Why do pregnant women drink alcohol? The role of mental health, stress and personality in a national cohort of 90 000 mothers

Alcohol use during pregnancy poses serious health risks to the child such as prematurity, low birth weight, fetal death and fetal alcohol syndrome. As no lower safe limit for alcohol use during pregnancy is known, health authorities in many countries, including the USA and Norway, recommend total abstinence not only during pregnancy but also in the period when women try to conceive. Despite this, 25% - 50% of pregnant women report that they have consumed alcohol during pregnancy. A broad range of risk factors for alcohol use in pregnancy have been identified, such as low level of income, parity, the partner?s drinking behaviour, and alcohol use or abuse before pregnancy. With respect to psychological predictors, the trait of negative affectivity appears particularly relevant. Negative affectivity describes a stable tendency to frequently experiencing negative emotions such as depression and anxiety and to view the world and oneself in a negative light. Negative affectivity is associated with higher vulnerability to stress, more intense emotional reactions in daily situations, and a tendency to use intoxicating substances, including alcohol, when confronted with stress. To date, only a few smaller studies have investigated the association between negative affectivity and alcohol use in pregnancy, with inconsistent results. Most of these studies only had one assessment had a retrospective design or were based on very small samples. Important confounders such as alcohol use before pregnancy were not taken into account. This makes it difficult to evaluate if the observed risk of alcohol use in women high in negative affectivity was due to previous habitual use (and possibly alcohol dependence) or by stressors unique to the pregnancy. The aim of this project was to examine whether negative affectivity increased the risk of alcohol use during pregnancy, in the post-partum period, and until child age 36 months. The project is based on data from the Norwegian Mother and Child Cohort Study (MoBa) which includes more than 100 000 pregnancies. The MoBa is a large population based study which sought to survey every pregnant women in Norway from 1999 to 2008. Of the invited women, 39% agreed to participate and the attrition rate has been low. Mothers filled out questionnaires at gestational week 17 and 35, and at child age 6, 18 and 36 months. Due to the design of the MoBa study we had the opportunity to map the mothers alcohol use prior to, during, and after the pregnancy and investigate to what extent maternal negative affectivity has influenced her drinking pattern. The comprehensive amount of information on potential confounding factors such as level of education, income, and the partner alcohol consumption made it possible to adjust for these in the analyses and estimate the unique contribution of negative affectivity on maternal alcohol use. Our analyses revealed that very few women in the MoBa followed the health recommendations of alcohol abstinence also in the months prior to the pregnancy. Only 7% reported that they totally abstained from alcohol use three months prior to the pregnancy. Our analyses also revealed that a relatively large group of women neither followed the recommendation of not drinking alcohol while pregnant. 16% reported of a light alcohol use (0.5-2 alcohol units, 1-4 times a month) and 12% reported of binge drinking (an intake of more that 5 alcohol units in one sitting) during the first trimester of the pregnancy. During the second trimester 10% reported of light alcohol use and 0.5% reported of binge drinking. In depth analyses revealed that negative affectivity increased the risk of both light alcohol use and binge drinking both in the first and second trimester of the pregnancy. The risk of light alcohol use was roughly increased by 30% in both the first and second trimester for women high in negative affectivity. With regards to binge drinking the risk was even higher with an 60% increased risk during the first trimester and an more than doubled risk during the second trimester for women high in negative affectivity. All the results were adjusted for a long list of potential confounders. In the project we have also explored the association between negative affectivity and post-partum binge drinking, also whether the childs emotional and behavioural problems influences on maternal alcohol consumption. These results are not yet published and can therefore not be discussed in this summary.

Background: The risks associated with drinking alcohol in pregnancy are now well known. Despite this knowledge, 5-25% percent of the women continue to drink through the entire pregnancy and inflict potential harm upon themselves and their unborn child. Wh y these women continue drinking alcohol in pregnancy is poorly understood. Previous research has mainly focused on structural factors such as age, level of education, and civil status. In contrast, factors that are easier to modify through interventions s uch as mental health, stressful life events or personality have not been thoroughly examined. This project is based on data from the Norwegian Mother and Child Cohort Study and we will follow 90 000 pregnant women from the 17th gestational week until t he child is 3 years old. Information on alcohol drinking, maternal mental health, stressful life events and personality is assessed with questionnaires at the 17th and 30th gestational week and when the child is ½, 1½, and 3 years old. In addition 14 500 mothers are particpating with two pregnancies, which allows us to observe psychological variables that predict change and stability of drinking patterns from the first to the second pregnancy. We expect to find moderate to strong associations between our predictors (mental health, stress and personality) and our outcomes (heavy level of alcohol drinking before, during and after pregnancy). We also expect interactions between demographic variables such as education and psychological variables, such as anxiety, depression, eating problems, and personality. Increased knowledge of the causes and mechanisms for sustained alcohol drinking during and after pregnancy is the first step in devising screening tools and effective interventions that potentially could lower the number of women who drink heavily across and between pregnancies.