A review and psychometric evaluation of pregnancy-specific stress measures

Considerable evidence has accumulated on the association between pregnancy-specific stress and adverse birth outcomes with an increasing number of measures of pregnancy-specific stress being developed internationally. However, the introduction of these measures has not always been theoretically or psychometrically grounded, resulting in questions about the quality and direction of such research. This review summarizes evidence on the reliability and validity of pregnancy-specific stress measures identified between 1980 and October 2010. Fifteen pregnancy-specific stress measures were identified. Cronbach’s alpha coefficient ranged from 0.51–0.96 and predictive validity data on preterm birth were reported for five measures. Convergent validity data suggest that pregnancy-specific stress is related to, but distinct from, global stress. Findings from this review consolidate current knowledge on pregnancy-specific stress as a consistent predictor of premature birth. This review also advances awareness of the range of measures of pregnancy-specific stress and documents their strengths and limitations based on published reliability and validity data. Careful consideration needs to be given as to which measures to use in future research to maximize the development of stress theory in pregnancy and appropriate interventions for women who experience stress in pregnancy. An international, strategic collaboration is recommended to advance knowledge in this area of study.

Cord blood erythropoietin, pH, PaO2 and haematocrit following caesarean section before labour

We have investigated the relationship between erythropoietin (Epo) and pH, PaO2 and haematocrit in 100 cord blood samples obtained at Caesarean section prior to labour. Of 82 term (> 37 weeks) infants, 64 were appropriately grown (10th-90th centiles), and their mean cord serum Epo and cord blood Epo was 23 +/- 8 mU/ml (mean +/- SD). Strong inverse correlations were found between cord serum Epo and cord blood pH (r = -0.74; p <0.0001), and between cord serum Epo and cord blood PaO2 (r = -0.55; p <0.0001), but not between cord serum Epo and cord haematocrit (r = 0.02; p <0.9). For the 18 preterm babies (gestation 32.4 +/- 4.1 weeks, birth weight 1,820 +/- 476 g), the Epo level was 36 +/- 8 mU/ml, which was not significantly greater than for the term babies. Strong inverse correlations were again found between Epo and pH (r = -0.87; p <0.0001) and Epo and PaO2 (r = -0.69; p <0.002). Babies from complicated pregnancies (intra-uterine growth retardation, pre-eclampsia, antepartum haemorrhage, diabetes mellitus and fetal distress) tended to have higher Epo levels. Thirteen babies had Epo levels > 40 mU/ml, and 11 (85%) of these required neonatal intensive care. Cord serum Epo correlates better with oxygen tension and pH at birth than with fetal growth and haematocrit, which are measures of chronic stress to the fetus.

The neurodevelopmental progress of infants less than 33 weeks into adolescence

Background: Several studies have shown an increased incidence of neurodevelopmental impairment in very preterm survivors at school age compared with controls.

Aim: To compare findings in the same cohort at 8 years and 15 years.

Methods: A total of 151 of the 224 eligible infants born before 33 weeks of gestation from 1979 to 1982, and who were living in the UK, were assessed at 8 and 15 years. Items common to both assessments were compared to evaluate changes in neurodevelopmental function. The assessment included a structured neurological examination, psychometric tests using the WISC-R (in subjects born in 1981-82), a test of visuomotor integration (Beery), and a school questionnaire.

Results: There was a significant increase in the proportion of subjects classified as impaired with disability from 11% at 8 to 22% at 14-15 years of age. The proportion of subjects classified as impaired without disability increased from 16% at 8 to 26% at 14-15 years of age. Full scale IQ decreased from 104 to 95 from childhood to adolescence, and more adolescents (24%) were requiring extra educational provision than they had at the age of 8 years (15%).

Conclusion: Results indicate that between the ages of 8 and 15 years in this cohort of very preterm survivors there is an apparent deterioration in neurodevelopmental outcome category, cognitive function, and extra educational support. It is not clear whether this represents a genuine deterioration in neurocognitive function or whether it represents the expression of pre-existing cerebral pathology in an increasingly complex environment.

Procedural pain and brain development in premature newborns

Objective: Preterm infants are exposed to multiple painful procedures in the neonatal intensive care unit (NICU) during a period of rapid brain development. Our aim was to examine relationships between procedural pain in the NICU and early brain development in very preterm infants.

