Comparison of Current Health, Functional Limitations, and Health Care Use of Young Adults Who Were Born With Extremely Low Birth Weight and Normal Birth Weight
OBJECTIVE. The objective of this study was to compare the current health status, physical ability, functional limitations, and health care use of extremely low birth weight and normal birth weight young adults.
METHODS. A longitudinal study was conducted of a population-based cohort of 166 extremely low birth weight survivors (501–1000 g birth weight; 1977–1982 births) and a group of 145 sociodemographically comparable normal birth weight individuals. Current health status, history of illnesses, hospitalizations, use of health resources, and physical self-efficacy were assessed through questionnaires that were administered to the young adults by masked interviewers.
RESULTS. Individuals completed the assessments at a mean age of 23 years. Neurosensory impairments were identified in 27% of extremely low birth weight and 2% of normal birth weight individuals. No differences were reported in the current health status for physical or mental summary scores. Extremely low birth weight young adults reported a higher prevalence of chronic health conditions in the past 6 months. A significantly higher proportion of extremely low birth weight individuals had functional limitations in seeing, hearing, and dexterity and experienced clumsiness and learning difficulties. Except for prescription glasses, medications for depression, and home-care services for extremely low birth weight individuals, there were no significant differences between groups in use of health care resources. Extremely low birth weight individuals had significantly weaker hand grip strength and lower scores for physical self-efficacy, perceived physical ability, and physical self-confidence.
CONCLUSIONS. Extremely low birth weight young adults seem to enjoy similar current health status to their normal birth weight peers. However, they continue to have significantly poorer physical abilities and a higher prevalence of chronic health conditions and functional limitations. Contrary to expectations, they do not pose a significant burden to the health care system at young adulthood.
Recent reports on the long-term outcomes of very low birth weight (VLBW) and extremely low birth weight (ELBW) infants who were born in the early post–neonatal intensive care era have moved beyond midchildhood and adolescence into young adulthood. At adolescence, most reports indicate that substantial morbidity persists in intellectual status, school achievements,1–3 behavioral difficulties,4 and lower growth attainment compared with the normal birth weight (NBW) group.5–7 Although there is some reduction in acute health care problems, the VLBW individuals have significantly higher rates of functional limitations, greater compensatory dependence, and increased use of health care resources.8,9
In the few studies that have pursued additional follow-up, many of the educational and growth disadvantages that are associated with being of ELBW and VLBW have persisted to adulthood.10–16 However, little is known of the functional limitations, health status, and health care needs of these vulnerable young adults (YAs) once they are too old to use pediatric services. Such information is necessary to project and plan for medical services beyond those that routinely are required by the general population at adulthood and middle age.
In this report, we present data at young adulthood on the general health, physical abilities, functional limitations, and health care use of a regional cohort of former ELBW infants who have been followed longitudinally from birth17 in comparison with a term-born NBW group.18 We hypothesized that although ELBW YAs would continue to have more chronic health problems, greater functional limitations, and poorer physical abilities than NBW YAs, there would be no differences in their current health status; furthermore, the absolute rates of use of health care services would decline even further than previously reported at adolescence.6
ELBW survivors (501–1000 g birth weight) who were born between 1977 and 1982 to residents of a geographically defined region in central-west Ontario were followed longitudinally from birth.17 We previously reported on their growth and health outcomes at age 8,18 in adolescence,6 and at young adulthood.16
At 8 years of age, term-born children (1977–1981 births) who were comparable in gender, age, and social class19 to the ELBW group were randomly recruited from a list that was provided by the local school boards and followed longitudinally.18
The YAs were the primary respondents for all questionnaires and were interviewed by lay professional interviewers who were unaware of the group status. The interview process involved a structured format using scripted questions with a skip pattern that was administered in the same order. The majority (93%) of interviews were conducted at McMaster Children's Hospital (Hamilton, Ontario, Canada) between January 1, 2002, and April 30, 2004. Information regarding health status and health care use of YAs with severe impairment was obtained from their parents.
Ethics approval was obtained from the Research Ethics Board of Hamilton Health Sciences, and written informed consent was obtained from all YAs and their parents.
