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The Netherlands has a unique system for promoting child and youth health, known as the preventive Child and Youth Healthcare service (CYH). The CYH makes an important contribution to the development and health of children and young people by offering (anticipatory) information, immunisation, and screening, identifying care needs and providing preventive support to children and their families from birth up to the age of 18 years. The CYH is offered free of charge and offers basic preventive care to all children and special preventive care to children who grow up in disadvantaged situations, such as children growing up in poverty or in a family where one of the members has a chronic health condition. Basic care is supported by 35 evidence-based guidelines and validated screening tools. Special care is supported by effective interventions. The impact of the CYH is high. It is estimated that every EUR 1 spent on the CYH provides EUR 11 back. Although the Dutch CYH is a solid public health system with a reach of up to 95% among young children, the access to this service could be further improved by paying more attention to health literacy, making special care available to all children in need and improving transmural and integrated care coordination. In addition, the generation of nationwide data could help to demonstrate the impact of the CYH and will direct and prioritise the necessary care. By continuously developing care on the basis of new (scientific) insights and (societal) issues, the CYH will continue to offer all children in the Netherlands the best preventive healthcare.

Background: Little is known about costs and effects of vision screening strategies to detect amblyopia. Aim of this study was to compare costs and effects of conventional (optotype) vision screening, photoscreening or a combination in children aged 3-6 years., Methods: Population-based, cross-sectional study in preventive child health care in The Hague. Children aged 3 years (3y), 3 years and 9 months (3y9m) or 5-6 years (5/6y) received the conventional chart vision screening and a test with a photoscreener (Plusoptix S12C). Costs were based on test duration and additional costs for devices and diagnostic work-up., Results: Two thousand, one hundred and forty-four children were included. The estimated costs per child screened were €17.44, €20.37 and €6.90 for conventional vision screening at 3y, 3y9m and 5/6y, respectively. For photoscreening, these estimates were €6.61, €7.52 and €9.40 and for photoscreening followed by vision screening if the result was unclear (combination) €9.32 (3y) and €9.33 (3y9m). The number of children detected with amblyopia by age were 9, 14 and 5 (conventional screening), 6, 13 and 3 (photoscreening) and 10 (3y) and 15 (3y9m) (combination), respectively. The estimated costs per child diagnosed with amblyopia were €1500, €1050 and €860 for conventional vision screening, €860, €420 and €1940 for photoscreening and €730 (3y) and €450 (3y9m) for the combination., Conclusions: Combining photoscreening with vision screening seems promising to detect amblyopia in children aged 3y/3y9m, whereas conventional screening seems preferable at 5/6y. As the number of study children with amblyopia is small, further research on the effects of these screening alternatives in detecting children with amblyopia is recommended., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Public Health Association.)

The aim of this cross-sectional study was to assess differences in caries experience according to socio-economic status (SES) in a health-care system with full coverage of dental costs for children up to the age of 18 yr. In 2011 and 2014, by performing hurdle negative binomial models, we obtained data on 3,022 children and young adults aged 5, 8, 11, 14, 17, 20, and 23 yr, living in four cities in the Netherlands. At all ages between 5 and 23 yr, the percentages of children with caries-free dentitions were lower and mean caries experience were higher in low-SES than in high-SES participants. In 5-yr-old children with dmft > 0, mean caries experience was 3.6 in those with low SES and 2.3 in those with high SES. In 23-yr-old participants, these estimates were 6.8 and 4.4, respectively (P < 0.05). Low-SES children have a greater risk of more caries experience than high-SES children. Thus, in a system with full free paediatric dental coverage, socio-economic inequality in caries experience still exists. Dental health professionals, well-child care doctors and nurses, general practitioners, and elementary school teachers should collaborate to promote oral health at the community level, with specific targeting of low-SES families. We further need policy measures to curtail, at community level, the increasing availability and consumption of highly processed, carbohydrate-rich foods, with particular attention for low-SES families., (© 2019 The Authors. Eur J Oral Sci published by John Wiley & Sons Ltd.)

The diet of young children is an important determinant of long-term health effects, such as overweight and obesity. We analyzed two-day food consumption records from 1526 young children (10-48 months old) attending 199 daycare centers across The Netherlands. Data were observed and recorded in diaries by caregivers at the day nursery and by parents at home on days that the children attended the daycare center. According to national and European reference values, the children had an adequate nutrient intake with exception of low intakes of total fat, n-3 fatty acids from fish and possibly iron. Intakes of energy and protein were substantially higher than recommended and part of the population exceeded the tolerable upper intake levels for sodium, zinc and retinol. Consumption of fruit, fats, fish, and fluids was substantially less than recommended. The children used mostly (semi-)skimmed milk products and non-refined bread and cereals, as recommended. Two thirds of the consumed beverages, however, contained sugar and contributed substantially to energy intake. In young children, low intakes of n-3 fatty acids and iron are a potential matter of concern, as are the high intakes of energy, protein, sugared beverages, and milk, since these may increase the risk of becoming overweight.