Methods: Infants born very preterm (N ¼ 86; 24–32 weeks gestational age) were followed prospectively from birth, and studied with magnetic resonance imaging, 3-dimensional magnetic resonance spectroscopic imaging, and diffusion tensor imaging: scan 1 early in life (median, 32.1 weeks) and scan 2 at term-equivalent age (median, 40 weeks). We calculated N-acetylaspartate to choline ratios (NAA/choline), lactate to choline ratios, average diffusivity, and white matter fractional anisotropy (FA) from up to 7 white and 4 subcortical gray matter regions of interest. Procedural pain was quantified as the number of skin-breaking events from birth to term or scan 2. Data were
analyzed using generalized estimating equation modeling adjusting for clinical confounders such as illness severity, morphine exposure, brain injury, and surgery.

Results: After comprehensively adjusting for multiple clinical factors, greater neonatal procedural pain was associated with reduced white matter FA (b ¼ 0.0002, p ¼ 0.028) and reduced subcortical gray matter NAA/choline (b ¼ 0.0006, p ¼ 0.004). Reduced FA was predicted by early pain (before scan 1), whereas lower NAA/choline was predicted by pain exposure throughout the neonatal course, suggesting a primary and early effect on subcortical structures with secondary white matter changes.

Interpretation: Early procedural pain in very preterm infants may contribute to impaired brain development.

Survival without disability to age 5 years after neonatal caffeine therapy for apnea of prematurity

Very preterm infants are prone to apnea and have an increased risk of death or disability. Caffeine therapy for apnea of prematurity reduces the rates of cerebral palsy and cognitive delay at 18 months of age.

Is it painful or not?:Discriminant validity of the Behavioral Indicators of Infant Pain (BIIP) scale

To evaluate the ability of the Behavioral Indicators of Infant Pain (BIIP) scale to discriminate between skin-breaking and nonskin breaking procedures, and to identify sensitized pain responses in preterm infants in the neonatal intensive care unit (NICU).

Initial validation of the Behavioral Indicators of Infant Pain (BIIP)

Accurate pain assessment in preterm infants in the neonatal intensive care unit (NICU) is complex. Infants who are born at early gestational ages (GA), and who have had greater early pain exposure, have dampened facial responses which may lead to under-treatment. Since behavioral and physiological responses to pain in infants are often dissociated, using multidimensional scales which combine these indicators into a single score may limit our ability to determine the effects of interventions on each system. Our aim was to design a unidimensional scale which would combine the relatively most specific, individual, behavioral indicators for assessing acute pain in this population. The Behavioral Indicators of Infant Pain (BIIP) combines sleep/wake states, 5 facial actions and 2 hand actions. Ninety-two infants born between 23 and 32 weeks GA were assessed during 3, 1 min Phases of blood collection. Outcome measures included changes in BIIP and in Neonatal Infant Pain Scale (NIPS) scores coded in real time from continuous bedside video recordings; changes in heart rate (HR) were obtained using custom physiological processing software. Scores on the BIIP changed significantly across Phases of blood collection (p

Altered basal cortisol levels at 3, 6, 8 and 18 months in infants born at extremely low gestational age

Little is known about the developmental trajectory of cortisol levels in preterm infants after hospital discharge.

Long-term consequences of pain in human neonates

The low tactile threshold in preterm infants when they are in the neonatal intensive care unit (NICU), while their physiological systems are unstable and immature, potentially renders them more vulnerable to the effects of repeated invasive procedures. There is a small but growing literature on pain and tactile responsivity following procedural pain in the NICU, or early surgery. Long-term effects of repeated pain in the neonatal period on neurodevelopment await further research. However, there are multiple sources of stress in the NICU, which contribute to inducing high overall 'allostatic load', therefore determining specific effects of neonatal pain in human infants is challenging.

Are twitches, startles, and body movements pain indicators in extremely low birth weight infants?

The goal of this study was to examine whether body activity such as postural, trunk, and limb movements may be potential pain cues in preterm infants.