Age, marital status, current living arrangements, household membership, educational attainment and employment were obtained from the YAs by direct interview. Parents provided information on their own education and current employment. Both maternal and paternal variables were included to assign parental socioeconomic status.19
General Health Information
The following standardized questionnaires were used:
SF-3620: A widely used and well-validated 36-item questionnaire measures physical and mental health in the previous 4 weeks across 8 domains. Physical health summary score is derived from 4 subscales: physical functioning (10 items that describe ability to do physical tasks), role—physical (4 items about difficulties or limitations in physical ability), bodily pain (2 items), and general health (5 items). Mental health summary score also has 4 subscales: vitality (4 items that measure energy level), social functioning (2 items regarding physical and mental health interfering with normal social life), role—emotional (3 items about effect of mental problems on everyday life), and mental health (5 items that measure mood). Scores were converted to norm-based scores (mean: 50; SD: 10). In addition, respondents were asked to rate their health in 1 of the following categories: excellent, very good, good, fair, or poor.
Ontario Child Health Study Questionnaire21: Provides information on chronic health conditions, functional limitations, and emotional and mental health issues (diagnosed by a health professional and lasting 6 months or longer); absenteeism at work or at school as a result of chronic health problems; and limitations in normal activities as a result of health problems.
Canadian Community Health Survey (Statistics Canada)22–24: Data from cycles 2.1 (2003) and 3.1 (2005) on the health of YAs (aged 20–24) are presented as footnotes in the tables where relevant information is available.
Physical Self-Efficacy Scale
The Physical Self-Efficacy Scale25 is a self-administered questionnaire that provides information on total physical self-efficacy, perceived physical ability, and physical self-presentation confidence.
Hand-grip strength was measured independently in both hands using a dynamometer. Data are presented for dominant hand for participants without neurosensory impairments (NSI).
Use of Health Care Resources
The questionnaire was based on several sources.26,27 The information included visits to all health professionals, outpatient tests, and use of home-care services in the past 6 months and hospitalizations and surgery in the past 12 months. All medications that were taken on a regular basis (and reasons for taking) were noted. Use of mechanical aids or assistive devices and home/car/house adaptations, etc, were also recorded.
χ2 tests of significance were used to test differences in categorical variables between groups (ELBW versus NBW) and gender-specific differences. Fisher's exact test was used when necessary. For variables with significant differences, analysis of variance to compare mean differences between groups and odds ratios (ORs) and 95% confidence intervals (CI) were calculated. T tests were used to compare mean values. Although exact P values are provided where applicable, because of multiple testing, Holm's correction28 was applied to all P < .05 separately for each table (for total group and by gender) to establish statistical significance. Values that were found to be significant by Holm's correction are indicated with a superscript Holm's beside the P values. SPSS11.0 (SPSS, Chicago, IL) was used for all statistical analyses.
Of 397 livebirths, 179 (45%) survived to hospital discharge17; 13 children subsequently died: 6 before 3 years of age, 4 with severe NSI between 9 and 16 years, and 3 in the late teens (1 NSI). Of 166 individuals available, 9 were lost and 8 refused (6 of these 17 had NSI). The outcome is reported on 149 (90%) of 166 ELBW YAs, including 7 with severe NSI for whom parental proxy responses were obtained.
Of the 145 term control subjects,18 5 were lost to follow-up, 7 refused (none had NSI), and the remaining 133 (92%) participated.
Birth Characteristics and Sociodemographics of Parents and YAs
Mean birth weight for the ELBW cohort was 841 g (SD: 124 g), and mean gestational age was 27.1 (SD: 2.3) weeks (Table 1). More than one quarter of ELBW individuals were <750 g (27%), 22% were <26 weeks, and 24% were small for gestational age.29 Mean duration of hospitalization was 101 (SD: 32) days. Both cohorts predominantly were white (>94%) and from 2-parent families (>79%), and approximately half were from the upper 2 socioeconomic levels.19 Highest educational achievement did not differ between cohorts. Mean age at assessment was 23.3 years (SD: 1.2 years) for ELBW and 23.6 years (SD: 1.1 years) for NBW (P = .02).
