Repeat sudden unexpected and unexplained infant deaths: natural or unnatural?

BACKGROUND: There have been suggestions that when two or three unexpected unexplained infant deaths occur within a family they are more likely to be unnatural than natural. We aimed to estimate the probability that a second infant death is natural versus unnatural. METHODS: The Care of Next Infant programme (CONI) supports parents who have previously had an unexpected and apparently unexplained infant death and is currently available in over 90% of health districts in England, Wales, and Northern Ireland. We studied all deaths in 6373 infants who had completed the CONI programme by December, 1999. After a CONI death, we made detailed enquiries into the previous death and the CONI death, including a family interview, a review of autopsies, and case discussion. FINDINGS: 57 (8.9 per 1000) CONI infants died. Nine deaths were inevitable, and 48 were unexpected. 44 families lost one child, and two families lost two children. Of the 46 first CONI deaths, 40 were natural; the other six were probable homicides, five committed by one or both parents (two criminally convicted). The ratio of 40 natural to six unnatural deaths is 6.7 (95% CI 2.8-19.4). Enquiries identified 18 families with two SIDS(sudden infant death syndrome) deaths and two families with probable covert double homicides (ratio 9.0 [2.2 to 80.0]). There were no convictions in 13 incomplete cases. Families with three deaths are reported. INTERPRETATION: Repeat unexpected infant deaths are most probably natural.

Sudden unexplained infant death in 20 regions in Europe: case control study.

BACKGROUND: After striking changes in rates of sudden unexplained infant death (SIDS) around 1990, four large case-control studies were set up to re-examine the epidemiology of this syndrome. The European Concerted Action on SIDS (ECAS) investigation was planned to bring together data from these and new studies to give an overview of risk factors for the syndrome in Europe. METHODS: We undertook case-control studies in 20 regions. Data for more than 60 variables were extracted from anonymised records of 745 SIDS cases and 2411 live controls. Logistic regression was used to calculate odds ratios (ORs) for every factor in isolation, and to construct multivariate models. FINDINGS: Principal risk factors were largely independent. Multivariately significant ORs showed little evidence of intercentre heterogeneity apart from four outliers, which were eliminated. Highly significant risks were associated with prone sleeping (OR 13.1 [95% CI 8.51-20.2]) and with turning from the side to the prone position (45.4 [23.4-87.9]). About 48% of cases were attributable to sleeping in the side or prone position. If the mother smoked, significant risks were associated with bed-sharing, especially during the first weeks of life (at 2 weeks 27.0 [13.3-54.9]). This OR was partly attributable to mother's consumption of alcohol. Mother's alcohol consumption was significant only when baby bed-shared all night (OR increased by 1.66 [1.16-2.38] per drink). For mothers who did not smoke during pregnancy, OR for bed-sharing was very small (at 2 weeks 2.4 [1.2-4.6]) and only significant during the first 8 weeks of life. About 16% of cases were attributable to bed-sharing and roughly 36% to the baby sleeping in a separate room. INTERPRETATION: Avoidable risk factors such as those associated with inappropriate infants' sleeping position, type of bedding used, and sleeping arrangements strongly suggest a basis for further substantial reductions in SIDS incidence rates.

Prevention of unexpected infant death. A review of risk-related intervention in six centers.

Over seventy percent of unexpected infant deaths are registered as SIDS. Over 85,000 infants have been screened at birth and one month of age for risk of unexpected death using the Sheffield Score system. Scores range from below 400 to over 800 points. Infants with scores over 800 are at more than 16 times greater risk than infants with scores below 400. Family doctors and health visitors were alerted to high-risk infants, who were examined at home and weighed naked at home five times in the first six months. Mortality in the high-risk group was reduced by more than 50% (p less than 0.02 in one area and p less than 0.05 in another). It is concluded that with few extra resources unexpected infant mortality can be reduced by 25% by this approach.

Effect of ventromedial hypothalamic lesions on the secretion of somatostatin, insulin, and glucagon by the perfused rat pancreas.

Somatostatin, insulin, and glucagon secretion by the perfused pancreas were studied in adult female rats 10 days after ventromedial hypothalamic (VMH) lesions and in sham operated controls to assess the role of their hypothalamic control. Insulin secretion was significantly greater in VMH-lesioned rats both under basal conditions and after stimulation by theophylline and arginine plus theophylline. Basal glucagon secretion was greater in VMH-lesioned rats as was the glucagon response to theophylline alone and in combination with arginine. Basal somatostatin secretion with similar in VMH and control rats but somatostatin secretion induced by theophylline and by arginine plus theophylline was significantly increased in VMH-lesioned rats. Both the pancreatic content and concentration of somatostatin were increased in VMH-lesioned rats. These results indicate the presence of hyperresponsiveness of A, B, and D cells following VMH destruction and provide new evidence for a role of the hypothalamus in the regulation of pancreatic somatostatin secretion.

