Vitamin D Half-life in Pregnancy and Lactation

Inclusion Criteria: All participants: * Currently resident in West Kiang and planning to stay for the next 5 months * Aged between 18 and 45 y Pregnancy: * \> 20 wk \< 30 wk pregnant (gestational age assessment by ultrasound) * Singleton fetus Lactation: * Breast feeding Exclusion Criteria: All participants: * Severe anaemia (haemoglobin \< 7 g/dL) (as per ENID protocol) * Known sickle cell anaemia * Known to be asthmatic or allergic to peanuts (already excluded from ENID) * Known history of liver, kidney, gut or malabsorption problems * Other chronic condition * On prescription medication * Taking vitamin D supplements (\> 200 IU/d) * Broken bone in last 3 y * Recent infection or illness (2 weeks prior to the start of a study period) * Reported onset of menopause (already excluded from ENID) * Malaria parasitemia (prior to study period) * Unable to consent Pregnant: * Pregnancy-related complications or on discretion of mid-wife * Known HIV positive Lactation: * Health problem of mother or infant that may affect feeding practices