The prevalence of alcohol consumption during pregnancy over 2007 and 2010 in two cross-sectional nation-wide samples of Dutch women is 22 % in 2007 and 19 % in 2010. One in five women do drink alcohol while pregnant. Most of the pregnant women drank alcohol at one occasion per month or less often. Prevalence of alcohol consumption was lower in 2010 compared to 2007 (p = 0.018); fewer women consumed alcohol, however the amount consumed per occasion had increased in 2010; one to three glasses of alcohol per occasion compared to less than one glass in 2007 (Table 1). Higher educated and older pregnant women were more likely to consume alcohol before, during and after pregnancy, as were women who smoke. During pregnancy of a 2nd baby, women seemed less likely to consume alcohol (Table 2). In our study, gestational age and birth weight were not associated with alcohol consumption during pregnancy, other features (symptomatic for FAS) have not been studied.
Our data were collected retrospectively and could have been subject to differential misclassification because of recall bias. On the other hand, the inquiry was primarily initiated to explore milk feeding practices and casually addressed alcohol consumption, so that more reliable estimates might have been obtained. Despite of the relatively low response of 40-51 % (although reasonable for this type of study, with no means of sending reminders to potential respondents), our data were representative for the Dutch population with respect to maternal age at child birth, gestational age and number of children and place of birth (home or hospital) and weighted for maternal education. For comparison, the Amsterdam based ABCD-study reported alcohol consumption in 36 % of pregnant women in 2003 . The Rotterdam based generation R study enrolled women between 2002 and 2005 and found 51 % used alcohol in early pregnancy and 37 % continued after pregnancy recognition . In 2007 we found a lower prevalence and even lower in 2010. These lower prevalences may reflect a trend over time of decreased prevalence of alcohol consumption during pregnancy, although differences in study designs and methodologies used may also have had some impact.
In Western Europe, prevalences of alcohol consumption during pregnancy differ between Sweden, 5.5 %, Germany 13.6 %, our study in the Netherlands 19-20 % and in France percentages between 12 % and 63 % [1–3]. Differences in prevalences of alcohol consumption during pregnancy might be related to the overall alcohol consumption in these countries. According to the WHO overall consumption by women aged 15+ years varied less in these countries: in Sweden, Germany, the Netherlands and France resp. 5.5, 7.0, 6.0 and 7.1 L pure alcohol are consumed yearly . Consumption in Germany during pregnancy also increased with higher age and educational level as in our study . And last but not least, advice given to pregnant women vary between countries and may also be responsible for differences between countries.
We have not asked the type of drink in our questionnaire. From other studies we know that the majority of women in the Netherlands drink beer or wine . A glass of wine contains 12 mL of pure alcohol, a glass of beer 12.5 mL (resp. 9.6 and 10 g of alcohol), therefore we assume the amount of alcohol to be 10 g alcohol per glass. The amount of alcohol consumed per occasion and the precise moment in pregnancy both determine the extent of damage to the developing infant. Conception and early pregnancy are most critical moments. Before pregnancy (recognition) the majority of women in our sample consumed alcohol (69 %), in the population of similar age and sex 78 % . Roughly three-quarters of women stopped alcohol consumption on pregnancy recognition, prior to this some drank at levels posing a risk . The recommendation to avoid alcohol during pregnancy may promote anxiety and feelings of guilt in women who have consumed alcohol before recognition. Risk awareness should therefore be taught already at school age or by computer-tailored interventions offered through midwives. A recent trial has been proven effective in stopping and reducing prenatal alcohol use .
Alcohol interferes with folate metabolism and reduces its bioavailability. A daily alcohol intake of >3 glasses causes folate deficiency , a risk for neural tube defects. In a large population-based study lower prenatal folate status during pregnancy also appears to impair behavioral development; it is associated with emotional problems in 3y old children . In the Netherlands, women of reproductive age are advised to take daily folic acid supplements 4 weeks before conception until 8 weeks after conception. Only half of the women use folic acid supplements in the conception period , those higher educated more often. We have no data on folic acid supplementation in our study sample. During the first three month of pregnancy alcohol consumption is less frequent, and in 2010 even lower compared to 2007 (14 % vs 17 %), however the amount of alcohol consumed has increased in 2010 (from <1 glass to 1–3 glasses of alcohol). Binge drinking (>6 glasses per occasion), mostly once per month, is reported in 0.4 % of our sample for both years. These women (a total of 17 in our surveys) appear to be at risk for folate deficiency ; identifying these women in clinical practice for targeted intervention may be of benefit.
Another substance with harmful effects on the developing infant is nicotine (cigarettes). In data from earlier surveys we found decreasing prevalences of smoking during pregnancy between 2001 and 2010. The prevalence of smoking differs strongly between women with different levels of education , being highest in those lower educated. We found that 2.5 % of the Dutch women both smokes and drinks during pregnancy, around 7 % smokes and does not consume alcohol, around 18 % consumes alcohol (numbers are slightly lower in 2010 compared to 2007). In 2007 70 % and in 2010 75 % of the pregnant women report they neither smoke nor consume alcohol. The combined effects on growth and development of both nicotine and alcohol are severe ; one in every 40 Dutch neonates of mothers who both smoked and drank enters life with lower gestational age and birth weight, growth retardation, respiratory disease, central nervous system abnormalities as well as behavioral and cognitive dysfunctions later in life.
In order to decrease this number, it is important to make women of childbearing age aware about risks of alcohol consumption (especially those higher educated) and smoking (especially those lower educated) during pregnancy, as well as benefits of folic acid supplement and breastfeeding. Preconception care can reduce infant mortality and morbidity. Since one in ten of pregnant women smoke and one in five consume alcohol, a considerable number of Dutch neonates’ health and quality of life can improve with an effective preconception care program that educates women of childbearing age about the risks of alcohol consumption and smoking.