Peter J Fleming

Environment of infants during sleep and risk of the sudden infant death syndrome: results of 1993-5 case-control study for confidential inquiry into stillbirths and deaths in infancy. Confidential Enquiry into Stillbirths and Deaths Regional Coordinators and Researchers.

Abstract Objective: To investigate the role of sleeping arrangements as risk factors for the sudden infant death syndrome after a national risk reduction campaign. Design: Two year population based case-control study. Parental interviews were conducted for each infant who died and for four controls matched for age and date of interview. Setting: Three regions in England with a total population of 17 million people. Subjects: 195 babies who died and 780 matched controls. Results: Prone and side sleeping positions both carried increased risks of death compared with supine when adjusted for maternal age, parity, gestation, birth weight, exposure to smoke, and other relevant factors in the sleeping environment (multivariate odds ratio = 9.00 (95% confidence interval 2.84 to 28.47) and 1.84 (1.02 to 3.31), respectively). The higher incidence of side rather than prone sleeping led to a higher population attributable risk (side 18.4%, prone 14.2%). More of the infants who died were found with bed covers over their heads (21.58; 6.21 to 74.99). The use of a dummy had an apparent protective effect (0.38; 0.21 to 0.70). Bed sharing for the whole night was a significant risk factor for infants whose mothers smoked (9.25; 2.31 to 34.02). No protective effect of breast feeding could be identified on multivariate analysis. Conclusions: This study confirms the importance of certain risk factors for the sudden infant death syndrome and identifies others—for example, covers over the head, side sleeping position—which may be amenable to change by educating and informing parents and health care professionals. Key messages This large case-control study is the first after the national campaign to reduce the risk of the syndrome The risk of sudden infant death is increased by prone or side sleeping position; loose bedding (particularly duvets), which can slip over the babys head; and bed sharing by mothers who smoke The risk may be reduced by supine sleeping position; placing the baby with feet at the foot of the cot (“feet to foot”); ensuring that bedding is securely tucked in; and avoiding the use of duvets

Smoking and the sudden infant death syndrome: results from 1993-5 case-control study for confidential inquiry into stillbirths and deaths in infancy

Abstract Objective: To investigate the effects of exposure to tobacco smoke and of parental consumption of alcohol and illegal drugs as risk factors for the sudden infant death syndrome after a national risk reduction campaign which included advice on prenatal and postnatal avoidance of tobacco smoke. Design: Two year population based case-control study. Parental interviews were conducted for each infant who died and four controls matched for age and date of interview. Setting: Three regions in England with a total population of 17 million people. Subjects: 195 babies who died and 780 matched controls. Results: More index than control mothers (62.6% v 25.1%) smoked during pregnancy (multivariate odds ratio = 2.10; 95% confidence interval 1.24 to 3.54). Paternal smoking had an additional independent effect when other factors were controlled for (2.50; 1.48 to 4.22). The risk of death rose with increasing postnatal exposure to tobacco smoke, which had an additive effect among those also exposed to maternal smoking during pregnancy (2.93; 1.56 to 5.48). The population attributable risk was over 61%, which implies that the numbers of deaths from the syndrome could be reduced by almost two third if parents did not smoke. Alcohol use was higher among index than control mothers but was strongly correlated with smoking and on multivariate analysis was not found to have any additional independent effect. Illegal drug use was more common among the index parents, and paternal use of illegal drugs remained significant in the multivariate model (4.68; 1.56 to 14.05). Conclusions: This study confirms the increased risk of the sudden infant death syndrome associated with maternal smoking during pregnancy and shows evidence that household exposure to tobacco smoke has an independent additive effect. Parental drug misuse has an additional small but significant effect. Key messages Exposure of babies to tobacco smoke from other members of the household before or after birth increases the risk of death: the greater the exposure the higher the risk Over 60% of such deaths may be attributable to the effects of exposure to tobacco smoke before and after birth

