Improved survival of very preterm newborn population during the last decades has challenged us neonatologists to study and improve nutritional practices including vitamin D (VitD) supplementation. However, long term outcome in this aspect has not been researched in well documented preterm populations. As VitD has receptors in almost all human cells it modulates growth of many organs. Therefore I start to assess VitD supplementation practices and later health outcome (bones, teeth, muscles, heart, lungs) in two preterm population cohorts cared in Oulu University Hospital at the age of 5 years and 24 years (born 2014-2017 and 1994-1997).

Goals:

• To investigate the impact of VitD and mineral supplementation and biochemistry in infancy on health outcomes at the age of 5 years in childhood (bones, teeth, muscles, heart, lungs) after preterm birth (Preterm Child group)
• To investigate the impact of VitD and mineral supplementation and biochemistry in infancy on health outcomes at the age of 24-25 years in adulthood (bones, teeth, muscles, heart, lungs) after preterm birth (Preterm Adult group)

Subjects:

• Preterm Child group; Children, who were born prematurely before before 32 gestation weeks and before 34 gestation weeks with very low birth weight (VLBW, < 1500g) in Oulu University Hospital and/or cared in Neonatal Unit with VitD concentration measured before discharge during the years 2014 to 2017.
• Preterm Adult group; Adults, who were born prematurely before 32 gestation weeks and before 34 gestation weeks with very low birth weight (VLBW, < 1500g) in Oulu University Hospital and/or cared in Neonatal Intensive Unit during the years 1994 to 1997. For power calculation, the amount of participants for the adult group was done by estimating the inadequately low vitamin D concentration (< 50 nmol/l) to be found in 28 % of preterm born adults. (In Northern Finnish birth cohort 28 % at the age of 31 had serum 25-OH vitamin D concentration < 50 nmol/l in 1997). With the estimation of supplementation to decrease the percentage of participants with low vitamin D to 9 %, the required amount of participants would be minimum of 56 per group. Furthermore, if the level after supplementation is estimated to be low only in 2,8 %, the amount would be required as 29 cases per group.

Methods in protocol:

At the first visit and in the end of intervention; measurements of length, weight, head circumference, waist-to-hip ratio will be done; muscular power is assessed by grip test of both hands; lung function test with bronchodilatation is done at the first appointment; heart ultrasound, blood pressure measurement and bicycle stress test with a circadian electrocardiography will be done in the beginning and at the end; bone mineralisation will be measured by dual energy x-ray absorptiometry (DXA) and ultrasound methods; VitD concentration will be measured 4 months interval during the follow up. The control peers participate only the first visit. The child group will be assessed only once and without bicycle stress test.

Inclusion Criteria:

• preterm and term born adults at the age of 22-25
• preterm born children at 5 years

Exclusion Criteria:

- motor disability

Healthy preterm born children and young adults. Tern born young adults as controls for the adult group.