Is Co-Sleeping Really Unsafe?

Co-sleeping or co-bedding, where a parent brings an infant into a bed with them for sleep, is risky. The statistics show that. Here is the evidence and proven mechanisms by which having a baby in bed with you can, sadly, result in their death.

Nightmare of Sudden Infant Death Syndrome

It has been every parent’s worst nightmare for generations – finding their infant dead suddenly and unexpectedly. As a father of two, I remember the sleepless nights alternating between crying infants and complete silence, wondering if my boys were actually breathing. The fear is palpable.

As a pediatrician who has had to pronounce infants dead and as a member of the team in my county that reviews infant deaths, I have far too often seen the grief and confusion when that fear becomes a reality.

For centuries we’ve struggled to understand the cause of, and even define what Sudden Infant Death Syndrome (SIDS) is. Over the years, the fear SIDS (sometimes known as cot death or crib death) has spawned multiple attempts by researchers and device makers to develop products to prevent SIDS – including apnea monitors, sleep positioners, or wedges. None of these interventions have been demonstrated to reduce the risk of SIDS.

What has been shown to reduce an infant’s risk of SIDS is very simple and many parents aren’t aware of it. And that is to place your infant in a safe sleeping position. The combination of underlying risk factors and unsafe sleeping positions, often caused by co-sleeping, appears to be the culprit behind most deaths.

SIDS and SUID Research

Since a consensus conference in 1991, Sudden Infant Death Syndrome (SIDS) has been defined as a death of an infant under one year of age that cannot be explained. The SIDS label is only applied after after a thorough investigation, including an autopsy, scene investigation, and review of the medical and social histories.

SIDS is one type of Sudden and Unexpected Infant Deaths (SUID). The reasons why the authorities need to investigate when an infant dies unexpectedly include: ensuring no foul play was involved or whether or not a preventable genetic condition (like certain heart arrhythmias) occurred that impact future deaths in a family.

Manageable Risk Factors

The majority of infants who die from SIDS have underlying risk factors that can be addressed to reduce the risk of death. Some children are likely born with intrinsic and undetected brain stem abnormalities that make them more susceptible to sudden death. Despite risk-factor modification, these infants still may die.

Some researchers are looking into the role the inner ear plays in SIDS. But the research so far is in its preliminary stages.

Unfortunately for many families, approximately 5% of SIDS cases involve otherwise healthy infants with no underlying risk factors. But I’m going to focus on the 95% in this post because the majority of these deaths can be prevented.

Unsafe Sleeping Positions

Improved death scene investigations over the past 2 decades have shown us that most SUIDs are a result of infants being placed in unsafe sleep positions.

Improved examinations by death investigators and Child Fatality Review Teams have shown that for most infants who die of SIDS and a vast majority of infants who die of asphyxiation (also known as suffocation) or undetermined causes are found in an unsafe sleep position.

The Back to Sleep campaign started in the 1990s after studies showed that infants placed on their back to sleep had a reduced risk of dying from SIDS. Between 1992 and 2001 the Back to Sleep campaign reduced the risk of SIDS by over 50%.

Problems Involved with Co-Sleeping

Unfortunately, one of the worst sleep environments for a child is to co-sleep in an adult bed or, more specifically, co-bed.

We’ve designed adult beds to be comfy and welcoming for us at the end of a hard day, with pillows, blankets and soft mattresses. But these are all major asphyxiation risks for an infant not old enough to roll over or lift their head.

Asphyxia while co-sleeping can occur from 3 primary mechanisms:

  • the parent rolling over on the child and restricting breathing,
  • the child rolling or being rolled between the bed and a wall, or
  • a child suffocating on soft bedding like blankets or pillows.

Carbon Dioxide Poisoning

A simple lack of oxygen is not how most high-risk infants who asphyxiate while co-sleeping die. Most actually die from carbon dioxide poisoning, by regularly re-breathing in their own or their parents exhaled breath.

Any object near the mouth and nose of an infant can create an air pocket in which the exhaled air gets trapped. The infant then re-breathes air with a higher concentration of carbon dioxide. As the carbon dioxide level increases in the bloodstream and oxygen levels decrease, the infant is more likely to stop breathing and die.

These mechanisms for death can also occur in an adult bed without an adult and on other surfaces with an adult – like a couch. It is very easy for an infant to roll off the chest of a sleeping adult and get wedged between the parent and the side of the couch.

Fatality Statistics are Not Improving Enough

The number of total infant deaths has held firm since 1998 despite a drop in SIDS cases. This is due to an increase in the number of cases of Accidental Strangulation and Suffocation in Bed (ASSB), which quadrupled from 1984-2004.

The number of deaths in unsafe environments, like co-sleeping in adult beds, is staggering. A report out of Michigan in 2011 demonstrated that 83% of their infant deaths were a result of sleep related asphyxiation.

Even looking only at SIDS cases, well designed epidemiological studies have demonstrated there is an increased risk of SIDS from co-bedding by itself after controlling for other risk factors, such as family history and smoking.

Dubious Advice About Co-Sleeping Safety

Despite the overwhelming body of research showing the deadly risks of co-sleeping, many lactation consultants and some prominent anthropologists strongly believe co-bedding reduces the risk of death and increases the length of breastfeeding.

While co-sleeping may increase the length of breastfeeding and breastfeeding has been shown to independently reduce an infant’s risk of SIDS, the risks of sleeping in an adult bed outweigh the benefits gained by breastfeeding.

Many co-sleeping proponents claim that so long as the parent removes soft objects or strangulation risks from the bed (such as excessive throw pillows, heavy blankets or pillows and blankets with tassels) that co-bedding is safe. Unfortunately, these individuals have failed to understand the bigger picture and the lessons learned from Child Fatality Review.

Recommendations for Reducing Risks

The American Academy of Pediatrics has several recommendations for parents who want to reduce their infant’s risk of SIDS and SUIDs. In addition to placing your infant on their back to sleep in a crib or bassinet of their own:

  • Sleep the infant on a firm surface and avoid soft objects in the crib
  • Avoid exposure to tobacco smoke
  • Breastfeed
  • Room share without bed sharing (place the bassinette next to the adult bed).

The research is clear: Very few infants die alone, on their back, and in a safe crib, and the majority of deaths are preventable.

I understand why some parents may want to co-bed or find themselves unintentionally doing it. Co-sleeping can make parents feel closer to their infant. Co-sleeping also may make it easier for some parents to extend breastfeeding during the night and to get a little extra sleep.

As a parent, I understand the exhaustion parents feel in the first weeks and months of life. I’m not trivializing that. But the research is clear: Very few infants die alone, on their back, and in a safe crib, and the majority of deaths are preventable.

For more information on safe sleep go to:

This is an updated version of an article first published on June 23, 2015.