Current General Health
There were no significant differences by group among the 8 scales of SF-36, except that ELBW individuals scored lower on mental health (P = .04) and ELBW male individuals had lower scores than NBW male individuals for physical functioning scale (P = .04; Table 2). None of the group × gender interactions was significant. There were no differences by group or by gender in the SF-36 summary scores for physical or mental health. However, when asked to rate their health in 1 of 5 categories (excellent, very good, good, fair, or poor), statistically significant differences were found by group (P = .03) and among male individuals (P = .04), with ELBW individuals reporting their health less favorably than NBW individuals (and Canadian data22). These differences became nonsignificant when YAs with NSI were excluded.
Chronic Health Conditions
ELBW YAs had a higher prevalence of NSI (27% vs 2%; P < .001Holm's) and were more likely to have multiple (≥2) impairments (10% vs 0%; P = .0004Holm's; Table 3). Differences in chronic physical conditions (ELBW versus NBW) were present for the following: seizures (8% vs 2%; OR: 3.8; 95% CI: 1.0–13.7; P = .03), asthma (male individuals only; 18% vs 3%; OR: 6.3; 95% CI: 1.3–29.5; P = .009), and recurrent bronchitis (6% vs 1%; OR: 8.5; 95% CI: 1.0–67.9; P = .02). The proportion of ELBW individuals with asthma by group and gender is higher than the Canadian data23 (see Table 3, footnote i). There were no differences in emotional problems and mental illness between groups.
When chronic physical health problems were aggregated, ELBW YAs differed significantly from NBW YAs: a lower proportion had no problems, and a higher proportion had ≥3 problems (P = .01). Similar differences were seen in male individuals (P < .001Holm's) but not in female individuals (P = .89). However, when participants with NSI were excluded, these differences no longer were significant for the overall group or for female individuals, but differences among male individuals remained significant (P = .001). Among those who had at least 1 chronic condition, the mean number per individual was 2.8 (SD: 1.9) for ELBW versus 2.2 (SD: 0.14) for NBW (P = .01).
Self-report of injuries in the past 12 months, serious enough to limit normal activities, did not differ between groups (ELBW 24% vs NBW 22%; P = .71). However, both groups reported slightly higher rates than the general Canadian population (18%, aged 20–24).23
Late Retinal Detachment
In eliciting details of types of surgeries, we unexpectedly found that 6 ELBW YAs (4%) experienced sudden late retinal detachment, with 2 YAs remaining blind in the affected eye after laser surgery. Voluntary ophthalmologic assessments on 45 ELBW YAs yielded 3 additional cases of retinal tears that also required surgery. None of the NBW YAs experienced the same.
Current Functional Limitations
ELBW YAs reported significantly more functional limitations than NBW YAs by group and by gender for the following variables (Table 4): difficulty seeing (group P < .001Holm's, male P = .002Holm's, female P < .001Holm's), bilateral blindness (group P = .001Holm's, female P = .01), clumsiness (group P = .001Holm's; male P = .007, female P = .02), dexterity (P = .002Holm's; male P = .02, female P = .02), and learning disabilities (group P < .001Holm's, male P = .003, female P < .001Holm's). In addition, there were differences by group (P = .04) but not by gender for hearing difficulties and reduced self-care abilities (P = .03). These results include 7 parental proxy responses.
When functional limitations were summed and compared by categories of none, 1 to 2 and ≥3, ELBW individuals were less likely to have no limitations and more likely to have multiple limitations. These differences were significant by group (P < .001Holm's) and by gender (P < .001Holm's) and remained significant when NSI were excluded.
More ELBW than NBW YAs reported limitations in carrying out “normal daily activities” as a result of health problems (21% vs 11%; OR: 2.1; 95% CI: 1.0–4.0; P = .03, NS by gender; corresponding Canadian data 19.1%23). These differences became NS when individuals with NSI were excluded. Among those with limitations, there were significant differences between groups in the reasons for limitations (P = .00004, data not shown): a significant majority (81%) of ELBW individuals cited mental illness and NSI as the main reasons, whereas a similar proportion (80%) of NBW individuals identified chronic conditions and acute injuries.
