A changed pregnancy diet moved fetal brain measurements, and femur length with it

Design

Randomised controlled trial of a food-delivery and behaviour-change intervention, Ecuador

Population

215 women randomised in the first trimester (111 intervention, 104 control)

Primary outcome

Fetal brain and bone growth on ultrasound between 21 and 35 weeks

Effect

Corpus callosum length +0.19 cm (95% CI 0.02 to 0.35); gangliothalamic ovoid height +0.15 cm (0.03 to 0.26); femur length -0.10 cm (-0.19 to -0.02)

Two hundred and fifteen women in the first trimester in Ecuador were randomised to usual care (n = 104) or to the Mikhuna intervention (n = 111): a weekly food delivery of 8 eggs, 500 g of fish and a range of sustainably sourced fruit and vegetables, from 12 weeks' gestation to birth, with behaviour change counselling encouraging dietary diversity and discouraging highly processed food. Ultrasound measurements of fetal brain and bone were taken at 12, 21 and 35 weeks, with follow-up at two weeks postpartum.

The intervention worked as a diet intervention: 74.5% of the Mikhuna group met the minimum dietary diversity threshold at the close, against 55.8% of controls (P = 0.004). Between 21 and 35 weeks, corpus callosum length was greater by 0.19 cm (95% CI 0.02 to 0.35) and gangliothalamic ovoid height by 0.15 cm (95% CI 0.03 to 0.26). At 35 weeks the corpus callosum Z score differed by 0.56 (95% CI 0.03 to 1.09). Femur length went the other way, shorter by 0.10 cm (95% CI -0.19 to -0.02) over the same interval, with a Z score difference of -0.21 (95% CI -0.42 to 0.00).

This is research-stage and should be described that way in clinic. It is a genuine randomised trial of a food-based intervention with measured structural outcomes, which is rare, but the outcomes are ultrasound dimensions rather than anything a child does. The femur finding deserves naming rather than burying: an intervention that increases one growth measurement and reduces another has not simply made babies grow better.

• Dietary diversity, not a supplement, was the intervention - eggs, fish, fruit and vegetables delivered weekly
• Do not translate this into advice to restrict any food group in pregnancy
• If a woman asks, describe the outcome as a brain measurement on scan, not as a developmental benefit
• The shorter femur length is part of the result and belongs in any summary of it
• Relevant to Indian antenatal counselling mainly as support for diversity over a single micronutrient focus

Why it matters

Maternal nutrition advice has rested on micronutrient supplements; this tests a whole dietary pattern instead.

Don't overread it

These are ultrasound dimensions, not neurodevelopmental outcomes - no child outcome was measured.

The statistics, in plain English

Several of these confidence intervals sit close to the boundary. The corpus callosum Z score interval runs from 0.03 to 1.09 and the femur length Z score from -0.42 to 0.00, meaning the data are compatible with effects ranging from negligible to substantial. When a trial reports many measurements and a handful reach significance at the margin, some of those are expected by chance alone. The dietary diversity difference - 74.5% against 55.8% - is the most solid number here, because it is a large difference in the thing the intervention directly targeted.

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