Shoulder dystocia: Incidence and Birthweight in Lampang Hospital

as the consequences, and the prevention. METHODS A retrospective analytical study was conducted in Lampang hospital. We retrieved data from electronics labour record between October 1st, 2003 to September 30th, 2010. Totally 19,507 infants were included to the study. The infants birthweight (BW) were 1,000 grams or greater. The logistic regression analysis was used to calculate odds ratio (ORs) and p-value of the shoulder dystocia incidence of each BW interval. Birth asphyxia (BA) was also assessed in both groups, with exact probability test. RESULTS We found 70 cases of shoulder dystocia from 19,507 infants, with vertex presen tation and vaginal delivery. The incidence was 0.36 percent, the lowest BW was 2,750 grams and the biggest one was 5,050 grams. We classifi ed the BW into interval of <2,500, 2,500 – 2,999, 3,000-3,499, 4,000-4,499 grams and 4,500 grams or greater. No shoulder dystocia was found in <2,500 grams. The incidence of shoulder dystocia increased with birthweight proportionally, with odds ratio 6.11, 39.51, 148.46 and 639.73 respectively, refer to 2,500-2,999 grams group (p-value<0.01). Mild and severe BA at 1 minute, mild BA at 5 minutes in the affected group were greater than the control group, ORs were 17.05(9.36-29.89), 18.07(4.62-50.97) and 27.43(12.68-54.23) signifi cantly, p-value<0.01. Additionally in severe BA at 5 minutes, the shoulder dystocia was greater than the control, ORs 5.18 (0.13-31.07) without statistic signifi cant (p-value=0.07). CONCLUSION The incidence of shoulder dystocia was increasingly associated with the BW and also the BA at 1 minute, mild BA at 5 minutes. But the severe BA at 5 minutes had no statistically signifi cant.