There were no significant differences by group (ELBW versus NBW: 24% vs 19%) or by gender (male: 16% vs 13%; female: 30% vs 23%) in the proportion with any absenteeism from school/work as a result of illness during the previous month. The proportions with absenteeism are similar to the Canadian data (male: 14.7%; female: 22.2%; total: 18.3%).23 However, significant differences were noted for mean number of days absent among female individuals (ELBW: 5.5 days [SD: 6.3 days]; NBW: 2.6 days [SD: 2.2 days]; P = .04, data not shown).
Health Care Use
There were no significant differences by group or by gender for the proportion with overnight hospitalizations or surgery in the past 12 months (Table 5). During the past 6 months, there were no differences in the proportion with visits to the emergency department or visits to any health professionals by group or by gender, with the exception of social worker contacts by ELBW female individuals (13% vs 4%; P = .04). The proportion who had outpatient investigations did not differ by group or by gender.
The use of prescription drugs differed significantly by group only for medications for depression (ELBW 14% vs NBW 6%; OR: 2.6; 95% CI: 1.0–6.0; P = .025) but not by gender. In terms of assistive devices/aids, there were no significant differences in the use of braces, crutches, or canes between groups, although the reasons for their use differed: ELBW individuals had chronic conditions related to NSI, whereas NBW individuals had acute injuries. Four ELBW and 1 NBW YA required wheelchairs, whereas none of the NBW individuals did (P = .43); and prescription glasses were required more often by ELBW YAs (64% vs 37%; OR: 3.1; 95% CI: 1.9–5.0; P < .001Holm's; male P = .002, female P < .001Holm's). In addition, a higher proportion of ELBW individuals required visual aids such as Braille equipment and canes (group P = .002Holm's; female P = .003Holm's). Very few participants wore hearing aids (2 female ELBW and 1 female NBW), despite more who reported “hearing problems.”
Although a minority of individuals required home-care services, there were significant differences between groups (8% vs 2%; OR: 5.7; 95% CI: 1.2–26.1; P = .01). Significantly more ELBW than NBW YAs received services such as household help, specialized companionship, and personal care (7% vs 1%; OR: 9.5; 95% CI: 2.0–39.5; P = .009). One ELBW female individual with severe impairment required episodic respite care, and another ELBW female individual was in permanent foster care.
Physical Self-Efficacy, Physical Activity, and Hand-Grip Strength
ELBW YAs had significantly lower total scores in the physical self-efficacy scale (P < .001Holm's) and in the 2 subscales of perceived physical ability (P < .001Holm's) by group and by gender and in physical self-presentation confidence by group (P = .001Holm's) and by female gender (P = .002Holm's; Table 6). These differences persisted even when individuals with NSI were excluded.
A significantly lower proportion of ELBW versus NBW YAs reported regular participation in sports and strenuous activities (38% vs 59%; P = .001Holm's), and the proportion also was lower in comparison with Canadian data (60.2%; see Table 6, footnote d).23 A higher proportion of ELBW individuals attributed the lower participation rates to health conditions (22% vs 9%; P = .004Holm's). However, although differences were observed among male individuals (P < .001Holm's), there were no significant differences in the proportion of female individuals who participated and those who were unable to participate as a result of health conditions. The differences between groups in participation rate remained significant after NSI were excluded (P = .02).
Despite exclusion of those with NSI, ELBW YAs had significantly lower hand-grip strength in their dominant hand compared with NBW YAs (32 [SD: 10] vs 38 [SD: 10]; P < .001Holm's) and by gender (male P = .002Holm's; female P < .001Holm's). The analysis of variance was significant for group (P < .001) and gender (P < .001), but there was no interaction.
The findings of this study confirm our hypotheses that by the time ELBW survivors reach adulthood, their current physical and mental health is similar to that of NBW YAs for overall group and by gender. Except for a higher prevalence of NSI, differences were observed in only a few residual chronic health conditions, such as seizures, recurrent bronchitis, and asthma (male individuals). Although still significantly different, both groups had a relatively low proportion without any chronic conditions. The mean number of chronic conditions per individual remained significantly higher for ELBW than for NBW individuals. ELBW YAs also had higher rates of functional limitations, mainly in visual deficits and dexterity, and of clumsiness and learning difficulties, and a minority had reduced self-care abilities and hearing problems. These limitations remained significant when YAs with NSI were excluded. Twice as many ELBW versus NBW YAs reported limitations in daily activities related to health problems, but these differences were attributed mainly to those with NSI. It is important to reiterate that although ELBW participants had a higher prevalence of chronic conditions and functional limitations, the NBW group was not without significant difficulties. These results underscore the importance of a comparison group to place the findings in perspective.
