After adjusting for social, economic, and cultural factors as well as for the age of the mother at childbirth and other potential confounders, we observed a significant increase in the percentage of health problems in infants when the parents were separated compared with situations in which the parental couple was intact.
Concerning the risk of SIDS and family structure in the literature
There are studies of the risk of SIDS that, on the one hand, confirm the predictors analyzed here (low birthweight, exposure to tobacco smoking, male infant, and feeding practices) and that, on the other hand, also note the link with the marital status of the mother. Of these studies [19,20] , let us take a Canadian retrospective case-control study of 1000 deaths that found using logistic regression an over-representation of newborns of non-married mothers (OR: 3.48; 95% CI: 2.94–4.11) [21]. Similarly, a Canadian prospective study that analyzed a cohort of more than 40 million infants born between 1995 and 2004 found a RR of SIDS of 1.7 (95% CI: 1.6–1.8) when the mother was single, taking mothers in a couple for reference [22]. There are also British retrospective studies that have found by means of univariate analysis an OR of SIDS of 3.00 (95% CI: 1.89–4.77) when the mother was single [23]. Yet these results cannot be compared to others: The focus has usually been on the fact that the mother was single, and not on parental separation and its possible corollary the blended family. Above all, the results described concerned cases of SIDS and not of ALTEs, for which we have not found any studies exploring a possible link with family structure. It should also be mentioned that in our study, the list of symptoms considered as frightening and sought for in the infants (Table 1) was much larger than the classical list pertaining to ALTE [17]. Furthermore, although the literature shows similarities in terms of risk factors [24], it appears that SIDS and ALTEs should not always be thought of as consequences of a single process [25]. Polysomnography is useful in very young children for detecting sleep disorders that require special care. Besides certain genetic malformations and abnormalities, the main indications for this examination are the testing for obstructive apnea, the snoring associated with nocturnal desaturation, gastroesophageal reflux, and laryngomalacia [26,27]. Our study brings to light a strong association between parental separation and abnormal polysomnography results. We cannot find any direct explanation for this observation in the literature. Investigations have linked certain nocturnal phenomena (snoring and other breathing noises, abundant sweating) to shorter sleep duration [28] or a less-advantaged socioeconomic environment [29], factors that may indirectly suggest the influence of parental behavior, which can vary depending on circumstances. For example the absence of exclusive breastfeeding is a risk factor for obstructive sleep apnea as well as for reflux and large regurgitation [30], but several literature reviews have reported the influence of marital status and of the presence of the infant’s father in decision-making with regard to breastfeeding, as well as that of the duration of breastfeeding [31,32]. In our study, the differences reported regarding breastfeeding behavior [33] cannot explain why the infants of mothers who do not speak French fluently are at a clearly lower risk of ALTE. Cultural habits relating to the sleep of infants should perhaps not be ruled out [34]. Our results did not reveal any confounder, even when taking into account the type of alimentation received (Table 4). A possible hypothesis would be the following: When the child’s parents do not live together, this would more often lead to a clinical picture meeting the criteria for reimbursement of home monitoring. Considering the transversal design of our study, we must admit that this is only a hypothesis.
Delayed psychomotor development (PMD)
In our sample, less than 2% of the infants displayed a psychomotor delay, and the adjusted OR was 1.3 (95% CI: 1.1–1.6) if there was parental separation. The literature gives us at least three possible explanations. The first points to the influence that the quality of both parents’ involvement in the upbringing of the infants has on the infants’ cognitive-behavioral development, as several systematic reviews and meta-analyses have illustrated [35,36]. A longitudinal study in 290 infants aged 24 to 36 months showed that the father’s involvement had a direct impact on the emergence of the infants’ developmental acquisitions, in particular that of language, while also having an indirect influence by improving the mother–child connection [37]. The second possible explanation recalls that the parental couple faces difficulties in the months following childbirth that increase the risk of maternal and paternal depression [38,39] and that this depression generates developmental disorders in infants [40,41]. Furthermore, several research works have shown that children that do not live together with both parents are more likely to be victims of child maltreatment or neglect. These are circumstances under which developmental retardation among children aged 0-6 years has been more frequently observed [42,43]. A link has been documented between the separation of the couple and violence between partners [44]. In 40% of cases, infants of 7 years of age and under witness this violence, the consequence of which is adjustment disorders [45]. Family doctors have observed the same problems: namely, violence between ex-partners and developmental disorders in infants after separation [14].
