Some studies I found on PubMed.
4000 g = 8.82 lbs
4500 g = 9.92 lbs
5000 g = 11.02 lbs
Mode of delivery and the survival of macrosomic infants in the United States, 1995-1999.
* Boulet SL,
* Salihu HM,
* Alexander GR.
Centers for Disease Control and Prevention, National Center for Birth Defects and Developmental Disabilities, Atlanta, Georgia, USA.
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.
PMID: 17150065 [PubMed - in process]
Secular trends in cesarean delivery rates among macrosomic deliveries in the United States, 1989 to 2002.
* Boulet SL,
* Alexander GR,
* Salihu HM.
Department of Maternal and Child Health, School of Public Health, University of Alabama at Birmingham, Birmingham, AL 35294-0022, USA.
OBJECTIVES: We describe national trends in cesarean delivery rates among macrosomic infants during 1989 to 2000 and evaluate the maternal characteristics and risk factors for macrosomic infants delivered by cesarean section as compared to macrosomic infants delivered vaginally. STUDY DESIGN: We analyzed US 1989 to 2000 Natality files, selecting term (37 to 44 week) single live births to U.S. resident mothers. We compare macrosomic infants (4000 to 4499, 4500 to 4999 and 5000+ g infants) to a normosomic (3000 to 3999 g) control group. RESULTS: The proportion of cesarean deliveries among 5000+ g infants increased significantly over the time period. The adjusted odds ratio of cesarean delivery increased for all macrosomic categories over the 12-year period, as compared to normal birth weight infants. CONCLUSIONS: Rates of cesarean delivery among macrosomic infants continue to increase despite a lack of evidence of the benefits of cesarean delivery within this population. Further exploration of the rationale for this trend is warranted and should include the development of an optimal delivery strategy for such patients.
PMID: 16079908 [PubMed - indexed for MEDLINE]
A scoring system for detection of macrosomia and prediction of shoulder dystocia: a disappointment.
* Chauhan SP,
* Lynn NN,
* Sanderson M,
* Humphries J,
* Cole JH,
* Scardo JA.
Division of Maternal-Fetal Medicine, Aurora Health Care, West Allis, Wisconsin 53227, USA. firstname.lastname@example.org
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.
PMID: 17127493 [PubMed - indexed for MEDLINE]