Limitations in the Activity of Mobility at Age 6 Years After Difficult Birth at Term: Prospective Cohort Study

Participants and Method

In order to understand the nature of our study group, we first summarize the Dutch health care system for obstetrical guidance, as it is different from that in most other industrialized countries.^18,19 Women with an uncomplicated pregnancy deliver either at home or in the outpatient clinic of a regional hospital under the guidance of a midwife. In case of imminent complications, women are admitted to clinical obstetrical care under surveillance of a gynecologist. If DBAT occurs and results in a severe form of asphyxia, the infant is referred to an academic center with MRI scanning and hypothermia treatment facilities. If DBAT results in less severe asphyxia, the infant is admitted to the pediatric department of the regional hospital.

In an index cohort, we recruited all consecutive infants with DBAT who were admitted to the neonatal unit of the Gelre Regional Hospital Apeldoorn, the Netherlands, between January 1, 1999, and July 1, 2005.²⁰ Infants were eligible for the index cohort if they were born at term (ie, birth after 36 completed weeks of gestation), if they were born in the hospital (referrals from midwife practices or outpatient hospital delivery), and if they fulfilled at least 2 of the following clinical criteria for DBAT: (1) abnormal cardiotocogram (ie, late decelerations, persistent bradycardia or persistent tachycardia), (2) Apgar score <7 at 5 minutes, (3) umbilical pH <7.20, and (4) umbilical base excess ≤10 mmol/L.^3,6,21 Infants with severe NE and with major congenital malformations were not eligible. Eighty infants presented with DBAT to the neonatal unit. The pediatrician (S.B.), within the first 24 hours after delivery and on the basis of neurological parameters, determined the degree of NE according to the grading of Sarnat and Sarnat⁴ (eTab. 1). Seventeen infants were not included because parents declined participation, resulting in an index cohort of 63 infants (Fig. 1). Infants who did participate (n=63) and those who did not participate (n=17) were similar in terms of inclusion criteria and severity of NE.

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Figure 1.

Flow diagram: intake of study group with difficult birth at term and reference group.

In a reference cohort, we recruited healthy term infants at the Gelre Hospital and nearby midwife practices during the same period (1999–2005). Again, infants with major congenital anomalies were not eligible. We matched infants in the reference cohort with the index cohort for sex, gestational age, birth weight, and cesarean section. We recruited the healthy term infants: (1) at home or in an outpatient clinic under the guidance of a midwife (n=63) or (2) from infants born in the hospital after cesarean section (n=21). In the latter infants, cesarean section was applied either because the mother previously had had a cesarean section or because delivery was not progressing. If the latter was the case, it still had resulted in the birth of a healthy neonate without signs of DBAT. In total, the reference cohort consisted of 84 term infants (Fig. 1).

The parents of the participants gave signed informed consent, and the procedures were approved by the Medical Ethical Committee of University Medical Center Utrecht (project number: 04-163). Clinical assessments (ie, Apgar scores, cardiotocogram, umbilical pH and base excess) were performed in all infants with DBAT as part of standard clinical care.

Children from both cohorts were invited for follow-up at 6 years of age. One child with moderate NE in the index cohort had died, and 3 children in the reference cohort belonged to families who declined participation, either because of assessment burden (n=2) or for logistical reasons (n=1; Fig. 1). The assessment at 6 years consisted of a motor and neurological assessment and a behavioral and academic evaluation by means of parental and teachers' questionnaires. In addition, parents completed a questionnaire on the child's medical history, including information on the use of paramedical care (speech therapy, physical therapy, or occupational therapy).

We assessed mobility with the Movement Assessment Battery for Children (MABC, version 1).²² The MABC has been developed to identify and evaluate children with mild-to-moderate limitations in activities, covered by the chapter “Mobility” of the ICF-CY.^22,23 The test consists of 4 age bands, each with 8 functional motor tasks representing: (1) manual dexterity (ICF-CY code d440: fine hand use); (2) ball skills (ICF-CY code d445: hand and arm use); and (3) static and dynamic balance skills (ICF-CY codes d410 and d455: changing basic body position and moving around, respectively).^13,22 Quantitative performance of each test item is scored from 0 (best) to 5 (worst). Item scores are added up, producing 3 subscores (ie, manual abilities, ball skills, and static and dynamic balance) and a total score. Performance on the total MABC is typical if >15th percentile (P15), borderline if 5th percentile (P5) ≤ score ≤ P15, or definitely impaired if <P5.²⁴ In the present study, we chose to dichotomize outcome on the total MABC into “typical” (>P15) and “limited” (≤P15). Performance in the 3 domains (manual abilities, ball skills, and balance) was considered typical if ≥P5 and limited if <P5.

