Advanced maternal age and smoking: Risk factors for admission to a neonatal intensive care unit

The aim of this study was to assess if advanced maternal age and cigarette smoking increased the requirement for admission to the neonatal intensive care unit (NICU) and if those factors acted synergistically. Retrospective analysis was made of 3518 singleton pregnancies receiving antenatal care and delivering at King's College Hospital from 1 January 1992 to 31 December 1992. The maternal age was greater than 35 years in 356 women (10.1% of the total) and 49 (13.8%) of those were cigarette smokers. There was an inverse relationship between maternal age and smoking. Two hundred and fifty-nine infants were admitted to the NICU. Logistic regression analysis revealed a significant relationship between maternal age and admission (p < 0.05), but no independent effect of maternal smoking. The proportion of infants from smoking mothers of advanced age (> 35 years) admitted to the NICU, however, was greater than that from young (less than or equal to 35 years) smoking mothers (p < 0.05). Advanced maternal age does increase the requirement for NICU admission and this effect is enhanced by smoking.