Combined effects of sleeping position and prenatal risk factors in sudden infant death syndrome: the Nordic Epidemiological SIDS Study.

• Prone sleeping is a strong risk factor for sudden infant death syndrome (SIDS). We investigated whether the combined effect of prone sleeping position and prenatal risk factors further increased the SIDS risk.In the Nordic Epidemiological SIDS Study, parents of SIDS victims in Denmark, Norway, and Sweden completed a questionnaire on potential risk factors for SIDS. Forensic pathologists verified the SIDS diagnosis. Four controls of the same gender, age, and place of birth were selected. This matched case-control study, which included 244 SIDS cases and 869 controls from 1992 to 1995, was analyzed by conditional logistic regression.Odds ratios (ORs) for prone and side sleeping compared with supine sleeping for the last sleep were 13.9 (95% confidence interval 8.2-24) and 3.5 (2.1-5.7). Infants 13 to 24 weeks old had particularly high risk in prone and side sleeping, at 28.5 (7.9-107) and 5.9 (1.6-22). OR for prone sleeping was higher in girls, at 30.4 (11-88), than in boys, 10.3 (5.5-19). We found strong combined effects of sleeping position and prenatal risk factors (more than multiplicative). The OR for prone and side sleeping was increased for infants with birth weight <2500 g, at 83 (25-276) and 36.6 (13-107); for preterm infants, at 48.8 (19-128) and 40.5 (14-115); and for intrauterine growth retarded, at 38.8 (14-108) and 9.6 (4.3-22), compared with supine position in infants without these prenatal factors. The combined effect of nonsupine positions and intrauterine growth retarded was highest among 13- to 24-week-old infants. Effects of combined presence of nonsupine sleeping positions and each of the factors of smoking in pregnancy, young maternal age, higher parity, low level of maternal education, and single motherhood were more than additive. Attributable fractions in the population for prone and side sleeping were 18.5% and 26.0%.Both prone and side sleeping increased the risk of SIDS. The risk was increased further in low birth weight infants, preterm infants, and infants at the age of 13 to 24 weeks, suggesting that SIDS may be triggered by nonsupine sleeping in infants with prenatal risk factors during a vulnerable period of postnatal development.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Pediatrik (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Pediatrics (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Folkhälsovetenskap, global hälsa, socialmedicin och epidemiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Public Health, Global Health, Social Medicine and Epidemiology (hsv//eng)

Keyword

Age Factors

Case-Control Studies

Female

Humans

Infant

Infant

Low Birth Weight

Infant

Newborn

Infant

Premature

Logistic Models

Male

Odds Ratio

Posture

Pregnancy

Pregnancy Complications

Prone Position

Risk Factors

Scandinavian and Nordic Countries

Sleep

Sudden Infant Death

epidemiology

Publication and Content Type

ref (subject category)

art (subject category)