Cooke et al13 found no significant differences in health status between mainstream 20-year-old British VLBW and NBW YAs, except for lower physical functioning score (SF-36) and lower general health perception by male VLBW YAs. Unfortunately, the response rate in this study was only 50%. Hack et al11 reported higher rates of chronic health conditions (33% vs 21%) and multiple conditions among Cleveland VLBW versus NBW YAs. However, with the exception of those with NSI, the health status of VLBW YAs was equivalent to that of NBW control subjects. Similar findings were reported by Ericson and Källen10 in VLBW male individuals. A few studies reported higher rates of asthma and use of inhalers13,30 and some residual effects on respiratory function.30,31
Remarkably, we found no differences in use of health care resources at young adulthood, in terms of acute illnesses, hospitalizations, surgical procedures, and visits to specialists. There also were no differences in the use of rehabilitative services, such as occupational therapists, physiotherapists, and speech pathologists. Use of prescription medications was similar in both groups, except for medications for depression. Assistive devices such as wheelchairs were limited to those with NSI, and a similar proportion of both cohorts used braces and crutches, usually for acute injuries in the case of NBW YAs. A minority of ELBW YAs required home-care services for personal care and household help, foster care, and temporary respite care.
The most frequent compensatory aid that was used by ELBW was prescription glasses. The high prevalence of visual problems at young adulthood also was reported by Hack et al11 and Ericson.10 However, of particular concern in our study were the high rates of late retinal detachment (4%), which seem to have occurred in our study participants (born before the cryotherapy era), since the last assessment at adolescence. The discovery of 3 additional individuals with asymptomatic retinal tears among 45 YAs who volunteered to be tested lead us to believe that there may be other undetected cases. Similarly, the 15-year outcome study of the Cryotherapy for Retinopathy of Prematurity trial for threshold retinopathy32 found retinal detachment in 4.5% of treated eyes and 7.7% of control eyes. What is worrisome is that these events occurred in eyes that were judged to be normal at the 10-year assessment. The development of these adverse outcomes indicates the need for lifelong follow-up of people with a history of retinopathy.32
There are no available reports in the literature for comparison with our study regarding use of health care resources by ELBW individuals at young adulthood. Direct comparison with our same cohort at adolescence6 was not possible because the respondents in the last study were parents and the time frame was in the past 2 years. The respondents this time were the YAs, and for reasons of recall bias, the period of inquiry was only for the last 6 to 12 months. We are aware of differences in perceptions regarding health conditions between parents and children,4,9,33 but whether there also are differences in responses related to health care use is not known. It is possible that the lack of significant differences in this study may be a reflection of the overall low base rates of health care use at this age. It is clear that the costs to the health care system and other services that are associated with extreme prematurity are substantial in the early years and persist into midchildhood.34,35 Thereafter, we have shown that there is a significant decline in use of health services around adolescence6 and beyond. Contrary to the earlier pessimistic projections,36 ELBW YAs do not pose a considerable lifelong burden to the health care system. Economic evaluation is in progress.