Vitamin D insufficiency during pregnancy is associated with disturbed skeletal homeostasis during infancy. Our aim was to investigate the influence of adherence to recommendations for vitamin D supplement intake of 10 μg per day (400 IU) during pregnancy (mother) and in the first months of life (child) on the occurrence of positional skull deformation of the child at the age of 2 to 4 months. In an observational case-control study, two hundred seventy-five 2- to 4-month-old cases with positional skull deformation were compared with 548 matched controls. A questionnaire was used to gather information on background characteristics and vitamin D intake (food, time spent outdoors and supplements). In a multiple variable logistic regression analysis, insufficient vitamin D supplement intake of women during the last trimester of pregnancy [adjusted odds ratio (aOR) 1.86, 95% (CI) 1.27-2.70] and of children during early infancy (aOR 7.15, 95% CI 3.77-13.54) were independently associated with an increased risk of skull deformation during infancy. These associations were evident after adjustment for the associations with skull deformation that were present with younger maternal age and lower maternal education, shorter pregnancy duration, assisted vaginal delivery, male gender and milk formula consumption after birth. Our findings suggest that non-adherence to recommendations for vitamin D supplement use by pregnant women and infants are associated with a higher risk of positional skull deformation in infants at 2 to 4 months of age. Our study provides an early infant life example of the importance of adequate vitamin D intake during pregnancy and infancy., (© 2014 John Wiley & Sons Ltd.)

Objective: To estimate the prevalence of alcohol consumption during pregnancy in the Netherlands in 2007 and 2010., Method: During two identical, nation-wide surveys in 2007 and 2010, questionnaires were handed out to mothers of infants aged ≤6 months who visited a Well-Baby Clinic. By means of the questionnaire mothers were, in addition to questions on infant feeding practices and background variables, asked about their alcohol consumption before, during and after pregnancy. Logistic regression analyses were used to look into relationships of alcohol consumption with maternal and infant characteristics., Results: We obtained 2,715 questionnaires in 2007, and 1,410 in 2010. Within 6 months before pregnancy, 69 % of women consumed alcohol (data from 2010). During pregnancy 22 % consumed alcohol in 2007, 19 % in 2010. During the first three months of pregnancy, 17 % (2007) and 14 % (2010) of mothers consumed alcohol. Alcohol consumption was mainly one glass (~10 g alcohol) on less than one occasion per month. Compared to 2007, in 2010 more women consumed 1-3 or >3 glasses alcohol per occasion (resp. 11 % to 7 % and 1.4 to 0.7 %). Older women and those with a higher education consumed more alcohol, as did smokers. Birth weight, gestational age and weight for gestational age were not associated with alcohol consumption. In 2007 and 2010, 2.5 % resp. 2.4 % of pregnant women both smoked and consumed alcohol; resp. 70 % and 75 % did neither., Conclusion: In contrast to Dutch guidelines which advice to completely abstain from alcohol, one in five women in the Netherlands consume alcohol during pregnancy.

We aimed to estimate the proportion of Dutch postmenopausal breast cancer cases in 2010 that is attributable to lifestyle-related risk factors. We calculated population attributable fractions (PAFs) of potentially modifiable risk factors for postmenopausal breast cancer in Dutch women aged >50 in 2010. First, age-specific PAFs were calculated for each risk factor, based on their relative risks for postmenopausal breast cancer (from meta-analyses) and age-specific prevalence in the population (from national surveys) around the year 2000, assuming a latency period of 10 years. To obtain the overall PAF, age-specific PAFs were summed in a weighted manner, using the age-specific breast cancer incidence rates (2010) as weights. 95 % confidence intervals for PAF estimates were derived by Monte Carlo simulations. Of Dutch women >40 years, in 2000, 51 % were overweight/obese, 55 % physically inactive (<5 days/week 30 min activity), 75 % regularly consumed alcohol, 42 % ever smoked cigarettes and 79 % had a low-fibre intake (<3.4 g/1000 kJ/day). These factors combined had a PAF of 25.7 % (95 % CI 24.2-27.2), corresponding to 2,665 Dutch postmenopausal breast cancer cases in 2010. PAFs were 8.8 % (95 % CI 6.3-11.3) for overweight/obesity, 6.6 % (95 % CI 5.2-8.0) for alcohol consumption, 5.5 % (95 % CI 4.0-7.0) for physical inactivity, 4.6 % (95 % CI 3.3-6.0) for smoking and 3.2 % (95 % CI 1.6-4.8) for low-fibre intake. Our findings imply that modifiable risk factors are jointly responsible for approximately one out of four Dutch postmenopausal breast cancer cases. This suggests that incidence rates can be lowered substantially by living a more healthy lifestyle.

