Before weaning, breast milk is the physiological form of neonatal nutrition, providing pups with all nutrient requirements. Maternal low-protein diet (LPD) during pregnancy and lactation induces adverse changes in key maternal organs, which have negative effects on pup development. We studied the effects of maternal LPD on liver weight, mammary gland (MG) cell differentiation, milk composition and production and pup development throughout lactation. We fed rats with control (C) or LPD (R) during pregnancy and lactation. At 7 d early, 14 d mid and 21 d late lactation stages, maternal biochemical parameters, body, liver and MG weights were analysed. MG cell differentiation was analysed by haematoxylin and eosin staining; milk nutrient composition and production were studied; pup body, liver and brain weights, hippocampal arachidonic acid (AA) and DHA were quantified. Results showed lower body and liver weights, minor MG cell differentiation and lower serum insulin and TAG in R compared with C. R milk contained less protein and higher AA at early and mid stages compared with C. R pup milk and fat intake were lower at all stages. R protein intake at early and mid stages and DHA intake at mid and late stages were lower compared with C. In R pups, lower body, liver and brain weights were associated with decreased hippocampal AA and DHA. We conclude that maternal LPD impairs liver and MG function and induces significant changes in maternal milk composition, pup milk intake and organ development.

Low vitamin D levels during pregnancy may account for reduced fetal growth and for altered neonatal development. The present study explored the association between maternal vitamin D status measured early in pregnancy and birth weight, prevalence of small-for-gestational-age (SGA) infants and postnatal growth (weight and length), as well as the potential role of vitamin D status in explaining ethnic disparities in these outcomes. Data were derived from a large multi-ethnic cohort in The Netherlands (Amsterdam Born Children and their Development (ABCD) cohort), and included 3730 women with live-born singleton term deliveries. Maternal serum vitamin D was measured during early pregnancy (median 13 weeks, interquartile range: 12–14), and was labelled ‘deficient’ ( ≤ 29·9 nmol/l), ‘insufficient’ (30–49·9 nmol/l) or ‘adequate’ ( ≥ 50 nmol/l). Six ethnic groups were distinguished: Dutch, Surinamese, Turkish, Moroccan, other non-Western and other Western. Associations with neonatal outcomes were analysed using multivariate regression analyses. Results showed that compared with women with adequate vitamin D levels, women with deficient vitamin D levels had infants with lower birth weights ( − 114·4 g, 95 % CI − 151·2, − 77·6) and a higher risk of SGA (OR 2·4, 95 % CI 1·9, 3·2). Neonates born to mothers with a deficient vitamin D status showed accelerated growth in weight and length during the first year of life. Although a deficient vitamin D status influenced birth weight, SGA risk and neonatal growth, it played a limited role in explaining ethnic differences. Although vitamin D supplementation might be beneficial to those at risk of a deficient vitamin D status, more research is needed before a nationwide policy on the subject can be justified.