Risk factors for preterm birth: a New Zealand study.
OBJECTIVE
To identify risk factors for preterm birth.


METHODS
A cross sectional study. The study population was 1800 infants selected randomly from all babies born over a three-year period. Of these, 85 (4.8%) were classified preterm (less than 37 completed weeks gestation). Data were collected from obstetric records and parental interviews.


RESULTS
Risk factors associated with an increased risk of preterm birth after controlling for potential confounders included smoking during pregnancy (adjusted relative risk (RR) = 2.7, 95% confidence interval (CI) = 1.3, 5.4), and multiple birth (adjusted RR = 48.8, 95% CI = 18.1, 131.4). Urinary tract infection was significant at the 7% level (adjusted RR = 2.3, 95% CI = 1.0, 5.6). Alcohol intake in third trimester was associated with a reduced risk of preterm birth (adjusted RR = 0.4, 95% CI = 0.2, 0.7).


CONCLUSIONS
Maternal smoking and multiple births were the most important modifiable risk factors in this study for preterm birth and may contribute to 17% and 11% of preterm births respectively.
Wright
S P
SP
Department of Paediatrics, University of Auckland.
Mitchell
E A
EA
Thompson
J M
JM
Clements
M S
MS
Ford
R P
RP
Stewart
A W
AW
D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008423:Maternal Age; D009520:New Zealand / Q000453:epidemiology; D007752:Obstetric Labor, Premature / Q000453:epidemiology; D016017:Odds Ratio; D011247:Pregnancy; D011272:Pregnancy, Multiple; D011897:Random Allocation; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors