Somali migrant women, often in veiled clothing, living in a town in mid Sweden on the 60:th parallel were observed to be weak and to have a waddling gate.

Study 1 was carried out in the setting of an antenatal clinic administered from a primary care center in Borlänge, a Swedish middle-sized industrial town at the 60:th parallel in Sweden. The investigators chose an initial study period in late spring to reflect the effects of the dark season with little ultraviolet B radiation that affects vitamin D production. Study 1 was carried out in a short period of time. The recruitment was performed in a retrospective design in order to neglect the seasonal effects of ultraviolet B radiation. Study 1 was carried out in year 2010. It was a cross sectional baseline study of blood levels of vitamin D measured as 25-hydroxyvitamin D (25-OHD) and physical performance in 123 pregnant and new mothers from Somalia (n=52) and Sweden (n=71).

Study 2: Examines the results on muscular performance, i.e. grip strength and squatting ability, from intervention with advice and prescription of vitamin D3 and calcium for 10 months, in all the women from study 1 with 25-OHD levels <50 nmol/L or 50 nmol/L of 25-OHD.

Study 3: The recruitment to Study 1 also serves as recruitment for a cohort study on delivery outcome in birth protocols starting 2016.

Study 4: The aim is to study the emic perspective and lifestyle related to vitamin D and strength in the group of Somali women by focus interviews among the Somali women from above.

A possible fifth study will explore correlations between 25-OHD and pain distribution and pain parameters.

Inclusion Criteria:

• Pregnant or new mother from Sweden or Somalia living in Borlänge and registered the antenatal clinic in Borlänge maximally 21 months prior to study start.

Exclusion Criteria:

• Severe metabolic, medical or mental disease (ex. deranged type I diabetes or psychosis).