childhood leukemia. The biological mechanism behind this association may involve insulin-like growth factor I (IGF-I), which is associated with high birth weight. IGF-I may act by increasing the absolute number of stem cells available for transformation, stimulating the growth of cells that are already transformed, or a combination of effects. Diet has been linked with leukemia. Maternal dietary DNA topoisomerase II (DNAt2) inhibitor intake is associated with infant acute myeloid leukemia (AML) with the MLL gene translocation. Increased intake of fruits and vegetables has been associated with decreased leukemia risk and, relatedly, lack of maternal folate supplementation has been associated with increased childhood leukemia risk, possibly by causing DNA hypomethylation and increased DNA strand breaks. Methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms modify this risk.

Effectiveness of continuous glucose monitoring in pregnant women with diabetes: randomised clinical trial

OBJECTIVE

To evaluate the effectiveness of continuous glucose monitoring during pregnancy on maternal glycaemic control, infant birth weight, and risk of macrosomia in women with type 1 and type 2 diabetes.

DESIGN

Prospective, open label randomised controlled trial.

SETTING

Two secondary care multidisciplinary obstetric clinics for diabetes in the United Kingdom.

PARTICIPANTS

71 women with type 1 diabetes (n=46) or type 2 diabetes (n=25) allocated to antenatal care plus continuous glucose monitoring (n=38) or to standard antenatal care (n=33).

INTERVENTION

Continuous glucose monitoring was used as an educational tool to inform shared decision making and future therapeutic changes at intervals of 4-6 weeks during pregnancy. All other aspects of antenatal care were equal between the groups.

MAIN OUTCOME MEASURES

The primary outcome was maternal glycaemic control during the second and third trimesters from measurements of HbA(1c) levels every four weeks. Secondary outcomes were birth weight and risk of macrosomia using birthweight standard deviation scores and customised birthweight centiles. Statistical analyses were done on an intention to treat basis.

RESULTS

Women randomised to continuous glucose monitoring had lower mean HbA(1c) levels from 32 to 36 weeks' gestation compared with women randomised to standard antenatal care: 5.8% (SD 0.6) v 6.4% (SD 0.7). Compared with infants of mothers in the control arm those of mothers in the intervention arm had decreased mean birthweight standard deviation scores (0.9 v 1.6; effect size 0.7 SD, 95% confidence interval 0.0 to 1.3), decreased median customised birthweight centiles (69% v 93%), and a reduced risk of macrosomia (odds ratio 0.36, 95% confidence interval 0.13 to 0.98).

CONCLUSION

Continuous glucose monitoring during pregnancy is associated with improved glycaemic control in the third trimester, lower birth weight, and reduced risk of macrosomia.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN84461581.

Gestational diabetes in rural East Africa: a call to action

The number of cases of diabetes worldwide has increased significantly in the last decade. Characteristically, the incidence of gestational diabetes (GDM) reflects the incidence of type 2 diabetes mellitus (T2DM) in the background population, which is a warning that a rapid increase in the incidence is to be expected concomitant with the already observed increase in the incidence of T2DM. Although the majority of all deliveries worldwide take place in the so-called developing world, little is known about the prevalence of diabetes in pregnancy in rural areas of East Africa. Diabetes in pregnancy has effects on prospects for marriage, motherhood, and the role of women in East African society. Furthermore, intrauterine exposure to the metabolic environment of maternal diabetes, or GDM, is associated with increased risk of altered glucose homeostasis in the offspring, beginning in childhood and producing a higher prevalence of GDM in the next generation with all burdens and complications being associated with this disease. It is reasonable to conclude that more newborn infants each year are being exposed to the metabolic environment of diabetes during intrauterine development as a result of changing incidence and demographics of diabetes and pregnancy. We believe that programs and policies have to be established, including organization of the health system to provide care, medicines, and other tools necessary for diabetes in pregnancy management, consideration of accessibility and affordability of care, education for healthcare workers, and education of pregnant and nonpregnant women of reproductive age.

Factors influencing risk of macrosomia in women with gestational diabetes mellitus undergoing intensive diabetic care

AIMS

The aim of study was to assess the impact of intensive diabetic care, defined as target values for fasting glucose of 60-90mg/dl and 1-h postprandial glucose of below 130mg/dl, on neonatal birth weight in relation to risk indicators for fetal macrosomia in women with gestational diabetes mellitus (GDM).