Objective: To calculate the proportion of cancer cases in the Netherlands in 2010 that were attributable to lifestyle factors by using the most recent data., Design: Secondary analysis., Method: Lifestyle risk factors studied were tobacco smoking, alcohol consumption, overweight, lack of physical exercise, and six elements of diet (consumption of vegetables, fruit, processed meat and red meat, and calcium and fibre intake). The lifestyle factors were organised so that the group with the highest risk (e.g. smokers) could be compared with the groups with the lowest risk (e.g. ex-smokers, non-smokers). Cut-off points were in line with Dutch public health messages. We obtained prevalence data on risk factors from national databases. Relative risks for the relationship between lifestyle and cancer were based on the international literature. Incidence and mortality data for cancer in 2010 were obtained through the Netherlands Cancer Registry. We calculated percentages of new cancer cases and deaths for men and women and for each type of cancer individually; these were then summed., Results: We estimated that of the 98,971 newly-diagnosed cases of cancer among persons aged ≥ 20 years in the Netherlands in 2010, 29,938 (30%) were attributable to the above-mentioned lifestyle factors. Smoking was the most important contributory risk factor (19% of all new cancer cases), followed by sub-optimal dietary habits (10%), overweight (4%), alcohol consumption (3%), and lack of physical activity (2%). Of cancer deaths in 2010, an estimated 38% were attributable to lifestyle factors. Projections for 2020 show that lack of exercise and consumption of alcohol and meat will contribute less to the development of cancer while overweight and a reduction in inadequate dietary fibre intake and inadequate fruit and vegetable consumption will contribute more., Conclusion: Almost one-third of all cases of cancer and almost 40% of deaths from cancer can be attributed to a less healthy lifestyle.

Objective: To establish trends in the prevalence of smoking during pregnancy between 2001 and 2010 and to relate these to differences in educational gradient in the Netherlands., Design: National surveys., Method: In 2001, 2002, 2003, 2005, 2007 and 2010, 28,720 questionnaires were handed out to mothers with infants aged up to 6 months at periodic check-ups at well baby clinics. A total of 16,358 (57%) mothers completed this questionnaire., Results: Between 2001 and 2010, the number of women who smoked daily during their pregnancy dropped by half. In 2010 6.3% (95% CI: 5.0-7.6) smoked. The prevalence of smoking was highest among mothers with a low level of education (13.8% in 2010; 95% CI 9.3-18.4%) and lowest among mothers with a high level of education (2.4% in 2010; 95% CI 1.2-3.6). Four percent of pregnant smokers stopped smoking during pregnancy. Women limited the median number of ten cigarettes per day during the six months prior to pregnancy to five per day during pregnancy. The difference in prevalence of smoking in pregnancy between women with a low level of education and those with a high level of education was 18.9% in 2001 and 11.4% in 2010. The difference in smoking prevalence between mothers with an average level of education and mothers with a higher level education was 6.5% in 2001 and 5.4% in 2010., Conclusion: Between 2001 and 2010, the percentage of women who smoked throughout pregnancy dropped by half. In 2010, 6.3% of Dutch pregnant women were still smoking. The prevalence of smoking differed strongly between different levels of education and this difference did not change during the study.

Background: Tobacco smoking is a major cause of morbidity and mortality, including during pregnancy. Although effective ways of promoting smoking cessation during pregnancy exist, the impact of these interventions has not been studied at a national level. We estimated the prevalence of smoking throughout pregnancy in the Netherlands and quantified associations of maternal smoking throughout pregnancy with socioeconomic, behavioural, and neonatal risk factors for infant health and development., Methodology/principal Findings: Data of five national surveys, containing records of 14,553 Dutch mothers and their offspring were analyzed. From 2001 to 2007, the overall rate of smoking throughout pregnancy fell by 42% (from 13.2% to 7.6%) mainly as a result of a decrease among highly educated women. In the lowest-educated group, the overall rate of smoking throughout pregnancy was six times as high as in the highest-educated group (18.7% versus 3.2%). Prenatal tobacco smoke exposure was associated with increased risk of extremely preterm (

Aim: The aim of this study was to gain insight into contraception practised and related to breastfeeding duration., Methods: Mothers with infants up to 6 months received a questionnaire on infant feeding (breast or formula feeding) and contraception (hormonal or non-hormonal methods). Estimates of the time interval between resuming contraception and cessation of lactation was calculated by Chained Equations Multiple Imputation., Results: Of all women (n = 2710), 30% choose condoms, 22% the combined oral contraceptive pill (OCP) and few other methods. Breastfeeding was started by 80%, and 18% continued up to 6 months. Of the breastfeeding mothers, 5% used hormonal contraception; 7% of women who used hormonal contraception practised breastfeeding. After adjustment for background variables, the use of OCP is strongly associated with formula feeding: after delivery to the third month postpartum, the crude OR being 17.5 (95% CI: 11.3-27.0), the adjusted OR 14.5 (9.3-22.5); between the third and sixth month postpartum, respectively, 13.1 (95% CI: 8.6-19.9) and 11.7 (7.6-17.9). Of all breastfeeding women, 20-27% resumed OCP at 25 weeks postpartum and 80% introduced formula feeding. The time lag between these events is 6 weeks. Hormonal contraception was resumed after formula introduction., Conclusion: Mothers avoid hormonal contraception during lactation; they change to formula feeding 6 weeks before they resume the OCP. To effectively promote longer duration of breastfeeding, the BFHI needs to address contraception as practised.

