P.32 Smoking and substance misuse
Smoking status of the mothers at their time of booking was recorded for 320 (92.5%) of the 346 women. Of these, 52 (15.0%) were smokers at the time of booking. Twenty-three were smoking between one and nine cigarettes per day (n=23 of 52, 44.2%) and twenty-nine were smoking at least up to 10 cigarettes per day (n=29 of 52, 55.8%). Information on smoking in late pregnancy was available for 38 of the 52 smokers (73.1%) and only four (7.7%) stopped smoking during pregnancy. The prevalence of smoking during pregnancy or in the last trimester is not routinely known for all Irish pregnancies but rates of 12%, 15%, 16% and 19% have been reported for England, Northern Ireland, Wales and Scotland, respectively.

Three women had a documented history of alcohol misuse prior to pregnancy and two women had a documented history of alcohol misuse during pregnancy. Seven women had a documented history of drug misuse prior to pregnancy and six women had a documented history of drug misuse during pregnancy.

P.52 Primary prevention of preterm birth and the role of public health education
The identification of women at risk of preterm birth is important. Unfortunately, spontaneous PTB (sPTB) is a heterogeneous condition with multiple underlying aetiologies. However, it is worth drawing attention to some baseline patient characteristics, some of which were observed on our study population that may be amenable to primary intervention and result in a reduced risk of delivering a baby preterm.

Smoking has been significantly associated with preterm delivery with a meta-analysis of 20 prospective studies finding a relative risk (RR) of 1.27 with a 95% Confidence interval (CI) of 1.21-1.33 among women who smoked during pregnancy compared with non-smokers. In our study, 17% of women reported smoking at booking but comparative figures for the pregnant population are not available. It would seem prudent to support all pregnant women to quit smoking especially those at high risk of delivering a preterm infant.

The relationship between alcohol and illicit drug use during pregnancy and preterm birth is less clear. While no differences were noted between our study group and the comparison group, in light of the adverse foetal effects of alcohol use, it is not unreasonable to counsel women to consider abstaining entirely from alcohol during the periconception period. Cocaine and opiod abuse has also been associated with preterm birth with relative risks ranging from 2.8-3.5 compared to non-abusers. Women in maintenance methadone programmes are also at risk of preterm birth with a RR of 2.47 compared with patients not on opiates.