September 2024
Is maternal obesity a risk factor for sudden unexpected infant death?
By Melanie Hinze
An Australian expert suggests caution when interpreting the results from new research which claims that maternal obesity should be considered as a risk factor for sudden unexpected infant death (SUID).
Published in JAMA Pediatrics, the US nationwide cohort study included data from more than 18 million live births from the Centers for Disease Control and Prevention National Center for Health Statistics linked birth-infant death records for birth cohorts from 2015 to 2019.
Infants born to mothers with class 1 obesity (body mass index [BMI] 30.0 to 34.9 kg/m2) were found to have a 1.10 times increased risk of SUID. Infants born to mothers with class II obesity (BMI 35.0 to 39.9 kg/m2) had a 1.20 times increased risk of SUID, and infants born to mothers with class III obesity (BMI ≥ 40.0 kg/m2) had a 1.39 times increased risk of SUID.
The study authors reported that about 5.4% of the total SUID cases were attributable to maternal obesity, and that there was a dose-dependent association between increasing maternal BMI and SUID risk.
However, Dr Danielle Longmore, Clinician Scientist Fellow at Murdoch Children’s Research Institute, Melbourne, said that she believed the relationship between maternal obesity and SUID remained unclear despite this publication.
‘I have some reservations about interpreting the association and therefore the proposed causal relationships raised in this publication,’ she said.
‘Is it just maternal obesity that is driving the increased risk through a direct cause as is mentioned in the paper (e.g. bed sharing), or an indirect cause such as increased hypoxic stress due to maternal obstructive sleep apnoea (as discussed in the paper), or other indirect causes such as breastfeeding or more complex social factors that were not raised in this paper?'
Dr Longmore added that women with obesity were known to have greater difficulty initiating and sustaining breastfeeding, and in particular exclusive breastfeeding, which was known to be protective against SUID.
Dr Longmore also raised the question of whether maternal obesity was a proxy for social disadvantage in this analysis, despite adjustment for some measures of socioeconomic status. She noted that maternal obesity was more prevalent among women from lower socioeconomic backgrounds, as were lower rates of breast-feeding and higher rates of smoking and antenatal drug use, which could impact SUID risk.
‘The article did adjust for maternal education, ethnicity and payment source; however, further exploration of the social determinants of health would have been helpful’, she said.
‘Understanding the implications for a mother who experiences SUID and is obese is very important,’ said Dr Longmore.
‘SUID is a rare and devastating event,’ she said, adding, ‘It is essential that mothers are not made to feel guilty as most factors such as genetics and body size are not within their control.’
The authors of an accompanying editorial raised many of these issues and called for more research in the area.
Dr Longmore said that while more research was needed, she would not suggest GPs change how they educate and make recommendations for mothers living with obesity based on this publication alone.
‘I would suggest ongoing education regarding known protective practices to reduce risk for SUID,’ she said.