RISK-FACTORS FOR SMALL-FOR-GESTATIONAL-AGE INFANTS - A NEW-ZEALAND STUDY

Aim. The aim was to identify risk factors for small for gestational ag e infants. Method. Case-control study. The study population was 1800 i nfants selected randomly from all babies born over a three year period over 78% of the country. Of these 1800 infants, 85 (4.8%) were classi fied as preterm (<37 weeks completed gestation) and were excluded. 157 (8.9%) were classified as small for gestational age (cases) and 1519 (86.3%) were fullterm, nonsmall for gestational age infants (controls) . Risk factors were investigated using data collected from obstetric r ecords and parental interviews. Results. Risk factors associated with small for gestational age after controlling for potential confounders included maternal smoking during pregnancy (Odds ratio (OR) 2.61, 95% confidence interval (CI) 1.65, 4.15), primiparity (OR 2.96, 95% CI 1.5 9, 5.48), lack of antenatal care in the first trimester (OR 1.83, 95% CI 1.13, 2.98) and young age when mother left school (OR 1.56, 95% CI 1.01, 2.41). Use of marijuana in pregnancy significantly increased ris k of small for gestational age at the 6% level (OR=1.86, 95% CI 0.98, 3.52). The population attributable risk for maternal smoking was 31.1% (95% CI 18.2,41.9). Conclusion. Maternal smoking was the most, import ant modifiable risk factor in this dataset for small for gestational a ge.