Plant-Based Diets and Baby Growth: What a Major Study of 1.2 Million Infants Reveals

A groundbreaking study of 1.2 million Israeli infants reveals that babies from vegan families show distinct growth patterns compared to those from meat-eating households, with higher rates of underweight at birth but similar overall development trajectories. The research, published in JAMA Network Open, represents one of the largest investigations ever conducted on how family dietary choices affect infant growth during the critical first two years of life.

What Did This Massive Study Actually Find?

Researchers tracked 1,198,818 infants from birth through age two, comparing growth patterns across three family types: omnivorous (meat-eating), vegetarian, and vegan households. The study found that 7.2% of vegan family infants were underweight at their first medical visit, compared to 4.7% from omnivorous families and 5.7% from vegetarian families.

However, the differences weren't as dramatic as you might expect. By their final visit around 18 months, only 1.1% of vegan family babies remained underweight, compared to 0.8% from omnivorous families—a much smaller gap than at birth.

How Do Growth Patterns Differ by Family Diet?

The research revealed several key differences in how babies develop based on their family's eating habits:

• Birth Weight: Vegan family infants averaged 3.2 kg (7.1 pounds) at birth compared to 3.3 kg (7.3 pounds) for omnivorous family babies
• Length Development: Vegan family infants showed slightly slower length growth throughout the study period
• Weight Catch-Up: Despite starting smaller, vegan family babies showed similar weight trajectories after the first few months
• Overweight Rates: Interestingly, vegan family infants had lower rates of being overweight at birth (1.8% vs 2.4% for omnivorous families)

The study controlled for maternal age, gestational week, birth type, parity, breastfeeding duration, geographic-level income, and area-level ethnic composition to ensure the dietary patterns were the primary variable being measured.

What About Breastfeeding Patterns?

One striking finding involved breastfeeding patterns, which varied significantly across dietary groups. Among vegan families, 29.8% practiced full nursing (exclusive breastfeeding), with 65.3% of those continuing for 1-6 months, compared to 47.3% of omnivorous families who practiced full nursing initially. However, vegan families were more likely to continue some form of breastfeeding for extended periods—47.3% nursed for 12 months or more versus 27.4% of omnivorous families.

This pattern suggests that while vegan mothers may face different breastfeeding patterns initially, they tend to maintain nursing relationships longer than their omnivorous counterparts, potentially helping compensate for early growth differences.

Should Parents Be Concerned?

The research shows that while there are measurable differences in infant growth patterns, the vast majority of babies from all dietary backgrounds develop normally. The study found no significant differences in stunting rates between groups by the final visit, and overweight rates remained consistently low across all family types.

Importantly, the study tracked real-world families rather than controlled dietary interventions, meaning the results reflect how people actually eat rather than idealized plant-based nutrition. The vegan families in the study had older mothers (mean 33.0 vs 30.0 years) and higher geographic-level income scores, factors that typically support better health outcomes.

The findings suggest that with proper attention to nutrition during pregnancy and infancy, families following plant-based diets can support healthy infant development, though they may need to be more vigilant about ensuring adequate nutrition during the critical early months when growth is most rapid.