Objective: To investigate whether false-positive outcomes on neonatal hearing screening cause long-lasting parental concerns., Methods: A general population of parents whose children had participated in the universal neonatal hearing screening (UNHS) programme were examined. Parents filled out a questionnaire 6 months after UNHS. Outcomes were compared for all parents whose child tested positive or inconclusive in at least one of three tests but afterwards proved not to have hearing impairment (cases, n = 154) and a random sample of parents whose child passed the first test (controls, n = 288). Parental anxiety as measured with the State-Trait Anxiety Inventory (STAI), attitude towards the child (child health rating and experienced problems) and sensitivity to hearing problems were measured., Results: Median STAI score was equal for cases and controls. Parental attitudes toward the child also did not differ. The difference in the proportion of parents who worried about their child's hearing was statistically significant between cases and controls (p = 0.001) and varied with the number of screens; 4% of controls were worried about the child's hearing, as compared to 10% of cases whose children were tested twice, and 15% of cases whose children were tested three times., Conclusions: False-positive UNHS test results do not cause long-term general parental anxiety. However, 6 months after screening, a considerable proportion of parents continued to experience hearing-specific worries regarding their child.

Objective: To establish smoking prevalence of fertile-aged women; before and during pregnancy, and 6 months after delivery., Design: Cross-sectional., Method: Yearly surveys by questionnaires handed out during 2001-2003 to mothers visiting a Well Baby Clinic with infants aged 0-6 months., Results: Out ofa total of 14,540 questionnaires, 9133 (63%) were completed and returned. Before pregnancy 25% of all the women concerned smoked, 6% stopped 6 months before getting pregnant; this percentage rose between 2001 (5%) and 2003 (7%). During pregnancy, 14% of the women smoked. This percentage was significantly lower in 2002 and 2003 (13%) compared to 16% in 2001. 11% smoked while pregnant (average 5 cigarettes daily), and 3% stopped some time during pregnancy. Of the mothers who quitted smoking before or during pregnancy, two thirds did so permanently. Nevertheless 15% of all women smoked during the first half year after delivery. This percentage was lowest in 2003 (14%) and highest in 2001 (17%). 28% of all mothers with infants aged 0-6 months had partners who smoked (daily 10 cigarettes average), these women were more likely to start smoking again (RR: 2)., Conclusion: Minor positive changes were observed within the study period. A smoking partner contributed to smoking relapse after delivery.

Context: Patients with thyroidal congenital hypothyroidism (CH-T) born in The Netherlands in 1981-1982 showed persistent intellectual and motor deficits during childhood and adulthood, despite initiation of T(4) supplementation at a median age of 28 d after birth., Objective: The present study examined whether advancement of treatment initiation to 20 d had resulted in improved cognitive and motor outcome., Design/setting/patients: In 82 Dutch CH-T patients, born in 1992 to 1993 and treated at a median age of 20 d (mean, 22 d; range, 2-73 d), cognitive and motor outcome was assessed (mean age, 10.5 yr; range, 9.6-11.4 yr). Severity of CH-T was classified according to pretreatment free T(4) concentration., Main Outcome Measure: Cognitive and motor outcome of the 1992-1993 cohort in comparison to the 1981 to 1982 cohort was the main outcome measure., Results: Patients with severe CH-T had lower full-scale (93.7), verbal (94.9), and performance (93.9) IQ scores than the normative population (P < 0.05), whereas IQ scores of patients with moderate and mild CH-T were comparable to those of the normative population. In all three severity subgroups, significant motor problems were observed, most pronounced in the severe CH-T group. No correlations were found between starting day of treatment and IQ or motor outcome., Conclusions: Essentially, findings from the 1992-1993 cohort were similar to those of the 1981-1982 cohort. Apparently, advancing initiation of T(4) supplementation from 28 to 20 d after birth did not result in improved cognitive or motor outcome in CH-T patients.

Context: The Dutch T(4)-TSH-TBG-based neonatal screening program detects patients with congenital hypothyroidism (CH) of thyroidal (CH-T) as well as central (CH-C) origin. The numbers and characteristics of true-positive and false-positive referrals will differ from other, predominantly TSH-based, screening methods., Objective: The present study describes the characteristics of the referred neonates, both CH patients and false positives, and of the reported CH patients with a false-negative screening result born in the study period., Design, Setting, Patients, and Main Outcome Measure: For each referred child born between April 1, 2002, and May 31, 2004, screening results and first venous sample results were recorded and classified as transient or permanent CH-T or CH-C or as no CH., Results: In the study period, 430,764 children were screened. Of the 772 children with abnormal screening results, 224 (29%) had CH; another 13 CH patients did not have abnormal screening results, giving an overall CH incidence of 1:1800. Incidences of permanent CH, permanent CH-T, permanent CH-C, and transient CH were 1:2200, 1:2500, 1:21,000, and 1:12,000, respectively. The most frequent explanations for the 548 false-positive referrals (71% of the referred cohort) were severe illness and TBG deficiency (occurring in 198 and 200 children, respectively)., Conclusions: The Dutch incidence figures for CH belong to the highest worldwide, suggesting that the T(4)-TSH-TBG screening program is an efficient method to detect CH of variable etiology and severity. Still, a small percentage of children with CH escaped detection via this screening approach. Severe illness and TBG deficiency appear to be responsible for the majority of false-positive referrals.