Epidemiology of SIDS and Explained Sudden Infant Deaths

Objectives. To establish whether epidemiologic characteristics for sudden infant death syndrome (SIDS) have changed since the decrease in death rate after the “Back to Sleep” campaign in 1991, and to compare these characteristics with sudden and unexpected deaths in infancy (SUDI) from explained causes. Design. Three-year, population-based, case-control study. Parental interviews were conducted soon after the death and for 4 controls matched for age and date of interview. All sudden unexpected deaths were included in the study and the cause of death was established by a multidisciplinary panel of the relevant health care professionals taking into account past medical and social history of the mother and infant, the circumstances of death, and a full pediatric postmortem examination. Contributory factors and the final classification of death were made using the Avon clinicopathologic system. Setting. Five regions in England, with a total population of >17 million people, took part in the study. The number of live births within these regions during the particular time each region was involved in the study was 473u2009000. Study Participants. Three hundred twenty-five SIDS infants (91.3% of those available), 72 explained SUDI infants (86.7% of those available), and 1588 matched control infants (100% of total for cases included). Results. Many of the epidemiologic features that characterize SIDS infants and families have remained the same, despite the recent decrease in SIDS incidence in the United Kingdom. These include the same characteristic age distribution, few deaths in the first few weeks of life or after 6 months, with a peak between 4 and 16 weeks, a higher incidence in males, lower birth weight, shorter gestation, and more neonatal problems at delivery. As in previous studies there was a strong correlation with young maternal age and higher parity and the risk increased for infants of single mothers and for multiple births. A small but significant proportion of index mothers had also experienced a previous stillbirth or infant death. The majority of the SIDS deaths (83%) occurred during the night sleep and there was no particular day of the week on which a significantly higher proportion of deaths occurred. Major epidemiologic features to change since the decrease in SIDS rate include a reduction in the previous high winter peaks of death and a shift of SIDS families to the more deprived social grouping. Just more than one quarter of the SIDS deaths (27%) occurred in the 3 winter months (December through February) in the 3 years of this study. In half of the SIDS families (49%), the lone parent or both parents were unemployed compared with less than a fifth of control families (18%). This difference was not explained by an excess of single mothers in the index group. Many of the significant factors relating to the SIDS infants and families that distinguish them from the normal population did not distinguish between SIDS and explained SUDI. In the univariate analysis many of the epidemiologic characteristics significant among the SIDS group were also identified and in the same direction among the infants dying as SUDI attributable to known causes. The explained deaths were similarly characterized by the same infant, maternal, and social factors, 48% of these families received no waged income. Using logistic regression to make a direct comparison between the two index groups there were only three significant differences between the two groups of deaths: 1) a different age distribution, the age distribution of the explained deaths peaked in the first 2 months and was more uniform thereafter; 2) more congenital anomalies were noted at birth (odds ratio [OR] = 3.14; 95% confidence intervals [CI]: 1.52–6.51) among the explained deaths (20%) compared with the SIDS (8%), which was not surprising given that 10% of these deaths were explained by congenital anomalies; and 3) a higher incidence of maternal smoking during pregnancy among the SIDS mothers, the proportion of smokers within the explained SUDI group was much higher (49%) than the controls (27%), but among SIDS mothers the proportion of smokers was higher still (66%) and this difference was significant (66% vs 49%; OR = 2.03; 95% CI: 1.16–3.54). The largest subgroup of explained SUDI deaths were those attributable to infection (46%). There was a winter peak of deaths from infection, the highest number occurring in December (21%) but this was not significant. A multivariate model of these deaths showed parental unemployment to be the most significant factor (OR = 27.74; 95% CI: 3.19–241.34). Short gestational age (OR = 11.67; 95% CI: 1.84–74.14), neonatal problems (OR = 14.27; 95% CI: 1.89–107.81), and higher prevalence of males (OR = 9.26; 95% CI: 1.63–52.52) were also significant. Half of the deaths from infection occurred in crowded households (>1 adult or child per room excluding hallways, toilets, bathrooms, and kitchens if not used as a dining room) which was also a significant factor (OR = 10.37; 95% CI: 1.08–99.59). Conclusions. The study identifies changes in the epidemiologic characteristics of SIDS that have followed the “Back to Sleep” campaign, and confirms that many underlying factors are similar between infants who die as SIDS and those dying suddenly of explained causes. Many studies investigating SIDS have reported numerous epidemiologic characteristics and risk factors strongly associated with SIDS when compared with live control infants. It has been generally assumed that these factors are specific to SIDS to the extent that the syndrome has been described as an “epidemiologic entity.” Many of the factors associated with SIDS that were significantly different from the control population were not significantly different when compared with the explained deaths. This suggests that SUDI share some of the same underlying factors irrespective of the clinical or pathologic findings, and challenges a rigid concept of SIDS as an epidemiologic entity. The particular finding that the incidence of maternal smoking during pregnancy, although high among mothers of explained SUDI infants, was significantly higher among SIDS mothers, lends weight to the mounting evidence that the association between smoking and SIDS may be part of a causal mechanism.

Sleep influences on homeostatic functions: implications for sudden infant death syndrome.

The mechanisms underlying the sudden infant death syndrome (SIDS) appear to have origins in the fetal environment resulting in neural damage which later compromises responses to breathing or blood pressure challenges during sleep. The deficits appear to involve alterations in neurotransmitter receptors within regions involved in chemoreception and cardiovascular control. SIDS risk is enhanced by pre- and postnatal nicotine exposure, and possibly by hypoxic experiences. The prone sleeping position plays a significant role in risk, as do head positions that minimize facial escape from enclosed spaces; elevated body temperature may also be a factor. Compensatory mechanisms, including diminished gasping ability, relative failure to arouse to a safer state, or a failure to recruit respiratory efforts to overcome a blood pressure loss have been the object of recent research efforts. The findings suggest that the fatal event involves a neurally-compromised infant, circumstances that challenge vital physiology, most likely during sleep, at a particular developmental period.

