Sonja Strang-Karlsson

Very Low Birth Weight and Behavioral Symptoms of Attention Deficit Hyperactivity Disorder in Young Adulthood: The Helsinki Study of Very-Low-Birth-Weight Adults

OBJECTIVE Children with very low birth weight (<1500 g) are at increased risk for attention deficit hyperactivity disorder (ADHD). Whether this increased risk continues into adulthood is unknown. The authors assessed behavioral symptoms of ADHD in a well-characterized cohort of very-low-birth-weight young adults who were either small for gestational age (less than two standard deviations below the Finnish mean) or appropriate for gestational age (within two standard deviations of the mean). METHOD A total of 162 very-low-birth-weight subjects (small for gestational age: N=52; appropriate for gestational age: N=110) and 172 term comparison subjects 18 to 27 years of age completed the Adult Problem Questionnaire, which yielded six exploratory factor analysis-derived subscales. Participants were also asked about substance use. RESULTS Very-low-birth-weight adults in the small for gestational age subgroup scored higher on the executive dysfunctioning and emotional instability subscales of the Adult Problem Questionnaire than did those in the appropriate for gestational age subgroup and the comparison group. The appropriate for gestational age and comparison groups had similar scores on these subscales. On the alcohol use subscale of the Adult Problem Questionnaire, both the appropriate and small for gestational age subgroups scored lower than comparison subjects and also reported fewer risk-taking behaviors (alcohol, smoking, and use of recreational drugs) than did comparison subjects. CONCLUSIONS Rather than very low birth weight per se, intrauterine growth retardation, as reflected by small for gestational age status in the very-low-birth-weight subjects, confers a risk for behavioral and emotional adversity related to ADHD in young adulthood.

Decreased bone mineral density in adults born with very low birth weight: a cohort study.

Petteri Hovi and colleagues evaluate skeletal health in 144 adults born preterm with very low birth weight and show that as adults these individuals have significantly lower bone mineral density than do their term-born peers.

Very Low Birth Weight Increases Risk for Sleep-Disordered Breathing in Young Adulthood: The Helsinki Study of Very Low Birth Weight Adults

OBJECTIVE. We investigated whether very low birth weight (<1500 g) is associated with the risk of sleep-disordered breathing in young adulthood. METHODS. The study was a retrospective longitudinal study of 158 young adults born with very low birth weight and 169 term-born control subjects (aged 18.5–27.1 years). The principal outcome variable was sleep-disordered breathing defined as chronic snoring. RESULTS. The crude prevalence of chronic snoring was similar in both groups: 15.8% for the very low birth weight group versus 13.6% for the control group. However, after controlling for the confounding variables in multivariate logistic regression models (age, gender, current smoking, parental education, height, BMI, and depression), chronic snoring was 2.2 times more likely in the very low birth weight group compared with the control group. In addition, maternal smoking during pregnancy was significantly and independently of very low birth weight related to risk of sleep-disordered breathing. Maternal preeclampsia, standardized birth weight, and, for very low birth weight infants, small-for-gestational-age status were not related to sleep-disordered breathing. CONCLUSIONS. Premature infants with very low birth weight have a twofold risk of sleep-disordered breathing as young adults. In addition, maternal smoking during pregnancy increases the risk of sleep-disordered breathing by more than twofold.

Ambulatory Blood Pressure in Young Adults with Very Low Birth Weight

OBJECTIVE We hypothesized that, as compared with a matched control group born at term, young adults with very low birth weight (VLBW <1.5 kg) would have higher 24-hour ambulatory blood pressure. STUDY DESIGN We studied 118 18- to 27-year-old subjects born with VLBW within the greater Helsinki area and 120 term-born control subjects with similar age, sex, and birth hospital. The mean birth weight for VLBW subjects was 1.1 kg (standard deviation [SD], 0.2) and for controls, 3.6 kg (SD, 0.5). Gestational ages were 29.2 (SD, 2.3) and 40.1 (SD, 1.0) weeks. Current education of higher-educated parents served as an indicator of childhood socioeconomic status. Ambulatory blood pressure was measured during a 24-hour period with an oscillometric device (Spacelabs 90207). RESULTS VLBW subjects had, with sex, age, and body mass index adjustment, a 2.4 mm Hg (95% confidence interval, 0.2 to 4.6) higher 24-hour systolic pressure. We found hypertension in 11 VLBW subjects and in 3 term-born subjects, giving an adjusted odds ratio of 4.0 (1.1 to 14.8). When socioeconomic status was taken into account, results remained unchanged. CONCLUSIONS Higher rates of hypertension and higher 24-hour blood pressure among young adults with VLBW may indicate higher risk for adverse cardiovascular outcomes.

