When is fetal macrosomia (> or = 4500 g) an indication for caesarean section?

Caesarean and vaginal deliveries of macrosomic infants weighing > or = 4500 g were studied, and pregnant women analysed by indication for caesarean section, presentation, parity and age. Both maternal and neonatal injuries occurred. Puerperal morbidity was noted in women delivered either by caesarean section or vaginally. The control group consisted of 321 parity- and age-matched pregnant women and their newborn infants weighing 3000-3499 g. The two groups were studied according to the same criteria. In the maternity unit of the General Hospital in Sibenik, Croatia, 10852 newborn infants were delivered (only singleton pregnancies included) between 1 January 1984 and 31 December 1993, of whom 321 (2.96%) weighed > or = 4500 g (290 weighing 4500-4999 g, and 31 weighing > or = 5000 g). Caesarean section was performed in 36 (11.2%) and 14 (4.4%) in the macrosomic and control groups, respectively (X2 = 10.50; P < 0.01). Of the 321 women with a macrosomic infant, 10 (3.1%) had a caesarean section for cephalopelvic disproportion and 7 (2.2%) for breech presentation. Caesarean section for vertex presentation was used more frequently in the macrosomic than in the control group (9.0% vs. 3.3%) (P < 0.01), as well as it was used for breech presentation (77.8% vs. 16.7%) (P < 0.01). As regards transverse and oblique lies, no difference was observed. The rates of macrosomic infants delivered from primiparous and grand multiparous women by caesarean section (i.e., 23.1% vs. 5.9% vs. 18.2%) were highly significant (X2 = 19.07; P < 0.001), as were the rates in adolescent pregnant women, in those of optimal childbearing age and in old pregnant women (60.0% vs. 9.0% vs. 26.9%) (X2 = 18.67; P < 0.001). Injuries were sustained by 28 (9.8%) women with a macrosomic infant delivered vaginally and by 12 (3.9%) controls (X2 = 6.25; P < 0.05). No maternal injuries were reported with caesarean delivery in either group. There was no birth trauma in the macrosomic and control infants delivered by caesarean section. With vaginal delivery birth trauma involved clavicular fracture (5.6%), brachial plexus palsy (2.8%) and central nervous system syndrome (2.1%). A total of 30 (10.5%) macrosomic infants and 4 (1.3%) controls, were identified as having birth trauma (X2 = 20.99; P < 0.001). No difference in puerperal morbidity rates were observed between the two groups with regard to caesarean and vaginal delivery (P > 0.05), showing significantly lower rates for vaginally delivered macrosomic infants (12.3% vs. 30.6%) (X2 = 8.51; P < 0.01). There was no perinatal death among those delivered by caesarean section in either group; however, when delivered vaginally, the rates were 0.70% (2 of 285) and 0.65% (2 of 307) for the macrosomic and control infants, respectively (P > 0.05). No women in either the macrosomic or control group died. In conclusion, decision making on management options when delivering a macrosomic infant depends on fetal presentation and maternal age and parity. Vertex presenting macrosomic infants weighing > or = 4500 g should be delivered vaginally, but liberal judgement is suggested in resorting to caesarean section delivery. Abnormal presentation, as well as malpresentations in primiparous women, are an absolute indication for caesarean section, whereas malpresentations in multiparous women are a relative (underlying) indication for caesarean section.