Socio-demographic associations with digit and pacifier sucking at 15 months of age and possible associations with infant infection

AIMSnTo assess the prevalence of pacifier and digit sucking at 15 months of age and to investigate whether this habit adversely affects the health of 18 month old infants.nnnSTUDY DESIGNnData collected via self-completion questionnaires from mothers forming part of the prospective, population based Avon Longitudinal Study of Pregnancy and Childhood.nnnSUBJECTS AND METHODSnThe mothers of 10006 infants gave information on their childs use of a pacifier and of digit sucking at 15 months of age and the presence of specific health symptoms at 18 months of age. Adjusted logistic regression was performed to identify any statistically significant associations between pacifier use, digit sucking or a combination of the two with possible infection.nnnRESULTSn36.3% of infants sucked a pacifier, 21. 3% their thumb or finger and 2.7% sucked both at 15 months. Statistically significant differences were observed among various socio-demographic variables. Mothers were more likely to give their child a pacifier if they were younger, had lower levels of education, experienced greater financial difficulties or lived in council housing (compared to owned/mortgaged). The opposite was apparent for digit suckers. After allowing for these possible confounding factors, pacifier users had a higher incidence of earache and colic compared to children with no sucking habit, however digit suckers had a lower incidence of these symptoms. Children who sucked both were significantly more likely to have reported wheezing, earache, and poor health in the past month.nnnCONCLUSIONSnSignificantly different sociodemographic characteristics were observed with pacifier suckers compared to those who sucked their thumb or finger. It is almost impossible to attribute the direction of causality between infection and a sucking habit. Further and more detailed studies are needed before any recommendations can be made based on the statistically significant associations found as they are unlikely to be of major clinical significance.

Night-time non-nutritive sucking in infants aged 1 to 5 months: relationship with infant state, breastfeeding, and bed-sharing versus room-sharing

AIMnEpidemiological studies suggest that pacifier use may be protective against SIDS but little is known of the relationship between pacifier use and other forms of non-nutritive sucking (NNS) in infancy, or of patterns of NNS during the night, when most SIDS deaths occur. We report the first longitudinal study of NNS by direct overnight observations in healthy infants in a sleep laboratory.nnnMETHODSnHealthy, breast fed term infants (n = 10) were enrolled at birth, and sequential overnight polygraphic and infrared video recordings of infants with their mothers performed at monthly intervals from 1 to 5 months. Each month, mother baby pairs were randomized to 1 night bed-sharing (BN) then 1 room-sharing (RN), or vice versa. Episodes of pacifier, own digit and mothers digit sucking (> 1 min) were identified and compared with state-matched control periods without sucking or feeding before and after each such episode.nnnRESULTSn329 episodes of NNS were identified in 749 h of video recording. The prevalence of pacifier sucking decreased with age, whilst digit sucking increased. Routine pacifier users rarely sucked their digits. There were temporal differences throughout the night in the distribution of different types of sucking and in infant state during and around sucking episodes. Sleeping in the non-routine location was associated with a larger percentage of nights with sucking episodes and increased sleep latency. Bed sharing (routinely or on a given night) was associated with less sucking behavior and more breastfeeding. Non-nutritive sucking was not, however, associated with decreased total time breastfeeding per night or number of feeds per night.nnnCONCLUSIONnPatterns of NNS during the night change with age and are affected by maternal proximity. Digit sucking has state modulating effects, and may be suppressed by pacifier use. Thus any benefits of pacifier use must be set against the potential loss of a self-directed ability to modulate state during the night, and possible shortening of breastfeeding duration.

Development of visual evoked potentials following intrauterine growth retardation

Visual evoked potentials to flash (FVEP) were recorded in 23 symmetrically growth retarded newborns of between 32 and 39 weeks gestational age and 41 normally grown controls. At 9 months post term FVEP recordings were repeated in 14 of the growth retarded and 26 of the control infants. The development of two long latency negative components of the wave form of the neonatal FVEP was delayed in the growth retarded infants. The amplitude of a long latency negative peak in the 9 month post term FVEP was reduced in the growth retarded infants. We suggest that intrauterine growth retardation may affect the development of secondary activity in the visual cortex.

Abnormal development of visual function following intrauterine growth retardation

Vernier acuity was measured at 40 weeks post term in 18 infants born with symmetric intrauterine growth retardation (IUGR) and 32 normal (N) infants. Grating acuity was also measured in 12 IUGR and 26 N infants. The mean vernier detection threshold (V.min) was 0.4 octaves higher in the IUGR than in the N infants (P less than 0.04). The mean grating detection threshold (S.min) was 0.2 octaves lower in the IUGR infants (NS). The mean ratio of S.min to V.min was significantly lower in the IUGR infants (1.5 IUGR, 2.7 N, P less than 0.05). V.min was significantly negatively correlated with the head circumference of the IUGR infants at 40 weeks post term. Vernier acuity depends on visual processing at a cortical level. The normal grating acuity in the IUGR infants implies that cortical, rather than optical or retinal factors, underlie the reduced vernier acuity (high V.min). We suggest that the cortical representation of visual space is affected by IUGR.