Adverse birth outcomes in alcohol-exposed pregnancies with or without tobacco and cannabis

To examine the risk of preterm birth (PTB) and small for gestational age (SGA) infants among pregnant persons with alcohol use diagnoses, alone or with comorbid cannabis or tobacco use diagnoses.

Data from California birth certificates (2007-2021) were linked to maternal/infant hospitalization records. Maternal ICD 9-10 codes indicated substance use diagnoses. We calculated the adjusted risk ratios (aRR) and 95 % confidence intervals (CIs) of extreme/very PTB (<32 weeks' gestation), late PTB (32-36 weeks), and SGA (<10th centile for birth weight) among those with alcohol alone versus alcohol with tobacco and/or cannabis use diagnoses.

Compared to alcohol alone, co-occurring alcohol and tobacco were associated with higher risks of extreme/very PTB (aRR = 1.44, 95 % CI = 1.09, 1.89), late PTB (aRR = 1.25, 95 % CI = 1.12, 1.40), and SGA infants (aRR = 1.31, 95 % CI = 1.19, 1.44). Individuals with alcohol and cannabis were at increased risk of SGA infants (aRR = 1.21, 95 % CI = 1.05, 1.38). Those with indications of all three substances had higher risk of extreme/very PTB (aRR = 1.68, 95 % CI = 1.17, 2.40) and SGA infants (aRR = 1.29, 95 % CI = 1.13, 1.48).

Among those with an alcohol diagnosis, prenatal co-exposure to tobacco with or without cannabis was associated with increased risk of PTB and SGA relative to alcohol alone. Screening for and addressing prenatal polysubstance use should be prioritized.