Correlation of birth weights with cesarean rates

To determine whether birth weights correlate with cesarean indications and whether a decrease in cesarean rates affects this relationship.

During the 1991-1997 period, 14 689 women delivered at Ravenswood Hospital Medical Center, Chicago; 2945 by cesarean (20.0%). We studied birth weight groups (Group 1, < or = 2500 g; Group 2, 2501-4000 g; and Group 3, > 4000 g) according to the indication for cesarean delivery. Group 3 was divided into two subgroups (3a: 4001-4500 g, and 3b: > 4500 g). As cesarean rates decreased in our unit after 1994, we separated the data into two periods: A (1991-1993) and B (1994-1997). The differences between proportions were analyzed using the chi2 tables. A P < 0.05 value was considered significant.

Two out of 10 women admitted to our unit were delivered by cesarean. Compared to Group 2 (average weight), rates for breech and 'other' indications were higher in Groups 1 and 3 (P < 0.001); the repeat cesarean rate was the lowest in Group 1. Rates for dystocia increased with birth weight. In Group 3, one out of four newborns (one out of three newborns > 4500 g in Subgroup 3b) had a cesarean birth, more than half of them for indications other than dystocia. Compared to Period A, Period B shows lower cesarean rates in Group 2 (21.4 vs. 16.4, P < 0.0001) and Subgroup 3b (35.4 vs. 26.1, P = 0.041).

Birth weights affect cesarean delivery rates. Small and large newborns have more cesarean deliveries than those of average weight, whereas cesarean for dystocia increases with birth weights. Cesarean rates for non-reassuring fetal status are similar in all groups. A decline in repeat and cesareans for dystocia determined the lower total cesarean rate during the second period. and snhtetricrr