This study examines the factors that influence parents' decisions to have their children vaccinated under the Dutch National Immunisation Programme. A computer questionnaire was sent to 500 parents in 1999 (the response rate was 98.2%). The intention to vaccinate was most strongly determined by attitudes. The belief that vaccination is safe and the best way to protect children against infectious diseases positively influenced parents' attitudes. The idea that children receive too many vaccines simultaneously and that vaccination interferes with natural development had a negative effect on attitudes. Dutch parents believe that doctors only inform them about the benefits of vaccination and disregard possible drawbacks. Since attitudes did not appear to be the result of thorough deliberation, parents could easily be influenced by negative publicity about vaccination. Educational campaigns and practitioners' advice should provide complete information about all aspects of the question, enabling parents to make well-considered and therefore enduring decisions.

Aim: The aim of the study was to describe infant feeding practices and associated factors, and to explore mothers' main reasons for starting and stopping breastfeeding., Methods: We performed a national inquiry into milk feeding practices among 9133 Dutch infants aged < 7 mo by means of a questionnaire., Results: 78% of mothers initiated breastfeeding. At 1 and 4 mo, respectively, 51 and 25% of infants were fed primarily on human milk; after 6 mo, only 15% of mothers still provided human milk as the only source of milk feeding. During the whole 6-mo period, another 11 to 18% was fed on both breast and formula milk. Women initiating breastfeeding were more likely to be higher educated, have a higher-educated partner, be non-smokers, have a full-time job, and be primiparous. In addition, breastfeeding initiation rate was higher for women born outside the Netherlands. Longer duration of breastfeeding was mostly found amongst higher-educated, non-smoking women. The odds for continuation of breastfeeding after 4 mo increased when mothers' working hours did not exceed 16 h/wk. Infant delivery at home was associated with a higher initiation rate as well as longer duration of breastfeeding compared to hospital delivery. Infants born after 38 wk of gestation, with a birthweight of 3500 g had higher odds to be breastfed for a longer period., Conclusion: Only a minority of Dutch infants is breastfed for 6 mo. Maternal and infant characteristics are important predictors of breastfeeding initiation and duration.

Context: Since the introduction of screening for congenital hypothyroidism (CH) in 1974, the optimal laboratory strategy has been the subject of debate., Objective: To assess the clinical effectiveness and cost-effectiveness of various types of thyroxine (T(4))-based strategies to screen for CH., Design, Setting, and Participants: In the Netherlands, since January 1, 1995, a primary T(4) determination with supplemental thyroid-stimulating hormone (TSH) and T(4)-binding globulin (TBG) measurements has been used. Results were calculated from cumulative findings for 1181079 children screened between January 1, 1995, and December 31, 2000., Main Outcome Measures: Rates of detection of patients with CH of thyroidal origin (CH-T) or CH of central origin (CH-C), false-positive rates, laboratory costs, and costs of initial diagnostic evaluations., Results: All known infants (n = 393) with CH-T and 92% (n = 66) of infants with CH-C were detected on the basis of low T(4) levels, TSH elevation, and/or low T(4)/TBG ratios. If the decision to refer had been based solely on TSH elevation, then 94% of patients with CH-T and none of the patients with CH-C would have been detected. If low T(4) levels (

Aim: To examine the association of excessive infant crying with maternal smoking during and after pregnancy, paternal smoking, and smoking by other people in the living environment of the infant., Methods: We collected data on infant crying and smoking in a Dutch national sample of 5845 infants aged 0-3 mo (response 62.8%). We defined excessive crying as crying over 3 h a day on more than 3 d of the preceding week., Results: The prevalence rate of excessive crying was 4.0% (95% CI 3.5 to 4.5%). Excessive crying occurred more frequently among infants of fathers smoking 15 + cigarettes/d (odds ratio (OR) 1.99, 95% CI 1.38 to 2.86) and of mothers smoking 10 + cigarettes/d during pregnancy (OR 1.86, 95% CI 1.02 to 3.42). Infants whose parents were heavy current smokers or whose mothers had been so during pregnancy had a 69% higher prevalence of excessive crying than infants of non-smoking parents (rates: 6.3% and 3.7%, respectively; odds ratio 1.80; 95% CI 1.26 to 2.57)., Conclusion: Parents stopping smoking may prevent excessive infant crying.