Judging pain in infants:behavioural, contextual, and developmental determinants

Caretakers intuitively use various sources of evidence when judging infant pain, but the relative importance of salient cues has received little attention. This investigation examined the predictive significance for judgements of painful discomfort in preterm and full-term neonates of behavioural (facial activity and body movement), contextual (invasiveness of the procedure), and developmental (gestational age) information. Judges viewed videotapes showing infants varying in the foregoing characteristics undergoing heel incisions for routine blood sampling purposes. Findings indicated all but the contextual information contributed uniquely to judgements of pain, with facial activity accounting for the most unique variance (35%), followed by bodily activity and gestational age, each accounting for 3% and 1% of the judgmental variance, respectively. Generally, 71% of the variance in ratings of pain could be predicted using facial activity alone, compared to 30% of the variance using bodily activity alone, 19% by relying on context alone, and 8% by referring to gestational age alone. Noteworthy was the tendency to judge early preterm infants to be experiencing less pain even though they were subjected to the same invasive procedure as the older infants. This finding also runs counter to evidence from developmental neurobiology which indicates that preterm newborns may be hypersensitive to invasive procedures.

A comparison of two measures of facial activity during pain in the newborn child

Facial activity is strikingly visible in infants reacting to noxious events. Two measures that reduce this activity to composite events, the Neonatal Facial Coding System (NFCS) and the Facial Action Coding System (FACS), were used to examine facial expressions of 56 neonates responding to routine heel lancing for blood sampling purposes. The NFCS focuses upon a limited subset of all possible facial actions that had been identified previously as responsive to painful events, whereas the FACS is a comprehensive system that is inclusive of all facial actions. Descriptions of the facial expressions obtained from the two measurement systems were very similar, supporting the convergent validity of the shorter, more readily applied system. As well, the cluster of facial activity associated with pain in this sample, using either measure, was similar to the cluster of facial activity associated with pain in adults and other newborns, both full-term and preterm, providing construct validity for the position that the face encodes painful distress in infants and adults.

Early pain experience, child and family factors, as precursors of somatization:a prospective study of extremely premature and fullterm children

In a prospective study of 36 children who were extremely low birthweight (ELBW: <1000 g) preterm infants and 36 matched full-term controls, differences were found in somatization at age 4 1/2 years. Only children who had been extremely premature, and thereby experienced prolonged hospitalization and repeated medical intervention in infancy, had clinically high somatization scores on the Personality Inventory for Children. The combination of family relations at age 4 1/2 years, neonatal intensive care experience, poor maternal sensitivity to child cues in mother-child interaction observed at age 3 years, and child avoidance of touch or holding at age 3, predicted somatization scores, prior to school entry. Due to the known higher incidence of actual medical problems among children with a history of extreme prematurity, the high somatization ELBW children were compared with the normal somatization ELBW children. There were no differences in prevalence of actual medical problems between the 2 ELBW groups, and the importance of maternal factors in relation to somatization was confirmed. Child temperament at age 3, but not personality at 4 1/2, was related to somatization. The etiology of recurrent physical complaints of no known medical cause appears to be a multi-dimensional problem. Non-optimal parenting may contribute to the development of inappropriate strategies for coping with common pains of childhood, or of chronic pain patterns, in some children who have experienced prolonged or repeated pain as neonates.

Language development at 3 years in pre-term children of birth weight below 1000 g

Language development at 3 years of pre-term children born below 1000 g birth weight was compared with full-term controls matched for social background. The pre-term group used less complex expressive language and showed lower receptive understanding, auditory memory and verbal reasoning. Language outcome was related to intraventricular haemorrhage but not to global indication of postnatal illness such as number of days on the ventilator. Average verbal intelligence in environmentally low risk, extremely low birth weight children is an insufficient indicator of complex language functioning.

Neurological, psychological and educational sequelae of low birth weight

In a prospective study of 501 infants of low birth weight (LBW) who mostly weighed 2,041 g (4 1/2 lb) or less, and of 203 control infants of full birth weight (FBW > 2,500 g), 335 LBW and 139 FBW children were followed beyond the age of 6 years and 6 months. The incidence of neurological defects was negatively correlated with birth weight, and the mean "global" IQ of different birth weight groups retained a direct relationship. While the relationship of birth weight to IQ gradually became less marked, the effect of social class was increasingly evident from the age of 2 years and 6 months. The preterm children whose birth weight was appropriate for gestational age (AGA) attained a slightly higher mean IQ and significantly better grade placement in the third school year than the children who were unduly light for their gestational age. Details of the neurological and ophthalmological defects are given, and the predictive significance of neonatal variables is analyzed.