Reduction in perinatal mortality among small for gestational age babies in New Zealand.

BACKGROUND: A significant reduction in perinatal mortality among births ≥1000 g has been observed in New Zealand. AIM: To determine, in a national cohort, if perinatal mortality has reduced in small for gestational age (SGA) and non-SGA babies. MATERIALS AND METHODS: Retrospective cohort, 2008-2016, of singleton non-anomalous births and perinatal deaths from 26+0 weeks gestation at birth in New Zealand. Perinatal deaths from the Perinatal and Maternal Mortality Review Committee data set were merged with the Ministry of Health national maternity data set. SGA was defined as less than the 10th customised birthweight centile using New Zealand coefficients. Perinatal mortality was defined as stillbirth from 26 weeks gestation and neonatal death up to the 27th day of life. RESULTS: There was a 30% reduction in perinatal mortality among SGA singleton non-anomalous babies at 26 weeks or more from 10.38/1000 births in 2008 to 7.28/1000 in 2016 (P = 0.046) but no significant change in mortality among appropriate and large for gestational age babies. CONCLUSION(S): There has been a significant reduction in perinatal mortality among SGA babies in New Zealand. The mechanism for this reduction is unclear.