The chosen cutoffs for the total score and the domain scores are recommended by the European Academy for Childhood Disability and the Dutch National Developmental Coordination Disorder Committee to use in the diagnosis of developmental coordination disorder (DCD).¹⁶ The MABC version 1 has good test-retest and interrater reliability, moderate concurrent validity lacking a suitable gold standard, and good construct validity.^23–26 The validity of the subscale scores is satisfactory.^24,27

In order to evaluate behavior, we asked the parents and teachers of all children to fill out Achenbach System of Empirically Based Assessment (ASEBA) questionnaires, which include the Child Behavior Checklist (CBCL; for parents) and the Teachers Report Form (TRF; for teachers).^28,29 For both questionnaires, we dichotomized the resulting scale and total scores on the basis of the T-scores into “typical” (score <95th percentile [P95]) and “behavioral problems” (score ≥P95, including both borderline and clinical scores). The reliability of the CBCL and TRF is good.³⁰ The concurrent validity of the CBCL and TRF based on correlations with outcome of related checklists and questionnaires also is good.^30–33 The TRF also comprises open questions about academic achievement, school grades, extra educational assistance, repetition of class, and attendance of a special school. Attendance of a special school in the Netherlands is based on the presence of physical, cognitive, and behavioral impairment, often a combination of these impairments. On the basis of this information, we defined the presence of learning problems as the presence of special assistance or special education or being in an inappropriate grade for age.^29,30

To assess neurological condition, we used the standardized, age-specific and criterion-referenced examination of the child with minor neurological dysfunction (MND).³⁴ This examination assesses the presence of MND in 8 domains: (1) dysfunctional posture and muscle tone regulation, (2) dysfunctional reflex activity, (3) mild dyskinesia (eg, choreiform or athetotiform movements), (4) mild problems in coordination, (5) mild problems in fine manipulative ability, (6) excessive associated movements, (7) mild cranial nerve dysfunction, and (8) mild sensory dysfunction. Importantly, a single sign has no clinical significance. Signs obtain significance if they cluster in a domain; for each domain, the criteria for dysfunction have been determined.³³ At school age, the assessment results in the following classification: (1) neurologically normal, implying the absence of dysfunctional domains or isolated dysfunction in the domain “reflexes”; (2) simple MND, denoting the presence of dysfunction in 1 or 2 domains; (3) complex MND, denoting the presence of dysfunction in at least 3 domains; and (4) neurologically abnormal, implying the presence of a clear neurological disorder, such as CP.³⁴ The diagnosis of CP implies the presence of a classical configuration of neurological signs as specified by the Surveillance of Cerebral Palsy in Europe network.³⁵ Simple MND is considered to reflect typical, but nonoptimal, brain function; complex MND is regarded as the clinically relevant form of MND, as it is clearly associated with motor, learning, and behavioral problems.^34,36

All children were independently assessed by 2 authors. The first author (P.I.), who was aware of the clinical condition of the children, performed the initial neurological examination. The last author (M.H-A.), who is a neurodevelopmental expert and was masked to all details of the child, assessed neurological condition on the basis of a video recording of the assessment of the first author. In case of disagreement between the authors, the findings of the expert were used. The MND assessment has good intrarater, interrater, and test-retest reliability (κ=.71–.83).^34,36–38 The construct validity, based on the relationship of MND with prenatal and perinatal adversities, is good.^34,39,40 The predictive validity also is good: severity of MND at 9 years of age is related to the risk of MND at 12 and 14 years of age and that of learning and behavioral problems at 9 and 14 years of age.^34,40–42

The primary outcome measure was limited mobility (MABC score ≤P15) at 6 years of age. The secondary outcome measure included presence of MND, whether the child had received physical therapy, and learning and behavioral problems assessed with the CBCL and TRF at 6 years of age.