METHODS

In women with (N=543) and without GDM (N=1011) age, height, weight, previous GDM, history of macrosomia, family history of type 2 diabetes, parity and weight gain during pregnancy were recorded.

RESULTS

Neonatal birth weight and frequency distribution of macrosomia and infants with small for gestational age did not differ between women with and without GDM. Neonatal birth weight was strongly associated with traditional risk predictors for GDM, such like prior macrosomia (OR 5.03; 95%CI 3.36-7.53), prior GDM (OR 2.52; 95%CI 1.37-4.64) and prepregnancy body mass index (BMI)>23kg/m(2) (OR 1.82; 95%CI 1.27-2.63).

CONCLUSIONS

Neonatal birth weight and the incidence of macrosomia were similar in comparison of pregnancies with and without GDM. In the population of Caucasian women the strongest single predictors for macrosomia were prior macrosomia, BMI>23kg/m(2) and prior GDM.

How big is too big? The perinatal consequences of fetal macrosomia

OBJECTIVE

The objective of the study was to examine the birthweight at which risks of perinatal death, neonatal morbidity, and cesarean delivery begin to rise and the causes and timing (antenatal, early or late neonatal, or postneonatal) of these risks.

STUDY DESIGN

This was a cohort study based on 1999-2001 US-linked stillbirth, live birth, and infant death records. Singletons weighing 2500 g or larger born to white non-Hispanic mothers at 37-44 weeks of gestation were selected (n = 5,983,409).

RESULTS

Infants with birthweights from 4000 to 4499 g were not at increased risk of mortality or morbidity vs those at 3500-3999 g, whereas those 4500-4999 g had significantly increased risks of stillbirth, neonatal mortality (especially because of birth asphyxia), birth injury, neonatal asphyxia, meconium aspiration, and cesarean delivery. Births at 5000 g or larger had even higher risks, including risk of sudden infant death syndrome.

CONCLUSION

Birthweight greater than 4500 g, and especially greater than 5000 g, is associated with increased risks of perinatal and infant mortality and morbidity.

Financial incentives do not always work: an example of cesarean sections in Taiwan

OBJECTIVES

To test the hypothesis that cesarean sections are less likely to be performed after equalizing the fees for vaginal births and cesarean sections.

METHODS

Population-based National Health Insurance inpatient claims in Taiwan are used. Pre-periods and post-periods are identified to investigate the impact of the policy changes. Logistic regressions are employed.

RESULTS

The cesarean section rates for the first, second and higher-order births are 29, 37.4 and 39.3%, while the primary cesarean section rates are 29, 11.8 and 12.1%, respectively. After taking into consideration the case-mix and birth order, the second and higher-order births were approximately 60% less likely to be cesarean deliveries compared to the first births and the increase in the VBAC fee had an additional negative effect on them. A fee equalization policy was not found to influence the cesarean delivery. The total cesarean section rate was primarily determined by the cesarean section rate for the first birth.

CONCLUSIONS

Cesarean section rates are greater for the higher-order births because of the practice "once a cesarean section, always a cesarean section". Against the background of a rapidly declining fertility rate, females play a more important role in the mode of delivery than ever before. As such, financial incentives designed specifically for obstetricians do not have the desired impact. Policies that are aimed at altering behavior should be designed within the social context.

Prediabetes and the big baby

The concept of prediabetes has come to the fore again with the worldwide epidemic of Type 2 diabetes. The careful observations of W. P. U. Jackson and his colleagues in Cape Town, South Africa 50 years ago still deserve attention. Maternal hyperglycaemia cannot be the only cause of fetal macrosomia, and the pathophysiological reason for the unexplained stillbirth in late diabetic pregnancy still eludes us. The biochemical concepts of 'facilitated anabolism' and 'accelerated starvation' were developed by Freinkel as explanations of the protective mechanisms for the baby during the stresses of pregnancy. Some of these nutritional stresses may also occur in the particular form of early childhood malnutrition known in Africa as kwashiorkor, where subcutaneous fat deposition, carbohydrate intolerance, islet hyperplasia and sudden death may follow a period of excess carbohydrate and deficient protein intake. Different feeding practices in different parts of the world make comparisons uncertain, but there is evidence for insulin resistance in both the macrosomic fetus of the hyperglycaemic mother and in the child with established kwashiorkor. These adaptive changes in early development may play both a physiological and a pathological role. Worldwide studies of hyperglycaemia in pregnancy are gradually establishing acceptable diagnostic criteria, appropriate screening procedures and an evidence base for treatment. Nevertheless the challenge of prediabetes and the big baby is still with us--in Jackson's words--'diabetes mellitus is a fascinating condition-the more we know about it the less we understand it'.

