Study population
This study was conducted in Malmö. Malmö is situated in the southwest part of Sweden. It is the third largest town in the country, with a population of about 300 000 inhabitants. It is a multiethnic city, with 30% of its inhabitants having been born abroad [15]. The study was population-based and cross-sectional. The study population comprised 8-month-old children from Malmö, who visited the Child Health Care (CHC) centersduring 2003-2007 for their 8-months check-up, and whose parents answered a self-administered questionnaire (n = 9,289 children; 65% of those who received the questionnaire). The CHC centersin Sweden are a well-established organization with a strong tradition, monitoring children's physical and developmental health in order to reduce mortality, morbidity, and disability among babies and young children. The CHC centers offer base programs including regular visits until the child is 5-6 years old, controlling his or her weight, height, hearing, sight, and physical and psychological development, as well as administering vaccinations according to the base program. Some of the visits are conducted with a nurse, and some with a nurse and a physician. The CHC centers support and educate parents concerning childcare and child development. The CHC focus is prevention; visits are voluntary and the consultations are free of charge. As many as 99% of children aged 0-5 participate [16].
The questionnaire contained approximately 30 questions about issues such as the parents' educational level, country of birth, social support, and the child's medical care consumption and housing. It also included questions about maternal smoking during pregnancy, presence of secondhand tobacco smoke and breastfeeding. The questionnaire was validated and translated into five different languages: Albanian, Arabic, English, Serbo-Croatian, and Somali [17].
Maternal educational level
Maternal educational level was based on years of schooling and divided into lower educational level (i.e., 9 years or less), medium educational level (i.e., 10-12 years), and higher educational level (i.e., more than 12 years of education).
Parental and child characteristics
Parents' country of birth was divided into: both parents born in Sweden, one parent born in Sweden, and both parents born outside Sweden. Low birth weight was defined as < 2500 g, and normal birth weight as ≥ 2500 g. Number of children at home was assessed through the question: "How many children aged 0-18 do you have at home?"
Social support
Emotional support (given to the parents) was assessed with the question: "Do you have someone who can give you proper personal support to cope with life's stresses and problems?" with answers being classified into high emotional support ("yes, definitely" or "yes, probably") and low emotional support ("not for certain" or "no"). Practical support (given to the parents) was assessed with the question: "Would you be able to get help from someone to look after your child, within the same day?", with answers being classified into low practical support ("not for certain" or "no") and high practical support ("yes, definitely" or "yes, probably").
Preventive behavior
Breast feeding, tooth brushing, and participation in parental preventive programs
Length of breastfeeding was dichotomized into <4 and ≥4 months of exclusive breastfeeding. Difficulties with breastfeeding were assessed through the question: "Has the child's mother had any breastfeeding problems?" with response alternatives: "Yes" or "No". The types of breastfeeding problems were further assessed through the question: "If yes, what kind of problem?" with response alternatives: "Difficulties getting milk production started"; "Insufficient breast milk"; "Sore nipples"; "The child had difficulty suckling"; "Other, please specify?". More than one type of problem could be reported. Having brushed the child's teeth was assessed through the question: "If the child has any teeth, have you started to brush them?" with response alternatives of "Yes" or "No". Parental training was assessed through CHC-journals, in which the nurse stated whether or not the parents had taken part in a parental educational program. The parental training program includes information and discussions about issues such as delivery and parenthood.
Risk behavior
Smoking during pregnancy and secondhand tobacco smoke
Maternal smoking during pregnancy was divided into yes and no. Exposure to secondhand tobacco smoke during early life (when the child was 0-4 weeks of age) was divided into no (no exposure at all) and yes (daily exposure, including smoking outside).
Medical care consumption
Having sought care from a doctor during the last 8 months in addition to the regular CHC-visits was categorized into "Yes" or "No". In-hospital stay was assessed through the question: "Has the child been admitted to hospital during the last 8 months?" with response alternatives of "Yes" or "No".
Statistical methods
Proportions with 95% confidence intervals of parental preventive behavior (length of exclusive breastfeeding, tooth brushing, participation in parental educational program), parental risk behavior (maternal smoking during pregnancy and secondhand tobacco smoke), and social support (low emotional support, low practical support) were analyzed in relation to maternal educational level. The odds of medical care consumption, (doctor's visits and in-hospital care), were analyzed in relation to exposure to one, two or three unfavorable parental behavioral factors (exclusive breastfeeding <4 months, maternal smoking during pregnancy, and secondhand tobacco smoke) by logistic regression. Logistic regression was further used to analyze the associations between maternal educational level and the child's medical care consumption. Multiple logistic regression analyses were performed in order to adjust the estimated OR for covariates. Model 1 included year, sex, parents' country of birth, low birth weight and number of children at home; model 2 included model 1 with additional adjustment for low emotional support and low practical support; and model 3 included model 2 with additional adjustment for maternal smoking during pregnancy, secondhand tobacco smoke at 0-4 weeks; and length of exclusive breastfeeding. Statistical analyses were performed with version 17.0 of SPSS for Windows. The study was approved by the Regional Ethical Committee, Lund University.