Must Macrosomic Fetuses be Delivered by a Caesarean Section? A Review of Outcome for 786 Babies ≥ 4,500 g

EDITORIAL COMMENT: The results in this large series of 786 fetuses with birth‐weight ≥ 4,500 g are so excellent that readers are urged to give careful attention to this paper in its entirety and not to stop at the summary! To emulate these results obstetricians must concentrate on how to select the 25% of cases in which Caesarean section was required (8.1% elective and 16.8% emergency) (table 3). It is noteworthy that in only 7 of the 786 fetuses presenting cephalically was elective Caesarean delivery deemed necessary for macrosomia alone (table 2). The main reason for the 132 emergency Caesarean sections were poor progress in the first stage of labour (101) and poor descent in the second stage (16) (table 3). It seems to us that timely recognition of these 2 situations explains the superior results obtained and highlights the area where good clinical judgement is required in these women having ‘trial of vaginal delivery’. It is noteworthy that there were only 4 cases of failed forceps and apparently none in which Caesarean section was performed for shoulder dystocia after the head had been born, although such extraordinary cases have been reported and are referred to by the authors. Perhaps the results in this series are so outstanding because of the amazingly high incidence of macrosomia in this Canadian population (2.3%)! The comparable figure from the Mercy Hospital for Women, Melbourne, 1980–1989 inclusive, was 1.37% (708 of 51,400 confinements). It is worth noting that the other popular measure of macrosomia, namely birth‐weight ≥ 10 pounds (4,540 g) reduces the above series to 1.14% (585 of 51,400). In the Melbourne series of infants with birth‐weight ≥ 4,500 g the Caesarean section rate was 21.3% (151 of 708). In this series of 708 there were no stillbirths and 3 neonatal deaths, 2 following Caesarean delivery (hydrocephalus, birth‐weight 4,650 g; intrauterine pneumonia plus hyaline membrane disease, birth‐weight 4,590 g with mother an insulin‐dependent diabetic) and 1 after vacuum extraction (meningomyelocele, fetal distress, birth‐weight, 4,770 g). The last paragraph of this paper sums up the ‘obstetrician's dilemma; to balance a low fetal risk from vaginal delivery against a low maternal risk from Caesarean section’. Summary: Because difficult vaginal delivery is more frequent with macrosomic fetuses, some writers recommend routine Caesarean section for the delivery of fetuses ≥ 4,500 g. The purpose of this study was to evaluate the appropriateness of this recommendation. A retrospective review was undertaken to determine how many fetuses born in our hospital weighing ≥ 4,500 g died or were permanently damaged as a consequence of mechanical difficulties at delivery. During a 10‐year period, 590 (75 o 7o) of 786 cephalic babies weighing ≥ 4,500 g and alive at the start of labour were born vaginally. No baby died or was permanently damaged as a consequence of mechanical difficulties at delivery. Routine Caesarean section for macrosomic fetuses to prevent death or damage from difficult delivery is not warranted by our results.