Macrosomic births at Mostar Clinical Hospital: a 2-year review

The aim of this research was to determine the incidence, risk factors and perinatal outcome of the macrosomic infants (birth weight > or = 4000 g). The retrospective research was performed using a case-control study conducted at Mostar Clinical Hospital. Total of 379 women gave singleton term births to macrosomic newborn in the period from January 1st, 2004 to December 31st, 2005 (observed group). Another 379 singleton normal birthweight term newborns (birth weight < 4000 g, but not small for gestational age), of the same maternal parity and age, who were delivered in the same period, formed the control group. The incidence of macrosomic births was 13, 1%. In the study group, significantly higher number of cases of postdatism (> 42 weeks of gestation) (P<0,001), maternal obesity (prepregnancy BMI> 26 kg/m2) (P<0,001), gestational diabetes mellitus (P=0,033), hypertension (P=0,025) and male infant (P<0,001) were observed. Cesarean delivery (P<0,001), intrapartal complications (cephalopelvic disproportion P<0.001, perineal trauma P=0,042) and newborn birth trauma (clavicular fracture P=0,038, brachial palsy P=0,021) occurred significantly more often in the macrosomic group. There was only one fetal death in the macrosomic group. In the control group there were no cases of perinatal deaths. To conclude, it is important to emphasize the significance of proper diagnosis of fetal macrosomia and management of macrosomic birth, since we have seen a growing number of macrosomic births during the last decades, and have faced a problem of increased risks of adverse perinatal outcome.

The influence of age at exposure to PBBs on birth outcomes

The determination of critical windows of susceptibility to environmental chemical exposures and health has become a major public health focus. This study examined the association between early age at exposure to polybrominated biphenyls (PBBs) and subsequent birth weight and gestational length in offspring among females. The study population consisted of 1111 births that occurred among 560 women enrolled in the Michigan PBB Cohort from 1975 to 1994. Maternal age at exposure was categorized into three groups:<10 years (n = 64), 11-16 years (n = 149), and 17-42 years (n = 347). Overall serum PBB levels ranged from 0 to 1490 ppb, with a median of 2, 3, and 2 ppb in the three age groups, respectively. Separate mixed-effects linear regression models were used to evaluate the effect of age at exposure (years) and initial PBB level (ppb) on birth weight (grams) and gestational age (weeks), controlling for gestational age (weeks) (in the model examining effects on birth weight), BMI (kg/m(2)) and serum PCB level at enrollment (ppb), maternal age and paternal education at delivery, parity, infant gender, interval between the initial serum test and date of delivery (years), and the trimester in which prenatal care was initiated. Relative to the oldest age group, age<10 years at exposure was the most important predictor of increased birth weight (estimated regression coefficient = 225 g, P = 0.012). Infant birth weight increased approximately 16 g for every 10 ppb increase in serum PBBs (P=0.004). There was no association between initial PBB levels and gestational age, nor were initial serum PCB levels associated with either infant birth weight or gestational length. These results provide support for the hypothesis that early age at exposure may be an important determinant in subsequent health effects due to environmental chemical exposures.

Optimal Gestational Weight Gain for Body Mass Index Categories

OBJECTIVE

To establish optimal gestational weight gain for each maternal body mass index (BMI) category based on significant risk estimates of adverse maternal and fetal outcome.

METHODS

The study population consisted of 298,648 singleton pregnancies delivered in Sweden between January 1, 1994, and December 31, 2004. The number of individuals in each weight gain class was compared with the number of individuals in all other weight gain classes in the same BMI group with regard to adverse maternal and fetal outcome. Odds ratios were calculated after suitable adjustments.

RESULTS

The optimal gestational weight gain in women by prepregnancy BMI was 9-22 lb (4-10 kg) for BMI less than 20; 5-22 lb (2-10 kg) for BMI 20-24.9; less than 20 lb (less than 9 kg) for BMI 25-29.9; and less than 13 lb (less than 6 kg) for BMI of 30 or more.

CONCLUSION

The gestational weight gain limits for BMI categories determined in this large population-based cohort study from Swedish Medical Registers showed that a decreased risk of adverse obstetric and neonatal outcomes was associated with lower gestational weight gain limits than was earlier recommended, especially among obese women.