Background: In the Netherlands, there is a very low incidence of sudden infant death syndrome (SIDS) due to effective preventive campaigns., Methods: During the period September 1996 to August 2002, nationwide 161 deaths from SIDS (about 85% of all cases of SIDS during that time) were investigated by the Cot Death Committee of the Dutch Paediatric Association., Results and Discussion: Over 10% of cases of SIDS took place during some type of child care. From a national survey carried out in 2000/01 information was available on the child care attendance of 2000 Dutch infants aged 3-6 months. Based on the hours usually spent in child care by these infants, the number of similarly aged infants that died from SIDS while attending child care was 4.2 times higher than expected. Remarkably, the prevalence of known risk factors for SIDS, such as sleeping position and parental smoking, was favourable in the SIDS cases in child care settings. The adherence of child care facilities to the safe sleeping recommendations is high in the Netherlands, and no explanation as to why child care settings may be associated with an increased risk of SIDS is apparent. The possibility of other explanations, such as stress and change in routine care, is hypothesised.

Objective: Our purpose was to evaluate whether effects of exposure to environmental levels of PCBs and dioxins on development in the Dutch cohort persist until school age., Study Design: In the Dutch PCB/dioxin study, cognitive and motor abilities were assessed with the McCarthy Scales of Children's Abilities in children at school age. During infancy, half of this population was fully breast-fed for at least > or = 6 weeks and the other half formula fed. Prenatal exposure to PCBs was defined as the sum of PCB118, 138, 153, and 180 in maternal and cord plasma. In breast milk, additional measurements of 17 dioxins, 6 dioxin-like PCBs, and 20 nondioxin-like PCBs were done., Results: Negative effects of prenatal PCB and dioxin exposure on cognitive and motor abilities were seen when parental and home characteristics were less optimal. These effects were not measurable in children raised in more optimal environments., Conclusions: Neurotoxic effects of prenatal PCB and dioxin exposure may persist into school age, resulting in subtle cognitive and motor developmental delays. More optimal intellectual stimulation provided by a more advantageous parental and home environment may counteract these effects of prenatal exposure to PCBs and dioxins on cognitive and motor abilities.

Unlabelled: Polychlorinated biphenyls (PCBs) and dioxins are environmental pollutants. Prenatally, as well as postnatally through breast feeding, large amounts are transferred from mother to the child. Formula is free of these substances. Considering their potential developmental neurotoxicity, we investigated long term effects of perinatal exposure to PCBs and dioxins on neurological and cognitive development. Given the evidence that PCBs exert oestrogenic effects, and oestrogens are known to suppress lactation, we investigated the effect of maternal PCB body load on lactation performances as well., Methods: A group of 418 infants were followed from birth up to 6 years of age. Half of them were fully breast fed (BF) for at least 6 weeks. Prenatal PCB exposure was measured from cord and maternal blood. Postnatal exposure was reflected by PCB and dioxin levels in breast and formula milk and plasma PCB levels at 42 months of age. Both neurological and cognitive development were taken as outcome variable at 18, 42 months and at 6 years of age. At 18 and 42 months of age neurological condition was evaluated according to Hempel and at 6 years of age according to Touwen. Condition was evaluated in terms of optimality. Separately, the fluency of movements was scored. Cognitive abilities were measured at 18 months by the Bayley Scales of Infant Development, at 42 months of age by the Kaufman Assessment Battery for Children (K-ABC) and at 6 years of age by the McCarthy Scales. Daily breast milk volume and milk fat content in relation to PCB body load was evaluated in 102 mothers. Multivariate regression models were applied to analyse associations of measured exposure variables with independent variables adjusted for confounders., Results: At 18 months of age cognitive development was not affected by either pre- or postnatal exposure to the measured PCBs and dioxins. However, neurological examination showed an adverse effect of prenatal exposure to the measured pollutants on neurological optimality score. At 42 months of age we found negative associations between prenatal PCB exposure on cognitive development. However no effect was demonstrated on postnatal exposure to the measured pollutants. Neurological development was not affected by either pre- or postnatal exposure to PCBs and dioxins. At 6 years of age the preliminary results revealed evidence that cognitive development is affected by prenatal exposure to these pollutants in children from young mothers. An adverse effect of prenatal exposure on neurological outcome was also demonstrated in the formula fed group but not in the breast fed group. Despite a higher PCB exposures from breast milk we found at 18 months, 42 months of age, and at 6 years of age a beneficial effect of breast feeding on the quality of movements, in terms of fluency, and on the cognitive development tests. Maternal PCB body load was inversely related to 24-h breast milk volume and milk fat content., Conclusion: These data give evidence that prenatal exposure to PCBs do have subtle negative effects on neurological and cognitive development of the child up to school-age. Human breast milk volume and fat content is adversely affected by the presently encountered PCB levels in W. Europe. Our studies showed evidence that breast feeding counteracts the adverse developmental effects of PCBs and dioxins.