Body mass index (BMI)
In our sample, the BMI of 7% of the infants was above the 97th percentile, and 1% of the infants seemed thin, with a BMI below the 3rd percentile. We did not find any truly significant association between family structure and the risk for the infant of having a BMI <3rd percentile. However, when the mother had at least finished her secondary education, parental separation revealed an increased adjusted OR of 1.7 for a BMI >97th percentile. It should be noted that infants attain a BMI peak at the age of 7 months, after which BMI starts to decline from the eighth month onward. In other words, attaining a BMI >97th percentile at that age is possibly the beginning of an early adiposity rebound. The literature confirms that economic factors and some types of behavior (infant feeding practices, smoking tobacco during pregnancy, parental obesity, lifestyle) increase the risk of being overweight from early childhood onward [46-48]. However, no authors have directly linked family structure and early adiposity rebound. While several authors reveal an association between the parental engagement level from an educational or affective point of view and children’s overweight [49,50] or feeding practices [31,32], it is impossible as yet to confirm an explicative link between these research works and our observations.
Strengths and limitations of this study
Regarding the main independent variable, namely the family environment, we found that less than 7% 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]. Of note is that in the French-speaking part of Belgium, the percentage of families where the two parents are separated increases with the child’s age: in 2009, 6.6% of infants aged 6 to 11 months were living in such a setting, in comparison with 9% when considering children aged 28-32 months [51]. It is thus likely that the very low age of our study population accounts for the differing rates of separated couples encountered in our sample as compared to the overall child population (all ages confounded, 0 to 18 years).
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. In this context, it should be mentioned that the child’s psychomotor development, weight, and height were evaluated at the time of the assessment, and so in any case after a potential parental separation has been notified. However, some potential confounders were not available in our database, notably the child’s medical history, general health status, manner of sleeping or mother’s weight. At the preventive consultations, while the ONE agent enquires about the risk factors within the family and contributes to the safety promotion for low-age children in terms of sleeping manners, feeding, tobacco exposure, all information is not recorded in the case record forms. Although one of the strong points of our study is the size of the sample, involving nearly 80 000 subjects (20% of the population of that age in the French Community) [52], we noted some dissimilarities in comparison with the general population. For instance, we found a difference between the genders that was 1% lower than that normally observed for this age group (1.2% versus 2.2%) [53]. Similarly, very small birth weights (≤1999 g) taken together represented 1.9% in this study, as against 2.3% on a national level [54]. 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 in a specialized 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 39% of the women held a higher education degree, as against 25% generally in Belgium [55]. Moreover, in the studied population, 14% of families lived on only one (or two) replacement salary (dole or social assistance), and great caution must be exercised in comparing this data to the 20% pertaining to the 2012 general population [56]. We know that in Belgium, there exists a positive correlation between social level and general health status [57]. Given that our study sample comprised a greater proportion of better-off families as compared to the general population, it is possible that the observed differences in relation to family structure were less marked in the former than in the latter. Despite the differences cited, all the socio-cultural strata were represented in the study population, allowing us to make comparisons according to the socio-cultural level. Lastly, within our French-speaking Community of Belgium (Wallonia-Brussels Federation), there was no other access available to such a population - the least possible selected- of infants and young-aged children. 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 study [14] in family doctors and which is at the root of our current research question. 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 health of infants. Two other strong points of this study are that we aimed at a specific age group that had been the subject of little study beforehand with regard to the impact of family structure and, furthermore, that the data was collected by pediatric 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.