Pre-pregnancy body mass index, gestational weight gain, and other maternal characteristics in relation to infant birth weight

OBJECTIVES

Infant birth weight is influenced by modifiable maternal pre-pregnancy behaviors and characteristics. We evaluated the relationship among pre-pregnancy body mass index (BMI), gestational weight gain, and infant birth weight, in a prospective cohort study.

METHODS

Women were enrolled at < or =20 weeks gestation, completed in-person interviews and had their medical records reviewed after delivery. Infant birth weight was first analyzed as a continuous variable, and then grouped into Low birth weight (LBW) (<2,500 g), normal birth weight (2,500-3,999 g), and macrosomia (> or =4,000 g) in categorical analysis. Pre-pregnancy BMI and gestational weight gain were categorized based on Institute of Medicine BMI groups and gestational weight gain guidelines. Associations among infant birth weight and pre-pregnancy BMI, gestational weight gain, and other factors were evaluated using multivariate regression. Risk ratios were estimated using generalized linear modeling procedures.

RESULTS

Pre-pregnancy BMI was independently and positively associated with infant birth weight (beta = 44.7, P = 0.001) after adjusting for confounders, in a quadratic model. Gestational weight gain was positively associated with infant birth weight (beta = 19.5, P < 0.001). Lower infant birth weight was associated with preterm birth (beta = -965.4, P < 0.001), nulliparity (beta = -48.6, P = 0.015), and female babies (beta = -168.7, P < 0.001). Less than median gestational weight gain was associated with twice the risk of LBW (RR = 2.04, 95% CI 1.34-3.11). Risk of macrosomia increased with increasing pre-pregnancy BMI and gestational weight gain (P for linear trend <0.001).

CONCLUSIONS

These findings support the need to balance pre-pregnancy weight and gestational weight gain against the risk of LBW and macrosomia among lean and obese women, respectively.

Macrosomia and hyperinsulinaemic hypoglycaemia in patients with heterozygous mutations in the HNF4A gene

BACKGROUND

Macrosomia is associated with considerable neonatal and maternal morbidity. Factors that predict macrosomia are poorly understood. The increased rate of macrosomia in the offspring of pregnant women with diabetes and in congenital hyperinsulinaemia is mediated by increased foetal insulin secretion. We assessed the in utero and neonatal role of two key regulators of pancreatic insulin secretion by studying birthweight and the incidence of neonatal hypoglycaemia in patients with heterozygous mutations in the maturity-onset diabetes of the young (MODY) genes HNF4A (encoding HNF-4alpha) and HNF1A/TCF1 (encoding HNF-1alpha), and the effect of pancreatic deletion of Hnf4a on foetal and neonatal insulin secretion in mice.

METHODS AND FINDINGS

We examined birthweight and hypoglycaemia in 108 patients from families with diabetes due to HNF4A mutations, and 134 patients from families with HNF1A mutations. Birthweight was increased by a median of 790 g in HNF4A-mutation carriers compared to non-mutation family members (p < 0.001); 56% (30/54) of HNF4A-mutation carriers were macrosomic compared with 13% (7/54) of non-mutation family members (p < 0.001). Transient hypoglycaemia was reported in 8/54 infants with heterozygous HNF4A mutations, but was reported in none of 54 non-mutation carriers (p = 0.003). There was documented hyperinsulinaemia in three cases. Birthweight and prevalence of neonatal hypoglycaemia were not increased in HNF1A-mutation carriers. Mice with pancreatic beta-cell deletion of Hnf4a had hyperinsulinaemia in utero and hyperinsulinaemic hypoglycaemia at birth.

CONCLUSIONS

HNF4A mutations are associated with a considerable increase in birthweight and macrosomia, and are a novel cause of neonatal hypoglycaemia. This study establishes a key role for HNF4A in determining foetal birthweight, and uncovers an unanticipated feature of the natural history of HNF4A-deficient diabetes, with hyperinsulinaemia at birth evolving to decreased insulin secretion and diabetes later in life.

Mode of delivery and the survival of macrosomic infants in the United States, 1995-1999

BACKGROUND

Although increases in perinatal mortality risk associated with fetal macrosomia are well documented, the optimal route of delivery for fetuses with suspected macrosomia remains controversial. The objective of this investigation was to assess the risk of neonatal death among macrosomic infants delivered vaginally compared with those delivered by cesarean section.