Objective: To study possible adverse effects of environmental exposure to polychlorinated biphenyls (PCB) and dioxins on cognitive functioning in young children., Methods: In a follow-up of the Dutch PCB/Dioxin study, cognitive abilities were assessed with the Kaufman Assessment Battery for Children in 42-month-old children (n = 395). In a subgroup (n = 193) verbal comprehension was assessed with the Reynell Language Developmental Scales. Prenatal PCB exposure was estimated from the sum of PCBs 118, 138, 153, and 180 (SigmaPCB) in maternal plasma. Lactational exposure was assessed from breast milk PCB and dioxin concentrations, multiplied by the number of weeks of breast-feeding. Current PCB body burden was estimated from SigmaPCB in 42-month-old plasma samples., Results: After adjustment was done for covariables, maternal SigmaPCB was associated with lower scores on the overall cognitive and sequential and simultaneous processing scales of the Kaufman Assessment Battery for Children (all P <.05). The highest exposed group (SigmaPCB >/= 3 microg/L) scored 4 points lower on all 3 scales of the K-ABC when compared with the lowest exposed group (SigmaPCB < 1.5 microg/L). Both lactational exposure and current exposure to PCBs and dioxins were not related to 42-month cognitive performance., Conclusions: In utero exposure to "background" PCB concentrations is associated with poorer cognitive functioning in preschool children. Children of mothers at the upper end of exposure are especially at risk. Therefore maternal PCB body burden should be reduced, and breast-feeding should not be discouraged.

This study investigated the effect of early feeding mode on the neurological condition at 42 months. For this purpose, healthy pregnant women were recruited in Groningen and Rotterdam, The Netherlands. Children were healthy and born at term. At 42 months, the children were neurologically examined by means of the Touwen/Hempel technique. In addition to the clinical diagnosis, the neurological findings were interpreted in terms of optimality. Special attention was paid to the quality of movements in terms of fluency. In total, 200 (51%) exclusively breastfed(for > or = 6 weeks) and 194 (49%) formula-fed children were studied. Twelve (3%) 42-month-old children were considered to be neurologically mildly abnormal and 1 child was diagnosed as abnormal. No effect of the type of feeding was found on the clinical diagnosis or the neurological optimality. After adjustments for study centre and social, obstetric, perinatal and neonatal neurological differences, a beneficial effect of breastfeeding on the fluency of movements was found (odds ratio for non-optimal fluency 0.56; 95% confidence interval 0.37-0.85). The prolongation of full breastfeeding beyond 6 weeks did not influence the quality of movements. In conclusion, among Dutch preschool children, there was a small advantageous effect of full breastfeeding during the first 6 weeks of life on the fluency of movements.

We analyzed polychlorinated biphenyls (PCBs) in s.c. adipose tissue, liver, and brain of nine fetuses who died in utero. Their median (range) gestational ages and birth weights were 34 (17-40) wk and 2050 (162-3225) g. Three fetuses were small for gestational age. The levels of PCB congener nos. 118, 138, 153, and 180, and the sum of these (sigmaPCB), were calculated in terms of tissue total fat content (ng/g fat). The median (range) sigmaPCB (in ng/g fat) amounted to adipose tissue 235 (97-768), liver 198 (67-362), and brain 50 (22-122). Median (range) sigmaPCB levels in liver and brain were 0.8 (0.4-0.9) and 0.2 (0.1-0.3) times, respectively, as high as the sigmaPCB levels in adipose tissue. There were strong relations between sigmaPCB in adipose tissue and sigmaPCB in liver (r=0.98; p < 0.01), and between sigmaPCB in adipose tissue and sigmaPCB in brain (r=0.91; p < 0.01). Adipose tissue, liver, and brain did not show differences in the distribution of congeners 118, 138, 153, and 180, and there was no statistically significant association between tissue PCB levels and gestational age (r varied between 0.22 and 0.47). Median sigmaPCB levels in fetal adipose tissue proved to be comparable with our previously established sigmaPCB levels in mature breast milk of 93 Dutch women (median 414; range 158-969 ng/g of fat). The PCB congeneric distribution of fetal adipose tissue was not different from that of human milk. We conclude that maternal PCBs have a tendency to accumulate notably in fetal tissues with high triglyceride contents. They are easily transferred across the placenta and seem to become equilibrated among the apolar parts of maternal and fetal lipids.

We report on the PCB levels in plasma from 42-month-old children and the factors that determine these levels. We measured the levels of the PCB congeners 118 (2,4,5-3'4' pentachlorobiphenyl (CB)), 138 (2, 3,4-2'4'5'hexaCB), 153 (2,4,5-2'4'5'hexaCB), and 180 (2,3,4, 5-2'4'5'heptaCB) in cord plasma, breast milk, and plasma from 42-month-old children (n = 126) living in the Groningen area, The Netherlands. The sum of the levels of these four congeners was calculated for cord plasma (SigmaPCBcord), breast milk (SigmaPCBmilk), and 42-month plasma (SigmaPCB42mo). SigmaPCBcord was used as a measure of prenatal exposure. Postnatal exposure was assessed in terms of the SigmaPCBmilk and the duration of lactation. In addition, maternal factors including age, body weight and height, parity, and formal education were recorded. In 42-month-old children who have been fully breast-fed for at least six weeks as babies, the median SigmaPCB42mo was 4.5 times as high as that in formula-fed children (0.81 microg/L vs. 0.18 microg/L). The PCB levels in cord blood and human milk and the duration of breast-feeding predict the plasma PCB level at 42 months. Each additional week of full breast-feeding is estimated to result in an increase of 0.3% of the milk PCB level. We concluded that lactation is a major source for the child's PCB body burden at 42 months.