Neurocognitive abilities in young adults with very low birth weight

Objective: Although severely preterm birth has been associated with impaired neurocognitive abilities in children, follow-up studies in adulthood are scarce. We set out to study whether adults born with very low birth weight (VLBW) (<1,500 g), either small for gestational age (SGA) (birth weight ≤−2 SD) or appropriate for gestational age (AGA), differ in a range of neurocognitive abilities and academic performance from adults born at term and not SGA. Methods: As part of the Helsinki Study of Very Low Birth Weight Adults, 103 VLBW (37 SGA) and 105 term-born control adults (mean age 25.0, range 21.4–29.7 years) without major neurosensory impairments participated in the follow-up study in 2007–2008. The test battery included measures of general cognitive ability as well as executive functioning and related abilities. Academic performance was self-reported. Results: With adjustment for sex and age, the VLBW group scored lower or performed slower than the control group in some indices of all tests (these mean differences ranged from 0.3 to 0.5 SD units, p ≤ 0.03) and they had received remedial education at school more frequently; however, no differences existed in self-reported academic performance. The differences were evident in both VLBW-SGA and VLBW-AGA groups. Further covariate adjustments for parental education, current head circumference, and head circumference at birth and, in tests of executive functioning and related abilities, adjustment for IQ estimate had minor effects on the results. Conclusions: In comparison with control adults, VLBW adults scored lower on several neurocognitive tests. Poorer neurocognitive performance is associated with VLBW irrespective of the intrauterine growth pattern.

Slower Reaction Times and Impaired Learning in Young Adults With Birth Weight <1500 g

OBJECTIVE: Children with very low birth weight (VLBW; <1500 g) perform worse on cognitive tests than do children who are born at term. Whether this difference persists into adulthood has been little studied. We assessed core neurocognitive abilities (processing speed, working memory, attention, and learning capacity) in young adults with VLBW and in term-born control subjects. METHODS: In conjunction with the Helsinki Study of Very Low Birth Weight Adults, 147 VLBW and 171 control subjects who were aged 18 to 27 years and did not have neurosensory impairments performed a computerized test battery (CogState Ltd, Melbourne, Australia). T tests and linear regression models were used. Cohens d was used to express effect size (ES). RESULTS: VLBW adults had slower reaction times than did control subjects on all 5 tasks: simple reaction time (mean difference: 4.0% [95% confidence interval (CI): 1.1%–7.0%]; ES: 0.30), choice reaction time (mean difference: 3.2% [95% CI: 0.3%–6.2%]; ES: 0.24), working memory (mean difference: 8.4% [95% CI: 3.7%–13.4%]; ES: 0.40), divided attention (mean difference: 7.2% [95% CI: 2.7%–11.9%]; ES: 0.36), and associated learning reaction time (mean difference: 6.4% [95% CI: 1.3%–11.9%]; ES: 0.28). In addition, VLBW adults showed impaired learning abilities on the associated learning task (percentage of correct responses: 85.7 vs 80.2; P < .001; ES: 0.64). The results were little affected by adjustment for confounders. CONCLUSIONS: Nonimpaired VLBW individuals exhibited slower psychomotor speed and lower accuracy on the associated learning task. These results indicate that very preterm birth, even when obvious neurosensory deficits are absent, may have long-term consequences on core neurocognitive abilities.

Advanced Pubertal Growth Spurt in Subjects Born Preterm: The Helsinki Study of Very Low Birth Weight Adults

CONTEXT Among people born at term, low birth weight is associated with early puberty. Early maturation may be on the pathway linking low birth weight with cardiovascular disease and type 2 diabetes. Subjects born preterm with very low birth weight (VLBW; <1500 g) have as adults increased risk factors for cardiovascular disease. Little is known about their pubertal timing. OBJECTIVE The objective of the investigation was to study the timing of pubertal growth in subjects born preterm with VLBW as compared with controls. DESIGN, SETTING, AND PARTICIPANTS A follow-up study of subjects born preterm including 188 VLBW and 190 term-born control subjects. Growth data were available for 128 VLBW and 147 control subjects, of whom we excluded 15 and 1, respectively, because of neurological impairment. MAIN OUTCOME MEASURE Timing of pubertal growth spurt was estimated by assessing the ages, corrected for gestational age at birth, at acceleration (take-off) and peak height velocity of pubertal growth, and age at attaining adult height. RESULTS All components of pubertal growth occurred earlier in VLBW subjects than in controls. Age at take-off was 0.8 yr earlier [95% confidence interval (CI) 0.4-1.3] in VLBW subjects born appropriate and 0.9 yr earlier (95% CI 0.4-1.5) in those born small for gestational age. VLBW subjects were more likely to have a pubertal growth spurt that was at least 2 yr earlier than population average [odds ratio 3.8 (95% CI: 1.5-9.6)]. CONCLUSIONS Prematurity per se is associated with advanced pubertal growth. Advanced puberty may be among the factors mediating adult metabolic outcomes in subjects born preterm with VLBW.

Lower conditioning leisure-time physical activity in young adults born preterm at very low birth weight.