Parents seeking help after cot death. How atypical is their experience?

A survey of 241 cases of cot death reported to the Foundation for the Study of Infant Deaths is compared with more formal epidemiological studies. As expected the cases tend to be drawn from the higher social classes, and this selection affects some of the data--for instance, mothers' age and feeding practice. Nevertheless, data relating to the infants and their histories are remarkably similar to data from other studies. The survey provides a continuous epidemiological monitor as well as being of therapeutic value to the parents and should be continued.

Reversible obesity and plasma fat metabolites.

Rats were made to overeat and gain weight (about 50 g) by long-acting protamine zinc insulin (PZI) treatment. When the PZI treatment was stopped, the rats ate much less than normal for at least seven days. During recovery from PZI-induced obesity, negative correlations were observed between food intake and plasma levels of the fat metabolites, free fatty acids, glycerol, and ketone bodies. A similar but smaller effect was observed during recovery from dietary obesity (about 15 g). The plasma fat metabolites may be the blood-borne signals which suppress hunger under these conditions.

Plasma fat metabolites and hunger.

In order to test the hypothesis that the fat metabolites are the blood-borne signals which suppress hunger during recovery from reversible obesity, experiments were designed to manipulate plasma fat metabolite levels directly. In order to elevate plasma glycerol levels, glycerol was infused intravenously into relatively unrestrained rats for 36 hours; this treatment greatly increased plasma glycerol levels but reduced voluntary food intake only slightly. Similar results were obtained when glycerol was mixed with powdered rat food. These results suggest that glycerol is not the "lipostatic hormone" although it may contribute to regulation. Similar experiments with a synthetic precursor of the ketone bodies (1,3 butanediol), suggest that the ketone bodies contribute to the decrease in food intake after reversible obesity, but cannot be a complete explanation. Dietary fat consumption raised plasma free fatty acid (FFA) levels to the range seen during recovery from reversible obesity, suggesting that plasma FFAs may be a blood-borne signal of fat utilization in both cases. Intralipid, a synthetic triglyceride emulsion designed for intravenous administration, also increased plasma FFA levels but suppressed food intake by less than predicted. However, Intralipid may tend to cause spuriously high plasma FFA readings for reasons which are discussed. These results suggest that plasma fat metabolites, especially FFAs, may be blood-borne signals which contribute to the voluntary dieting after reversible obesity.

Early streptozotocin diabetes and hunger.

The initial effect of streptozotocin diabetes is not hyperphagia, but reduced food intake. Diabetic hyperphagia reaches maximum only after many days. Utilization of body fat may account for the delayed appearance of diabetic hyperphagia; this effect may be mediated by plasma fat metabolites. Plasma levels of free fatty acids (FFAs), ketone bodies, and glycerol are greatly elevated following STZ treatment, but return nearly to normal as diabetic hyperphagia appears.

VMH obesity reduced but not reversed by scopolamine methyl nitrate.

Chronic administration of scopolamine methyl nitrate, at doses much greater than required to block vagally mediated insulin secretion, reduced static phase VMH obesity by only 31%. At least 59% of the obesity persisted even when the initially effective dose (0.15 mg/Kg, 4 times/day) was increased eight-fold. The larger dose also did not prevent VMH hyperphagia and weight gain when scopolamine treatment was begun before the lesion. By ten days after the lesion, reduced gastrointestinal motility apparently prevented further weight gain. These results suggest that much of the obesity caused by VMH lesions is independent of vagally mediated insulin secretion or other excess vagal efferent activity. The doses used in this experiment were large in order to provide strong evidence for this conclusion.

Is postnatal depression a risk factor for sudden infant death?

BACKGROUND: In New Zealand, an association has been shown between postnatal depression and sudden infant death syndrome (SIDS). AIM: To replicate the New Zealand study. DESIGN OF STUDY: Case-control study. SETTING: The city of Sheffield, UK. METHOD: The database of the Sheffield Child Development Study was used Demographic and obstetric data were collected and at one month postpartum the Edinburgh Postnatal Depression Scale (EPDS) was administered. Detailed information on the cause of all infant deaths was available. RESULTS: There were 32,984 live births during the study period (from the year 1988 to 1993) and 42 babies died with the cause registered as SIDS. Multivariate analysis showed that smoking was the most important risk factorfor SIDS (odds ratio [OR] = 7.24, 95% confidence interval [95% CI] = 2.76 to 19.01), followed by a high EPDS (OR = 3.20, 95% CI = 1.46 to 6.99) and residence in an area of poverty (OR = 2.33, 95% CI = 1.06 to 5.11). CONCLUSIONS: The Sheffield data confirm the New Zealand findings. A high EPDS score and, by implication, postnatal depression, may be risk factors for SIDS, however, there are many possible explanations for the association.