Adverse neurological effects of exposure to PCBs have been found up to 18 months of age. Now we report on the effect of pre- and postnatal exposure to PCBs and dioxins on the neurological condition at 42 months of age. For this purpose, PCB levels were determined in cord and maternal plasma, and used as a measure of prenatal exposure. Breast milk was analyzed for PCBs and dioxins. In addition, PCBs were determined in plasma sampled from the child at 42 months of age. We evaluated the neurological condition of 394 children using the Touwen/Hempel method. After adjustment for covariates, neither prenatal PCB exposure nor postnatal exposure to PCBs and dioxins was found to be related to the neurological condition at 42 months of age.

Objective: To investigate differences in the fatty acid composition, sterols, minor carbohydrates and sugar alcohols between human and formula milk., Design: We analyzed the concentrations of triglycerides, sterols, di- and monosaccharides and sugar alcohols, as well as the fatty acid composition of 10 currently available types of formula milk for term babies. Results were compared with mature human milk from 99 exclusively breast-feeding Dutch women, who collected 24-hour samples in the second week (n = 99), sixth week (n = 99) and 3 months (n = 25) after delivery. Infant formula milk data were considered different if they fell outside the mean +/- 2s.d. range of corresponding human milk data., Results: The triglyceride concentrations in human milk were lower than those of the formula milk, possibly due to an incomplete collection of fat-rich hindmilk. Formula milks tended towards a higher proportion of medium chain fatty acids and lower proportions of longer-chain polyunsaturated fatty acids. Formulas had cholesterol concentrations 3-35 times lower, and much higher phytosterol concentrations, compared with the human milk. In the formula milk types the glucose, sorbitol and myoinositol concentrations were generally lower, whereas the fucose and erythreitol concentrations were in the lower mean +/- 2s.d. human milk range. The galactose concentrations in the formulas were generally higher., Conclusions: Formula milk and human milk differ considerably in fatty acid composition and concentrations of cholesterol, phytosterols, monosaccharides and sugar alcohols. The biological consequences of these differences in composition are uncertain.

Numerous studies on infant nutrition show that breast-feeding has a beneficial effect on growth, morbidity, and neurological and cognitive functioning later in life. Moreover, there are indications that a relationship exists between the diet consumed during early childhood and morbidity in adulthood, such as atherosclerosis and insulin-dependent diabetes mellitus. The mechanism causing this advantageous effect of breast-feeding might be found in the fatty acid composition of human milk. The fatty acid content of formula milk is associated with biochemical parameters, cognitive development, and growth. Further research concentrating on randomized trials of 'fatty acid-enriched' formula milks is needed for the sake of children of mothers who opt for bottle-feeding.

The neurological optimality of 418 Dutch children was evaluated at the age of 18 months, in order to determine whether prenatal and breast milk mediated exposure to polychlorinated biphenyls (PCBs) and dioxins affected neurological development. Half of the infants were breast-fed, the other half were formula-fed. PCB concentrations in cord and maternal plasma were used as a measure of prenatal exposure to PCBs. To measure postnatal exposure, PCB and dioxin congeners were determined in human milk and in formula milk. After adjusting for covariates, transplacental PCB exposure was negatively related to the neurological condition at 18 months. Although greater amounts of PCBs and dioxins are transferred via nursing than via placental passage, an effect of lactational exposure to PCBs and dioxins could not be detected. We even found a beneficial effect of breast-feeding on the fluency of movements. We conclude that transplacental PCB passage has a small negative effect on the neurological condition in 18-month-old toddlers.

The presence of minor neurological dysfunction is associated with behavioural and cognitive development at school age. We have previously shown a relation between minor neurological dysfunction and perinatal disorders, especially abnormal neonatal neurological condition. We have now investigated the relation between breastfeeding and long-term neurological development. We studied 135 breastfed (for > or = 3 weeks) and 391 formula-fed children, born at term in the University Hospital Groningen between 1975 and 1979. A standard neonatal neurological examination was used to classify the infants as normal (247), slightly abnormal (213), or frankly abnormal (66). At 9 years of age the children were reexamined. In 1993 their mothers were asked to complete a questionnaire about how the children were fed as infants. After adjustment for obstetric, perinatal, neonatal neurological, and social differences, a small advantageous effect of breastfeeding on neurological status at 9 years of age was found (odds ratio for neurological non-normality 0.54 [95% CI 0.30-0.97]). Although a retrospective design cannot lead to definite conclusions, our data suggest a beneficial effect of breast-feeding on postnatal neurological development. Longer-chain polyunsaturated fatty acids, which are present in breast-milk but not in most formula-milks, may have a role since they are vital for brain development.