Comparison with other studies

Smoking in the infants’ environment: The short-term risks for infants that are linked with smoking tobacco in their environment are well documented, with an increase in respiratory infections, symptoms of allergy and sudden death, among others.16–19 The report on childhood in Belgium “Portrait de l'enfance en Belgique” was published in 20046 and showed that parents were more often smokers and/or depressive when separated. In the focus-group study in 2006, the family doctors observed distress among separated parents, a corollary of this being high-risk behaviour (including smoking).10 Indeed, arguments confirm the link between difficulties in life (among which the separation of couples is cited) and the use of tobacco, among other things.20 ,21 Our adjusted results showing a greater risk of tobacco smoking in the environment of infants when the parents are separated therefore appear to be consistent with those that are to be found in the literature, which also gives us a possible explanation: the separation leads to ill-being in the adults in question. The lower risk for infants of being exposed to tobacco smoking when the mother speaks little or no French may be explained by the fact that the majority of women of non-Belgian descent come from cultures in which it is rarer for women to smoke tobacco.22

Vaccination schedule: As part of the ONE’s preventive consultations, the hexavalent and pneumococcal injections are performed free of charge and automatically. This explains their excellent distribution among infants. The percentage of infants vaccinated was 99% for the hexavalent vaccine and 92% for the pneumococcal vaccine. This difference in percentage can be explained for the pneumococcal vaccine by its more recent introduction into the schedule (2007) and by the time it took for the vaccine to come into use across all the vaccination centres—that is, from 2008 onwards. In Belgium, immunisation against rotavirus has been recommended since 2007, but, as explained in the Methods section, besides the fact that this vaccine was not totally free, parents had to buy it themselves in a pharmacy. In our population, the infants of separated parents were less often vaccinated against rotavirus, an effect that persisted after adjustment had been made for sociocultural environment. We cannot entirely exclude that this significant result may be accounted for by income differences depending on the family situation. However, one hypothesis could be that separated parents are less available for carrying out certain tasks for their children because they do not have the time or because of multiple worries or even ill-being. There is little analysis in the literature of the link between family structure and vaccination cover. Thus, a systematic review published in 2008 attempted to identify the predictive factors of non-adherence to the vaccination schedule in Western countries. Though it listed difficulties of a social, cultural and financial nature as well as the level of education, the level of knowledge of vaccines, the age of the mother, the type of health insurance and so on, no reference was made to the family environment.23 On the other hand, a Flemish study of 14-year-old adolescents showed a significant association between the lack of proper vaccination (MMR, hepatitis B, meningitis C) and social, cultural, financial and educational determinants, but also single parent families following a divorce.24 An American study of a sample of more than 20 000 infants aged 19–35 months showed by means of univariate and bivariate analyses that the maternal characteristics that were the most associated with incomplete vaccination, besides the known sociocultural determinants, were large families, widowhood and parental separation.25 If differing behaviour with regard to vaccination was indeed confirmed in parental separation, infants’ risk of infection could also be different, as some prospective studies have already observed.8 Indeed, it should be remembered that in a qualitative study in 2006, Belgian family doctors were disappointed to observe both a higher frequency of infection in infants and a difficulty in obtaining compliance with the vaccination schedule following parental separation.10 In our sample, the other risk factors for non-compliance with the vaccination schedule against rotavirus were consistent with what is to be found in the literature—namely, a lack of education, the very young age of mothers, as well as when French is not their first language.

Exclusive breast feeding: Parental separation—after adjustment had been made for sociocultural environment, the age of the mother and certain characteristics of the infant such as birth weight and sex—was significantly associated with less-than-optimal nutrition. That is, the infant was not exclusively breast fed as often or for as long as the infants of non-separated couples. Besides the importance of the socioeconomic conditions and level of education of the mother, several literature reviews have reported that decision-taking with regard to breast feeding as well as its duration were influenced by marital status and the presence of the infant’s father.26 ,27 An Australian study has described results that are consistent with ours. This cohort study of nearly 2500 women showed that, after adjusting for socioeconomic and biomedical factors, the OR of stopping breast feeding at 4 months or less after childbirth as compared with more than 4 months was around 1.3 (95% CI 1.1 to 1.7) when the mother had experienced a stressful event during pregnancy, in particular separation of the parental couple.28 The results linking environmental factors other than family structure and infant nutrition can be summarised as follows: in the most comfortable families, and when mothers are educated, the infant is breast fed longer. However, an exception should be noted: the infants of mothers of non-Belgian descent are more often given the recommended nutrition despite lower income and a lower level of maternal education, as has been reported by other European authors.29 Furthermore, when the infant’s birth weight was low, there is a greater risk of no breast feeding, as has been regularly described in the literature.30 ,31 Finally, in our sample, girls seemed to have been breast fed for a significantly shorter duration. The majority of authors have not found32 or have not looked for this association. However, the link with the infant’s sex is sometimes documented,33 mainly in Africa.