Consistent with this study, several investigators9–11 reported that VLBW adolescents and YAs lead a less active physical lifestyle and have limited participation in sports and strenuous activities. A reduction in muscle strength and physical working capacity among VLBW boys was reported by Ericson et al.10 Rogers et al37 found that 17-year-old unimpaired ELBW survivors had significantly lower motor performance than control subjects in aerobic capacity, strength, endurance, flexibility, and activity level. They speculated whether the lower scores on these measures were a result of extreme prematurity (subclinical pulmonary compromise or subtle neuromotor difficulties) or possible sheltering by parents38 or reflected a preference by the ELBW individuals for a lower physically active lifestyle. However, we and others have reported that ELBW children are consistently described by their parents as having problems with clumsiness and coordination,6,37,39 which also were acknowledged by the ELBW YAs themselves in this study. In addition, they rated themselves lower in perceived physical ability and physical self-presentation confidence and were found to have lower hand-grip strength. Overall, a lower proportion of ELBW YAs participated in regular physical activities in comparison with NBW YAs and the Canadian national norms.22
This is the first longitudinal study of the health status, chronic conditions, physical abilities, and health care use at young adulthood for ELBW survivors who were born in the early era of neonatal intensive care. These data were derived from a defined geographic region with high participation rates, include a control group, and were collected by experienced interviewers who were masked to the group status. We acknowledge that there may be recall bias inherent in self-reported data among both groups, which were not corroborated by physician or hospital charts. Furthermore, although this is the largest study to date on health outcomes at young adulthood, the number of subjects in epidemiologic terms is relatively small. It is possible that we may have been underpowered to detect differences in some outcomes. Nevertheless, the findings for ELBW YAs are optimistic in terms of a reasonably good current health status and a significant decline in use of health care resources. However, as anticipated, ELBW YAs continue to suffer from chronic health conditions, and a significantly higher proportion have functional limitations. For various reasons, ELBW YAs seem to lead a more sedentary lifestyle than their peers. Additional follow-up to late adulthood is essential to determine whether the chronic health conditions and functional limitations among ELBW YAs will get progressively worse with age and whether they will have a higher prevalence of cardiovascular disease and metabolic problems in the future.40–45 Finally, although these data may not be entirely generalizable to the current, even smaller survivors of neonatal intensive care, they provide some guidelines to health care providers and funding agencies for projection, planning, and allocation of the necessary resources for future at-risk infants.
This study was supported by grants MOP42536 from the Canadian Institutes of Health Research and 1 RO1 HD40219 from the National Institute of Child Health and Human Development.
We thank the ELBW and NBW YAs and their parents for cooperation with our many studies. We also thank our research staff Liz Merz (for tracing the participants), Lorraine Hoult and Mary Lou Schmuck (for statistical analysis), and Diane Turcotte (for typing the manuscript). We appreciate the support of the department of Pediatrics and the Children's Hospital, McMaster University (Hamilton, ON, Canada).
- Accepted September 26, 2006.
- Address correspondence to Saroj Saigal, MD, McMaster University, Department of Pediatrics, 1200 Main St W, Room 4G40, Hamilton, Ontario, Canada L8N 3Z5. E-mail:
The authors have indicated they have no financial relationships relevant to this article to disclose.
- ↵Saigal S, Hoult LA, Streiner DL, Stoskopf BL, Rosenbaum PL. School difficulties at adolescence in a regional cohort of children who were extremely low birth weight. Pediatrics.2000;105 :325– 331
- ↵Saigal S, Pinelli J, Hoult L, Kim MM, Boyle M. Psychopathology and social competencies of adolescents who were extremely low birth weight. Pediatrics.2003;111 :969– 975
- ↵Saigal S, Stoskopf BL, Streiner DL, Burrows E. Physical growth and current health status of infants who were of extremely low birth weight and controls at adolescence. Pediatrics.2001;108 :407– 415
