Accumulating evidence suggests that early-life nutrition can affect metabolism and thus increase the risk of disease in adulthood (e.g. type II diabetes and obesity). One possible mechanism to explain these effects is epigenetic variation at critical periods of development. Epigenetic variation describes non-inherited permanent alterations to an individuals DNA.

Recent work in mouse models has demonstrated that maternal nutritional status can affect such epigenetic processes such as DNA methylation and gene expression during embryonic development, with profound effects on outcomes. The investigators aim to study these processes in humans for the first time. The investigators will exploit the "experiment of nature" setting in The Gambia, i.e. fluctuation in diet according to season. During the 'hungry' season diets are known to be depleted in nutrients required for epigenetic gene regulation. Nutritional biomarkers in blood as well as the dietary intake will be measured in pregnant women according to season. A blood sample will also be taken from babies born to these women to determine whether there is a direct effect of diet on mothers' nutritional status and hence variation in DNA methylation patterns in their babies by season.

Inclusion criteria women:

- women aged 18-45 years on 15th March 2009, resident in West Kiang

Exclusion criteria women:

• on contraception
• confirmed pregnancy at recruitment
• enrolment in any study other than the ENID (Early Nutrition and Immune Development) trial (ISRCTN49285450)
• suffering from severe anaemia (haemoglobin <7 g/dl) or known sickle cell disease

Inclusion criteria infants:

- born to the above women

Exclusion criteria infants:

- those known to be severely malnourished (weight-for-height Z-score < -3)

women of reproductive age in rural Gambia and their infants