METHODS

Data were derived from the U.S. 1995-1999 Linked Live Birth-Infant Death Cohort files and term (37-44 wk), single live births to United States resident mothers selected. A proportional hazards model was used to analyze the risk of neonatal death associated with cesarean delivery among 3 categories of macrosomic infants (infants weighing 4,000-4,499 g; 4,500-4,999 g; and 5,000+ g).

RESULTS

After controlling for maternal characteristics and complications, the adjusted hazard ratio for neonatal death associated with cesarean delivery among the 3 categories of macrosomic infants was 1.40, 1.30, and 0.85.

CONCLUSIONS

Although cesarean delivery may reduce the risk of death for the heaviest infants (5,000+ g), the relative benefit of this intervention for macrosomic infants weighing 4,000-4,999 g remains debatable. Thus, policies in support of prophylactic cesarean delivery for suspected fetal macrosomia may need to be reevaluated.

Determinants of birthweight inequalities: population-based study

BACKGROUND

The aim of this paper is to study the whole spectrum of birthweight in a population-based birth cohort in order to document the role played by social factors, which complement physiological and behavioural factors, in the development of birthweight inequalities at the population level.

METHODS

The analyses were performed with data from the 'Quebec Longitudinal Study of Child Development 1998-2002 (QLSCD)'. The study follows a representative sample (n = 2103) of the children born in 1998 in the Canadian province of Québec.

RESULTS

Multivariate analyses adjusted for gestational age and mother's age indicate that mean birthweight was higher for boys than girls; improved with birth rank, mother's body mass index (BMI), and family socioeconomic status; and was lower for children of smoking mothers. Compared with children born to non-smoking mothers of higher socioeconomic status, the odds of having a low birthweight were between 6 and 12 times higher for children born to smoking mothers of lower or middle socioeconomic status. When maternal smoking status and mother's BMI are combined, socioeconomic status could still be seen to have a positive effect on mean birthweight except for overweight or obese smoking mothers, among whom the relationship between socioeconomic status and mean birthweight was reversed. In families of lower socioeconomic status, maternal smoking was the most important factor in birthweight inequalities, and in families of higher socioeconomic status, mother's BMI was the most important factor in birthweight inequalities.

CONCLUSION

This research is not only important for children in developed nations, but also for those in developing countries, where high birthweight and obesity are becoming more prevalent.

Shoulder dystocia: the unpreventable obstetric emergency with empiric management guidelines

OBJECTIVE

Much of our understanding and knowledge of shoulder dystocia has been blurred by inconsistent and scientific studies that are of limited scientific quality. In an evidence-based format, we sought to answer the following questions: (1) Is shoulder dystocia predictable? (2) Can shoulder dystocia be prevented? (3) When shoulder dystocia does occur, what maneuvers should be performed? and (4) What are the sequelae of shoulder dystocia?

STUDY DESIGN

Electronic databases, including PUBMED and the Cochrane Database, were searched using the key word "shoulder dystocia." We also performed a manual review of articles included in the bibliographies of these selected articles to further define articles for review. Only those articles published in the English language were eligible for inclusion.

RESULTS

There is a significantly increased risk of shoulder dystocia as birth weight linearly increases. From a prospective point of view, however, prepregnancy and antepartum risk factors have exceedingly poor predictive value for the prediction of shoulder dystocia. Late pregnancy ultrasound likewise displays low sensitivity, decreasing accuracy with increasing birth weight, and an overall tendency to overestimate the birth weight. Induction of labor for suspected fetal macrosomia has not been shown to alter the incidence of shoulder dystocia among nondiabetic patients. The concept of prophylactic cesarean delivery as a means to prevent shoulder dystocia and therefore avoid brachial plexus injury has not been supported by either clinical or theoretic data. Although many maneuvers have been described for the successful alleviation of shoulder dystocia, there have been no randomized controlled trials or laboratory experiments that have directly compared these techniques. Despite the introduction of ancillary obstetric maneuvers, such as McRoberts maneuver and a generalized trend towards the avoidance of fundal pressure, it has been shown that the rate of shoulder-dystocia associated brachial plexus palsy has not decreased. The simple occurrence of a shoulder dystocia event before any iatrogenic intervention may be associated with brachial plexus injury.

CONCLUSION

For many years, long-standing opinions based solely on empiric reasoning have dictated our understanding of the detailed aspects of shoulder dystocia prevention and management. Despite its infrequent occurrence, all healthcare providers attending pregnancies must be prepared to handle vaginal deliveries complicated by shoulder dystocia.