Does maternal smoking increase the risk of neonatal polycythaemia?

The objective of this observational study was to determine the relationship between tobacco smoking during pregnancy and neonatal Polycythaemia, and to assess the dose-response relationship. Thirty two pregnant women who smoked tobacco (cases), and ninety pregnant women who did not smoke (controls), were randomly selected from the annual obstetrics population in the Erinville hospital in Cork. This study was carried out over eighteen months and the subjects were seen three times, at 28, 32, and 36 weeks gestation. At each visit, a smokalyser test was preformed and the results were recorded. The subjects were also given charts to fill in the number of cigarettes they smoked each day for the four week period. Nicotine consumption milligrams per day was calculated depending on the brand they smoked. Finally, at labour, cord blood samples were obtained and sent for haemoglobin and haematocrit estimation. At the end of the study it was found that both cord blood haemoglobin and haematocrit were statistically significantly higher in smoking mothers, p < 0.01 and p < 0.001 respectively. The dose-response relationship was also statistically significant.