Background Adults born preterm at very low birth weight (VLBW, <1500 g) have elevated levels of risk factors for cardiovascular diseases and type 2 diabetes. Preliminary observations suggest that this could partly be explained by lower rates of physical activity. The aim of this study was to assess physical activity in healthy young adults born preterm at very low birth weight compared with term-born controls. Methodology/Principal Findings We studied 94 unimpaired young adults, aged 21–29 years, born at VLBW and 101 age-, sex-, and birth hospital-matched term-born controls from one regional center in Southern Finland. The participants completed a validated 30-item 12-month physical activity questionnaire and the NEO-Personality Inventory based on the Big Five taxonomy, the most commonly used classification of personality traits. Yearly frequency, total time, total volume and energy expenditure of conditioning and non-conditioning leisure-time physical activity (LTPA) and commuting physical activity were compared between VLBW and term-born subjects. A subset of participants underwent dual-energy x-ray absorptiometry for body composition measurement. Data were analyzed by multiple linear regression. Compared with controls, VLBW participants had lower frequency [−38.5% (95% CI; −58.9, −7.7)], total time [−47.4% (95% CI; −71.2, −4.1)], total volume [−44.3% (95% CI; −65.8, −9.2)] and energy expenditure [−55.9% (95% CI; −78.6, −9.4)] of conditioning LTPA when adjusted for age, sex, body mass index, smoking, parental education and personality traits. Adjusting for lean body mass instead of body mass index attenuated the difference. There were no differences in non-conditioning LTPA or commuting physical activity. Conclusions/Significance Compared with term-born controls, unimpaired VLBW adults undertake less frequent LTPA with lower total time and volume of exercise resulting in lower energy expenditure. Differences in personality that exist between the VLBW and term-born groups do not seem to explain this association.

Intima-Media Thickness and Flow-Mediated Dilatation in the Helsinki Study of Very Low Birth Weight Adults

BACKGROUND: Adults born at a very low birth weight (VLBW) (< 1500 g), compared with those born at term, bear risk factors for cardiovascular disease, including higher blood pressure and insulin resistance. OBJECTIVE: We studied, in young adults born at a VLBW, early signs of an accelerated atherosclerotic process and the relationship of these signs with postnatal growth. METHODS: We compared 92 with a VLBW with 68 who were born at term. At age 18 to 27, we measured stiffness and intima-media thickness (IMT) of the right carotid artery and flow-mediated dilatation (FMD) of the right brachial artery. RESULTS: Those with a VLBW had 1.1% units higher FMD (95% confidence interval [CI]: 0.0–2.2) (P = .06) and 0.5% units higher IMT relative to lumen size (95% CI: 0.1–0.9). IMT or FMD, when analyzed as the absolute change in millimeters, and carotid stiffness in the groups were similar. Among those with a VLBW, each 100-g-greater weight gain during the first 2 postnatal weeks predicted 1.1% units higher FMD (95% CI: 0.2–2.0) in adulthood. CONCLUSIONS: Although young adults born at VLBWs, compared with those born at term, have higher levels of risk factors for cardiovascular disease, we found no clear evidence for elevated early markers of atherosclerosis. However, in relation to artery lumen diameter, IMT in the participants who had a VLBW was higher than in those who were born at term. In our study, weight gain during the first postnatal weeks had no harmful effect on the arteries in young adulthood.

Preterm birth reduces the incidence of atopy in adulthood

BACKGROUND Immunologic pathways are primed in early life. Preterm birth can influence this process and thereby affect whether a person will have atopy later in life. Previous studies on the effects of preterm birth on atopy in adulthood have been inconclusive and limited to children or subjects born moderately preterm. OBJECTIVE Our aim was to compare the incidence of atopy among young adults who were born preterm and at very low birth weight (≤ 1500 g) with that of term-born young adults (control subjects). METHODS The study comprised 166 adults who were born preterm and at very low birth weight and 172 control subjects, all of whom were from the Helsinki Study of Very Low Birth Weight Adults. We assessed atopic predisposition at ages 18 to 27 years using skin prick tests for 6 common aeroallergens and measurements of serum concentrations of total IgE and 3 types of allergen-specific (cat, birch, and timothy) IgE. We asked the subjects whether they had been given a diagnosis of asthma or allergic rhinitis or had atopic eczema and analyzed data by using logistic or linear regression, adjusting for potential confounding factors. RESULTS The risk for having at least 1 positive reaction on a skin prick test was reduced (adjusted odds ratio, 0.43; 95% CI, 0.23-0.79, P = .007), and the concentration of cat-specific IgE was less (25% less; 95% CI, 43% to 2.3% less; P = .033) in sera from very-low-birth-weight subjects compared with that seen in sera from control subjects. Within the very-low-birth-weight group, those born at an earlier gestational age were less likely to have positive skin prick test reactions (adjusted odds ratio for 1 week, 0.82; 95% CI, 0.68-0.98, P = .029) and less likely to have high levels of allergen-specific IgE. Cumulative incidences of atopic disease were similar between adults of very low birth weight and control subjects. CONCLUSIONS Young adults born prematurely and at very low birth weight have a lower incidence of atopy than adults who were born full term. This finding supports the hypothesis that the risk for atopy is determined during early stages of development.