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Læknablaðið 2006; 91: 191-5 Introduction: Caesarean section rates have increased over the past decades without a concomitant decrease in perinatal mortality. In Iceland the same trend has been seen while at the same time perinatal mortality rate has remained low. Most caesarean sections are done at term. Crude perinatal mortality rates give limited information about whether the increase in section rates leads to a lower perinatal death rate among term non-malformed singleton infants. The relation between caesarean section and perinatal mortality rates in singleton, non-malformed infants of birthweight ≥2500g in Iceland during 1989-2003 was studied. Materials and methods: Information about gestational length, birthweight, parity, onset of labour and previous caesarean section was collected on all singleton births ≥2500g from the Icelandic Birth Registration and from maternity case records. The same data were obtained for all perinatal deaths ≥2500g excluding malformed infants irrespective of mode of delivery. The caesarean section and perinatal mortality rates were calculated and the relation between these evaluated by Pearson´s correlation coefficient. Results: The total number of deliveries in the study period was 64514 and the mean perinatal mortality rate 6.4/1000 (range: 3.6-9.2/1000). A significant increase was found in the overall caesarean section rate, from 11.6% to 18.2% (p<0.001). There were 61633 singleton infants ≥2500 g and 8332 were born by caesarean section. There were 111 perinatal deaths among this cohort giving a mean perinatal mortality rate (PNMR) of 1.8/1000 (range 0.8-4.1/1000). While for singleton non-malformed infants the caesarean section rate increased from 10.4 % to 16.7% (p<0.001), the PMNR did not decrease significantly. For primiparous women the caesarean section rate increased from 12% to 18% with no correlation with the PNMR (0.6/1000). Conclusion: Despite a 60% rise in the caesarean section rate during the study period, no reduction of the perinatal mortality rate among infants ≥2500g was found in this population with a prior low perinatal mortality, neither among primi- nor multiparous women. Key words: caesarean section, perinatal mortality, term pregnancy, audit. Correspondance: Ragnheiður I. Bjarnadóttir, ragnhib@landspitali.is