Correlation of birth weights with cesarean rates

Objective: To determine whether birth weights correlate with cesarean indic ations and whether a decrease in cesarean rates affects this relationship. Materials and methods: During the 1991-1997 period, 14 689 women delivered at Ravenswood Hospital Medical Center, Chicago; 2945 by cesarean (20.0%). W e studied birth weight groups (Group 1, less than or equal to 2500 g; Group 2, 2501-4000 g; and Group 3, >4000 g) according to the indication for cesa rean 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 separ ated the data into two periods: A (1991-1993) and B (1994-1997). The differ ences between proportions were analyzed using the chi(2) tables. A P < 0.05 value was considered significant. Results: 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 dys tocia increased with birth weight. In Group 3, one out of four newborns (on e 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). Conclusions: Birth weights af fect cesarean delivery rates. Small and large newborns have more cesarean d eliveries than those of average weight, whereas cesarean for dystocia incre ases with birth weights. Cesarean rates for non-reassuring fetal status are similar in all groups. A decline in repeat and cesareans for dystocia dete rmined the lower total cesarean rate during the second period. (C) 1999 Int ernational Federation of Gynecology and Obstetrics.