Maternal smoking effects on infant growth

Area of Science:

• Pediatrics
• Nutritional Science
• Environmental Health

Background:

• Maternal smoking during lactation is prevalent, but its effects on breast milk composition and infant growth are not fully understood.
• Previous research has not conclusively determined the impact of maternal smoking on nutrient transfer and infant development via breast milk.

Purpose of the Study:

• To investigate the influence of maternal smoking on breast milk nutrient content.
• To assess the impact of maternal smoking on infant longitudinal growth rate.
• To evaluate cotinine levels in mothers and infants as biomarkers of smoking exposure.

Main Methods:

• Longitudinal study of 23 smoking (S) and 23 non-smoking (NS) mother-infant pairs from birth.
• Breast milk volume measured by deuterium dilution.
• Breast milk and infant hair nutrient analysis (zinc, copper, iron, cadmium) using atomic absorption (AAS).
• Cotinine levels assessed by radio-immuno-analysis (RIA).
• Infant anthropometry (birthweight, height, weight-for-height) and growth parameters (ZHA, ZWH) evaluated.

Main Results:

• Infant height and height-for-age (ZHA) were significantly lower in the smoking group.
• Weight-for-height (ZWH) was higher in infants of smoking mothers by the third month, linked to slower height growth.
• Maternal and infant cotinine levels were significantly higher in the smoking group.
• No significant differences in breast milk volume or zinc, copper, and iron content were observed between groups, except for higher cadmium levels in the smoking group's milk.
• Infant hair mineral content was higher in the smoking group.

Conclusions:

• Maternal smoking during breastfeeding affects infant height, potentially due to impaired nutrient bioavailability.
• Cadmium levels in breast milk are increased by maternal smoking.
• While some nutrients are unaffected, smoking-related factors negatively influence infant growth trajectory.