Impact of delivery mode and gestational age on haematological parameters in Taiwanese preterm infants

Reference ranges of haematological parameters in preterm infants are limited. The aim of this study is to determine the reference values of haematological parameters in preterm infants in Taiwan, and to assess the impact of gestational age and mode of delivery on these parameters.

Medical records were retrospectively reviewed in preterm infants admitted to National Taiwan University Hospital from January 2001 to December 2004. The inclusion criteria included infants with <37 weeks of gestation who had blood sampling within 24 h of birth. The exclusion criteria included those with maternal history of antepartum haemorrhage, chorioamnionitis, fever, sepsis, preeclampsia and hypertension; and perinatal history of twin-to-twin transfusion syndrome, feto-maternal transfusion, injury and infection.

Of 568 preterm infants with blood cell counts, 337 were available for analysis. There were trends of increase in red blood cell counts, haemoglobin levels and haematocrit values as gestation increased up to 34 weeks. In contrast, a trend of decrease was noted in mean corpuscular volume values. There was an initial trend of decrease in white blood cell counts and then increased after 31 weeks gestation. The platelet counts were essentially unchanged. Infants born by vaginal delivery generally had higher haematological parameters than those born by Caesarean section at different gestational ages except for mean corpuscular volume values.

We established the reference ranges of haematological parameters in Taiwanese preterm infants. Health-care professionals must be cautious in clinical application of the haematological values because of varying antenatal and perinatal risk factors.