Determinants of smoking and cessation during and after pregnancy

Abstract

Smoking during pregnancy is an important public health issue. An assessment of the full spectrum of the psycho-emotional and sociodemographic determinants of maternal smoking is essential to the development of effective smoking cessation interventions. The purpose of this research was to identify key predictors of pregnant smoking from the data collected in a large longitudinal study - the Mater -University Study of Pregnancy (MUSP), in which the original objectives were to determine the multifactorial impact of psychosocial factors on obstetric outcomes. Data were collated at two stages. At their first clinic visit, women were asked to describe their smoking levels before becoming pregnant and currently, and these women were interviewed when the child was six months old. Information on smoking and cessation at different stages (ie, before, during and after pregnancy) was available from 6688 women (78.2 percent of the initial cohort). Information on a wide range of variables was collected. They included smoking habit, sociodemographic, psychological and emotional factors, physical activity, and life events. The results indicate that 48.6 percent, 37.6 percent and 43.4 percent of women were smokers before pregnancy, at the first clinical visit and after six months of child's birth, respectively. 23.3 percent of women who had smoked before pregnancy quit smoking when they found out they were pregnant and 56.1 percent of them who quit smoking during pregnancy relapsed to smoking by six months postpartum. Logistic regression analyses show that 17 variables were potential predictors of pregnant smoking (p ≤ 0.043). They included young age, poor education, unemployed, aboriginality, single women, living in flats/units, trying marijuana, drinking alcohol, drinking coffee during pregnancy, having problem with law, didn't think partner overjoyed with pregnancy, didn't plan to get pregnant, often watching TV and didn't do physical exercises. Further analyses reveal that some variables exhibited an apparent trend in relation to smoking status during pregnancy. For example, during the pregnancy women who watched TV between one to three hours per day or more than three hours per day, the odds ratio was 2.20 (95 percent CI: 1.34 - 3.61) and 2.86 (1.75 - 4.70), respectively, compared with those who never watched TV during pregnancy. 11 variables were significantly associated with successful cessation of smoking during pregnancy (p ≤ 0.033). They included socioeconomic status (eg, high family income, no previous marriage, and nulliparous status), no substance abuse (eg, "didn't try marijuana pre-pregnancy", "didn't drink alcohol and coffee during pregnancy"), psycho-emotional factors ( eg, "felt overjoyed with pregnancy", "think partner felt happy with pregnancy", "agreed with partner"), and physical exercises. More than half (56.1 percent) of the women who quit smoking during pregnancy relapsed to smoking by six months postpartum. Compared with light smokers (ie, 1-9 cigarettes/day), odds ratio for smoking relapse among heavy (≥ 20 cigarettes/day) or moderate smokers (10-19 cigarettes/day) was 1.22, (95 percent CI: 0.87 - 1.71) and 1.16 (95 percent CI: 0.80 - 1.69), respectively. Logistic regression analyses indicate that young age (OR for the age groups ≤24 and 25-29 years: 1.99 [95 percent CI: 1.06-3.73] and 1.52 [0.81-2.84], respectively), family income (OR for A$5,200-10,399, A$ 10,400- 15,599 and ≥ A$ 15,600: 3.00 [1.08 - 8.33], 4.58 [1.53 - 13.68] and 3.77 [1.25 - 11.34], respectively) non-breastfeeding (OR = 2.72 [1.53 - 4.84]), and drinking alcohol after pregnancy (OR = 1.62 [l.00 - 2.63]) were the strong predictors of relapse postpartum. Many factors are associated with smoking and cessation during pregnancy. Improved understanding of the motivators and barriers of pregnant smoking can assist in the development of the most effective public health intervention strategy. This is one of the world's largest cohort studies to examine the relationship between pregnant smoking and a wide range of psychosocial factors. It is envisaged that the most effective public health intervention strategy can only be developed by an increasingly sophisticated understanding of the motivators and barriers to smoking behaviour change before, during and after pregnancy. As various measures for tobacco control are implemented both in Australia and other developed countries, it is anticipated that the prevalence of smoking in the general population will continue to decline. However, because of multifactorial influences ( eg, stress, industrial targeting, and increased social acceptance), there is a trend that the prevalence of smoking in teenagers, particularly in females, is increasing. It is a cause for concern since most of the women who smoke will continue to smoke when they are pregnant. One of the urgent and important public health tasks is to reduce and control the usage of tobacco among teenagers. On the other hand, much research needs to be done to identify a full spectrum of major determinants of pregnant smoking and to formulate rational, cost-effective, and science-based intervention strategies to reduce the prevalence of smoking among pregnant women. As an important public health area, smoking control programs for teenagers and pregnant women clearly need more support from governments, industries and communities. Appropriate public health policies (eg, more resources for monitoring, intervention and evaluation) are critical for achieving all these goals