- ↵Hack M, Taylor HG, Klein N, Mercuri-Minich N. Functional limitations and special health care needs of 10- to 14-year-old children weighing less than 750 grams at birth. Pediatrics.2000;106 :554– 560
- ↵Johnson A, Bowler U, Yudkin P, et al. Health and school performance of teenagers born before 29 weeks gestation. Arch Dis Child Fetal Neonatal Ed.2003;88 :F190– F198
- ↵Ericson A, Källén B. Very low birthweight boys at the age of 19. Arch Dis Child Fetal Neonatal Ed.1998;78 :F171– F174
- Hack M, Schluchter M, Cartar L, Rahman M, Cuttler L, Borawski E. Growth of very low birth weight infants at age 20 years. Pediatrics.2003;112(1) . Available at: www.pediatrics.org/cgi/content/full/112/1/e30
- ↵Cooke RW. Health, lifestyle, and quality of life for young adults born very preterm. Arch Dis Child.2004;89 :201– 206
- Doyle LW, Faber B, Callanan C, Ford GW, Davis NM. Extremely low birth weight and body size in early adulthood. Arch Dis Child.2004;89 :347– 350
- ↵Saigal S, Rosenbaum P, Hattersley B, Milner R. Decreased disability rate among 3-year-old survivors weighing 501 to 1000 grams at birth and born to residents of a geographically defined region from 1981 to 1984 compared with 1977 to 1980. J Pediatr.1989;114 :839– 846
- ↵Hollingshead AS. Four Factor Index of Social Status. New Haven, CT: Yale University; 1975
- ↵Ware JE, Kosinski M. SF-36 Physical and Mental Health Summary Scales: A Manual for Users of Version 1. 2nd ed. Lincoln, RI: QualityMetric Inc; 2001
- ↵Statistics Canada. Canadian Community Health Survey (CCHS 3.1), 2005: Community Belonging and Self-Perceived Health— Early CCHS Findings. Catalogue No. 82-621. Vol 2006. No. 1. Ottawa, Ontario, Canada: Statistics Canada; 2006
- ↵Statistics Canada. Canadian Community Health Survey (CCHS 3.1), 2005: Health Indices. Catalogue No. 82-221. Vol 2006. No. 1. Ottawa, Ontario, Canada: Statistics Canada; 2006
- ↵Browne G, Gafni A, Roberts J, Goldsmith A, Jamieson E. Approach to the Measurement of Costs (Expenditures) When Evaluating Health and Social Programmes. Health and Social Service Utilization. System-Linked Research Unit [Working Paper 95-11]. Hamilton, Ontario, Canada: McMaster University; 1995
- ↵Cohen SB. Sample Design of the 1997 Medical Expenditure Panel Survey, Household Component. Rockville, MD: US Department of Health and Human Services, Public Health Service, Agency for Healthcare Research and Quality; 2000
- ↵Kramer MS, Platt RW, Wen SW, et al. Fetal/Infant Healthy Study Group of the Canadian Perinatal Surveillance System 2001. A new and improved population-based Canadian reference for birth weight for gestational age. Pediatrics2001;108(2) . Available at: www.pediatrics.org/cgi/content/full/108/2/e35
- ↵Doyle LW, Olinsky A, Faber B, Callanan C. Adverse effects of smoking on respiratory function in young adults born weighing less than 1000 grams. Pediatrics.2003;112 :565– 569
- ↵Rogers M, Fay TB, Whitfield MF, Tomlinson J, Grunau RE. Aerobic capacity, strength, flexibility, and activity level in unimpaired extremely low birth weight (≤800 g) survivors at 17 years of age compared with term-born control subjects. Pediatrics.2005;116(1) . Available at: www.pediatrics.org/cgi/content/full/116/1/e58
- ↵Jongmans M, Mercuri E, de Vries L, Dubowitz L, Henderson SE. Minor neurological signs and perceptual-motor difficulties in prematurely born children. Arch Dis Child Fetal Neonatal Ed.1997;76 :F9– F14
- ↵Barker DJ, Bull AR, Osmond C, Simmonds SJ. Fetal and placental size and risk of hypertension in adult life. BMJ.1990;301 :259– 262
- Finken MY, Keijzer-Veen MG, Dekker FW, et al, on behalf of the Dutch POPS-19 Collaborative Study Group. Preterm birth and later insulin resistance: effects of birth weight and postnatal growth in a population based longitudinal study from birth to adult life Insulin resistance 19 years after preterm birth. Diabetologia.2006;49 :478– 485
- Euser AM, Finken MJ, Keijzer-Veen MG, Hille ET, Wit JM, Dekker FW; the Dutch POPS-10 Collaborative Study Group. Associations between prenatal and infancy weight gain and BMI, fat mass, and fat distribution in young adulthood: a prospective cohort study in males and females born very preterm. Am J Clin Nutr.2005;81 :480– 487
- ↵Singhal A, Wells J, Cole TJ, Fewtrell M, Lucas A. Programming of lean body mass: a link between birth weight, obesity, and cardiovascular disease? Am J Clin Nutr.2003;77 :726– 730
- Copyright © 2007 by the American Academy of Pediatrics