Babies born to obese mums are at ‘greater risk of sudden unexpected infant death’

HEALTHY babies born to overweight mums are more likely to die unexpectedly in the first year of life.

A study looked at rates of sudden unexpected infant death (SUID) - which is without an obvious cause.

It often happens when the baby is asleep, giving it the nickname 'cot death'.

Researchers at University of Washington looked at 18 million babies born in the US between 2015 to 2019, of which some 16,500 died of SUID.

Babies born to mum’s with a high BMI before pregnancy - and therefore during - were more likely to die suddenly than babies born to healthy-sized mums with a BMI of 18.5-24.9.

The odds increased with the mum’s BMI.

In mum with a BMI of 30 to 34.9, defined as obese, or over 40, defined as severely obese, the odds increased by 10 per cent and almost 40 per cent, respectively.

They researchers said maternal obesity may account for five per cent of SUID cases per year.

Therefore, if the risk were eliminated, it could have resulted in approximately 175 fewer SUID cases per year in the US.

They do not have an explanation for the link.

However, they discussed that obese mothers are more likely to have sleep apnoea, which is when breathing intermittently stops during sleep, causing snoring and choking sounds. 

This, they said, may restrict feotal growth in a similar way to maternal smoking (a known risk factor for SUID). 

It was also noted that other studies had suggested that maternal obesity increases SUID while bed sharing, but that the evidence for this is weak.

The authors wrote in the paper, published in JAMA Pediatrics: “Maternal obesity should be added to the list of known risk factors for SUID. 

“With maternal obesity rates increasing, research should identify potential causal mechanisms for this association.”

Around 200 babies in the UK and 3,500 in the US suffer SUID every year, making it rare.

It is known that infants born prematurely or with a low birthweight are at greater risk - complications that are more likely to occur in an overweight or obese pregnant mum.

Although the exact cause is not understood, parents can help prevent SUID with safe sleeping measures, such as putting a firm mattress in their cot and not sharing a bed with a baby if a parents smokes. 

Losing weight during pregnancy is not recommended by the NHS.

It says: "If you are obese, usually defined as having a body mass index (BMI) of 30 or above, and pregnant, do not try to lose weight during your pregnancy. It will not reduce the chance of complications and may not be safe.

"The best way to protect you and your baby’s health is to go to all your antenatal appointments. This is so your midwife, doctor and any other health professionals can help with any problems you might face and take steps to prevent or manage them."