Sudden unexplained and unexpected death in twins has not been well studied, particularly in relation to the common practice of sleeping twin infants together in the same cot (cobedding). Postal surveys of 109 mothers of twins were undertaken when the infants were 6 weeks, 4 months, and 8 months of age to determine the prevalence of cobedding, infant care practices related to sudden infant death syndrome (SIDS), and the mother's knowledge of SIDS risk factors. SIDS risk factor knowledge was similar to an earlier survey of singletons in 2005. At 6 weeks, 76% of infants usually slept on the back; this changed to 86% at 4 months and 73% at 8 months. At 6 weeks, 52% usually cobedded with their twin all or part of the time. At 4 and 8 months, this had reduced to 31% and 10%, respectively. Side-by-side cobedding configurations were predominant at 6 weeks, with feet-to-feet configurations increasing as the infants grew older. Breastfeeding was reported in 83%, 61% and 31% of infants at 6 weeks, 4 months and 8 months, respectively. Pacifier use was reported in 38%, 50% and 33% at the respective surveys. As the age of the twins increased, mothers were significantly more likely to be concerned about deformational plagiocephaly in Twin 1 than in Twin 2.
Conclusion: Despite a lack of evidence of the risks or benefits of cobedding, this practice was very popular, especially in the younger infants. More research is needed to establish the safety of cobedding in relation to the risk of SIDS.