Strengths and limitations of this study

Regarding the main independent variable, namely the family environment, we found that 6.6% of the infants lived under parental separation by adding the ‘parents separated’ and ‘infant only sees one parent’ categories together. This percentage seems low given national statistics,7 but it is not negligible when one considers that the average age of mothers in Belgium at separation is around 44,34 whereas the average age of the mothers in our sample was 29. The very young age of the infants is a factor that must be taken into account as well. As regards our results, caution should be exercised owing to the methods employed. The cross-sectional nature of our study results in uncertainty with regard to time: Theoretically, we do not know the direction of causality between the variables, and we have no idea of the length of time the infants were exposed to parental separation, nor whether their parents were separated or not when they were born. Only the implementation of longitudinal studies with sufficiently large sample sizes of children followed up since conception could provide us with insights about the mechanisms underlying our study results. One of the strong points of our study is the size of the sample, which was nearly 80 000 participants (20% of the population of that age in the French Community).35 We noted some dissimilarities in comparison with the general population. For instance, we found a difference between the sexes that was 1.4% lower than that normally observed for this age group (1.2% vs 2.6% at 1 year of age).36 Similarly, very small birth weights (≤1999 g), when taken together, represented 1.9% in this study, as compared with 2.3% on a national level.37 A possible explication is that boys and infants with a very low birth weight have higher morbidity, and it may be that they are more often followed up in a specialised medical setting than in preventive consultation at the ONE. We cannot exclude the possibility that the socioeconomic circumstances mentioned may also explain these differences. Indeed, in our sample, nearly 32% of the women held a higher education level, as against 25% generally in Belgium.38 However, all the general population levels were represented in our sample size (though to different extent), which must be stressed, as our study aimed to draw comparisons between exposed (parents separated) and non-exposed participants (parents living together). The observation that our studied population appeared to be better off than the general population reinforces our hypothesis that there appears a link between family structure (parents living together or not) and parental behaviour that is independent of social status. We can therefore defend the concept that this bias reinforces our conclusions. Although our study results were adjusted for several essential socioeconomic indicators, it is worth noting that we have omitted to include parameters pertaining to the father's situation. This was purposely done in order to avoid losing too many observations. We have also omitted to include any variable concerning family income specifying the number and type of salaries per family, instead of income levels. In spite of these limitations, what also confirms our interpretation is that this study was undertaken in response to a ‘clinical impression on the ground’ of first-line doctors, which was later documented in a focus-group study10 in general practitioners and which is at the root of our current research topic. What is more, we have seen that the Western, and in particular European, literature has reported studies (including prospective studies) whose results support this idea of the negative impact of parental separation on the quality of the environment of infants. Two other salient points arising from this study were: (1) we focused on a specific age group that had scarcely been studied beforehand regarding the association between family structure and factors influencing health; (2) the full data were collected by paediatric healthcare professionals. We believe that these results are noteworthy, and for us this confirms the usefulness of conducting both research into other age groups and prospective studies.

Conclusions and implications for general practitioners

Our study confirms the need for primary and secondary preventive action that aims at the families of young children with regard to driving smoking out of homes, complying with vaccination schedules and obtaining optimal nutrition, and in particular for the poorest families, in which the adult members are less informed about their health and their children’s health. In this regard, the proactivity of family doctors remains essential, because almost all the families in this country have an appointed family doctor whom 90% of adults and 70% of children see at least once a year (four times a year on average). We also know that the more families experience socioeconomic difficulties, the more they go to see their doctor.39 What these results reveal is that parental behaviours are significantly less adequate when parents are separated. Even though this study does not give any explanation about the reasons for these observations (parents and children chronically stressed? parental psychopathology? more restrictive schedules? relationship issues within blended families? etc), it makes us step back from the idea that the development of the children of separated parents is less than optimal only because of a financially more precarious environment. It seems worthwhile when dealing with families who have an infant or infants aged under 12 months to recommend that family doctors make it standard practice to enquire about family composition. In the event of parental separation and regardless of socioeconomic situation, the family doctor can then be even more attentive with regard to the infant’s health (smoking in their environment, vaccinations, nutrition). Moreover, research could be started into whether there is a need to inform young couples who wish to start a family about the impact of the family environment on the infant’s health—without lecturing or preconceptions on the doctor’s part. Finally, in Belgium, it is already advised that every time family doctors have contact with a pregnant woman or a family with a young child or children they enquire about the quality of the partners’ relationship.40 ,41 Our results confirm the validity of this approach, which makes it possible to support couples who are often in difficulty during pregnancy and in the months that follow childbirth. It can be presumed that if the recommendations proposed are properly understood—that is, applied in a kind and understanding manner and people are not stigmatised—then the benefits, however small, will in all cases outweigh the resulting risks. This merits investigation within the profession at any rate.