TL;DR
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A South African longitudinal study found that infants exposed to both alcohol and tobacco during pregnancy had greater differences in facial size, shape and growth than infants exposed to either substance alone or neither. The findings were based on 634 infants with scans at 1 month and 1 year; they show an association, not proof that the combined exposures caused the differences.
A South African longitudinal study found that infants exposed to both alcohol and tobacco during pregnancy had greater differences in facial size, shape and growth than infants with no exposure or exposure to either substance alone. Researchers used 3D facial scans at 1 month and 1 year; the findings are associations and do not establish that co-exposure caused the observed differences.
Michael Suttie, PhD, of the University of Oxford, and colleagues analyzed data from the Safe Passage Study, a prospective cohort of more than 7,000 pregnancies in low-income communities in Cape Town, South Africa. Their analysis focused on 634 infants who had usable facial imaging at both ages and prenatal exposure information. The findings were reported in the journal Pediatrics.
The infants were grouped by reported prenatal exposure. There were 150 with continuous exposure to both smoking and alcohol, alongside groups with no exposure, continuous alcohol only, continuous smoking only, or continuous smoking with some alcohol use. Researchers assessed substance use through interviews at prenatal visits, recording frequency and quantity. They defined continuous exposure as exposure in the first trimester and at least one later trimester.
Combined exposure was associated with smaller facial size and greater overall facial dysmorphism than no exposure or single-substance exposure. The strongest overall difference was found at 1 month, although a difference remained statistically significant at 1 year. The single-exposure groups did not differ from controls on the reported facial-size measure. The researchers also found consistent midline displacement and greater outward movement of the inner corners of the eyes in the co-exposed group at both scan ages.
Some patterns differed by sex. Among girls, combined exposure was associated with greater reductions in facial growth and measurements around the eyes; the researchers reported that growth had not caught up by age 1 among girls exposed continuously to both substances. Among boys, co-exposure was linked to reduced nasal growth and smaller noses at 1 year. These are group-level study findings, not a way to predict an individual infant’s development.
Why Combined Exposure Matters
The findings add evidence that alcohol and tobacco exposure together may be associated with more pronounced craniofacial differences than exposure to either substance alone. The researchers said the results support efforts by clinicians and health authorities to address both smoking and alcohol use during pregnancy, rather than treating them as separate risks.
The study authors described a possible biological explanation: both substances may disrupt neural crest cells, which contribute to facial development, while nicotine-related effects on oxygen and nutrient delivery could add to alcohol-related disruption. That explanation is a proposed mechanism, not something this study directly tested. The research also does not establish whether the measured facial differences lead to health or developmental problems later in life.
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How Researchers Measured Infant Faces
The research draws on the Safe Passage Study, which enrolled more than 7,000 pregnancies. The current analysis was much smaller because it included only infants with both 3D facial scans—at about 1 month and 1 year—and relevant prenatal exposure data. Researchers excluded pregnancies involving reported illicit drug use, including marijuana, and infants with genetic diagnoses.
Alcohol and tobacco are recognized as potential hazards during pregnancy, and prior research has linked prenatal exposure to each with developmental risks. This study specifically examined whether their effects on facial development might be greater when exposure occurred together. Its findings apply to the selected group studied in Cape Town; the authors cautioned that results may not generalize to populations with different genetic backgrounds.
“Findings highlight tobacco’s potentiating effect on alcohol-related craniofacial harm.”
— Michael Suttie, PhD, and colleagues
Limits of the Evidence
The results show an association, not proof of causation. The analysis does not establish that alcohol and smoking caused the facial differences, or that their effects combine in a particular biological way. Researchers also noted possible influence from maternal nutritional deficiencies, the practical challenge of scanning infants while asleep, and uncertainty about whether findings from this Cape Town cohort apply to other populations.
The analysis included 634 infants from a much larger cohort, so the findings reflect the subset with the required scans and exposure data. The report does not establish the long-term significance of the measured differences, provide a clinical threshold for concern, or show whether the observed facial patterns predict later outcomes. The reported sex-specific patterns should also be interpreted as findings in this sample, not as individual predictions.
Further Study and Pregnancy Support
The researchers called for clinicians and health authorities to emphasize the potential risks of concurrent alcohol and tobacco use during pregnancy. The study report does not identify a planned follow-up trial or a specific next research milestone. Further work would be needed to test whether the associations hold in other populations, clarify how exposure timing and amount relate to facial development, and examine longer-term outcomes.
For now, the study adds to evidence on prenatal co-exposure but does not change the limits of what can be inferred from an observational analysis. Individual medical questions about alcohol or tobacco use during pregnancy should be discussed with a qualified healthcare professional.
Key Questions
What did the study find?
Among 634 infants with prenatal exposure data and 3D scans at 1 month and 1 year, combined exposure to alcohol and tobacco was associated with greater facial-size, shape and growth differences than no exposure or exposure to either substance alone.
Does the study prove that alcohol and smoking caused the differences?
No. The research found an association in an observational study. It cannot establish that the substances caused the differences or rule out other contributing factors.
Were the findings the same for boys and girls?
The reported patterns differed by sex. Girls with continuous co-exposure showed greater reductions in facial growth and measurements around the eyes, while boys showed reduced nasal growth and smaller noses at 1 year. These group findings do not predict an individual child’s development.
Do the results apply to all pregnant people and infants?
That is unclear. The analysis came from a selected group in Cape Town, South Africa, and the authors said generalizability to populations with different genetic profiles is uncertain.
What should readers take away from the findings?
The researchers said the results support attention to both smoking and alcohol exposure during pregnancy. The study is not medical advice or a diagnostic tool; questions about pregnancy and substance use should be discussed with a qualified healthcare professional.
Source: medpagetoday.com
