Maternal obesity linked to increased risk of sudden unexpected infant death

Maternal obesity linked to increased risk of sudden unexpected infant death | Image Credit: © alekseyvanin - © alekseyvanin - stock.adobe.com.

There is an increased risk of sudden unexpected infant death (SUID) among infants born to mothers with obesity, according to a recent study published in JAMA Network Open.1

Multiple adverse outcomes have been linked to maternal obesity, such as preterm birth, stillbirth, neonatal intensive care unit admission, and congenital anomalies. Additionally, the risk of all-cause infant mortality is increased by a higher maternal body mass index (BMI).

The prevalence of prepregnancy obesity has increased over time, with a rate of 32% among women aged 20 to 44 years reported in the United States between 2003 and 2006.2 During pregnancy, obesity is linked to gestational diabetes, hypertension, and preeclampsia.

Data evaluating the link between maternal prepregnancy obesity and SUID is lacking.1 Approximately 3500 SUID cases are reported in the United States per year, classified as either sudden infant death syndrome, ill-defined and unknown causes, or accidental suffocation and strangulation in bed.

Investigators conducted a nationwide cohort study to determine the link between maternal obesity and SUID. Data from 2015 to 2019 was obtained from the Centers for Disease Control and Prevention (CDC) National Center for Health Statistics. Infant deaths included mortalities within the first year of life.1

Births at 28 weeks’ gestation or later were included in the analysis, with SUID including death at 7 days postpartum or later. Prepregnancy maternal BMI was the primary exposure of the analysis.

BMI categories included underweight, normal weight, overweight, class 1 obesity, class 2 obesity, and class 3 obesity. These were classified as under 18.5, 18.5 to 24.9, 25 to 29.9, 30 to 34.9, 35 to 29.9, and 40 or higher, respectively.1

Maternal covariates included maternal age, race and ethnicity, birthplace, education, smoking status, and marital status. Additional covariates included paternal age and race, payment source for birth procedure, live birth order, and infant sex.

There were 18,857,694 live births included in the analysis, with a median maternal age of 29 years and a median gestational age of 39 weeks. The SUID rate was 0.88 per 1000 live births.1

An increased risk of SUID was observed among underweight mothers as well as those who were overweight or obese. However, the increased risks for underweight and overweight patients were no longer significant after adjusting for covariates.

Statistically significant increases in SUID remained for infants of all mothers in the 3 obese BMI categories, with an adjusted odds ratio (aOR) of 1.10 for class 1 obesity, 1.20 for class 2 obesity, and 1.39 for class 3 obesity. The risk of SUIDs was increased by nearly 30% among mothers with class 3 obesity vs those with normal BMIs.1

Shorter gestational periods were also linked to increased odds of SUID, with an aOR of 2.84 for 28 to 31 weeks and 1.93 for 32 to 36 weeks. However, the aORs for BMI categories did not significantly change when adjusting for gestational age, indicating that gestational age does not mediate this association.

Increasing classes of obesity were also associated with increased odds of each respective cause of SUID. Approximately 5.4% of SUID cases were linked to obesity, indicating approximately 179 cases of SUID caused by obesity in the United States annually.

These results indicated a direct association between BMI and SUID risk. Investigators recommended further research investigate specific causal mechanisms for this association.1

References:

1. Tanner D, Ramirez J, Weeks WB, Lavista Ferres JM, Mitchell EA. Maternal obesity and risk of sudden unexpected infant death. JAMA Pediatr. 2024. doi:10.1001/jamapediatrics.2024.2455
2. Valsamakis G, Kyriazi EL, Mouslech Z, Siristatidis C, Mastorakos G. Effect of maternal obesity on pregnancy outcomes and long-term metabolic consequences. Hormones (Athens). 2015;14(3):345-57. doi:10.14310/horm.2002.1590