Collectively , the evidence suggests that higher serum levels of 25(OH)D are associated with a reduced risk of asthma exacerbations , but there was little evidence to suggest an association with asthma incidence , prevalence or severity .
Asthma is a major public health issue .
The co-occurrence of the high prevalence of asthma and vitamin D deficiency documented globally in recent decades has prompted several investigations into a possible association between the two conditions .
The objective of this paper was to synthesize the evidence from studies that have measured the association between serum vitamin D  and asthma incidence , prevalence , severity and exacerbations .
Maternal vitamin D status during pregnancy and child outcomes
Objective : To investigate whether exposure to high maternal concentrations of 25(OH)-vitamin D in pregnancy poses any risk to the child . Design : Prospect i ve study . Setting : Princess Anne Maternity Hospital , Southampton , UK.Subjects : A group of 596 pregnant women were recruited . A total of 466 ( 78 % ) children were examined at birth , 440 ( 74 % ) at age 9 months and 178 ( 30 % ) at age 9 years . Methods :  Maternal 25 (OH)-vitamin D concentrations  were measured in late pregnancy . Anthropometry of the child was recorded at birth , 9 months and 9 years . At 9 months , atopic eczema was assessed . At 9 years , children had an echocardiogram and a dual energy x-ray absorptiometry scan , blood pressure , arterial compliance and carotid intima-media thickness were measured and intelligence and psychological function assessed . Results : There were no associations between maternal 25(OH)-vitamin D concentrations and the child 's body size or measures of the child 's intelligence , psychological health or cardiovascular system . Children whose mothers had a 25(OH)-vitamin D concentration in pregnancy > 75 nmol/l had an increased risk of eczema on examination at 9 months ( OR 3.26 , 95 % CI 1.15–9.29 , P=0.025 ) and asthma at age 9 years ( OR 5.40 , 95 % CI , 1.09–26.65 , P=0.038 ) compared to children whose mothers had a concentration of < 30 nmol/l . Conclusion : Exposure to maternal concentrations of 25(OH)-vitamin D in pregnancy in excess of 75 nmol/l does not appear to influence the child 's intelligence , psychological health or cardiovascular system ; there could be an increased risk of atopic disorders , but this needs confirmation in other studies .Sponsorship : The study was supported by the Medical Research Council and WellChild ( previously known as Children Nationwide )
Collectively , the evidence suggests that higher serum levels of 25(OH)D are associated with a reduced risk of asthma exacerbations , but there was little evidence to suggest an association with asthma incidence , prevalence or severity .
Asthma is a major public health issue .
The co-occurrence of the high prevalence of asthma and vitamin D deficiency documented globally in recent decades has prompted several investigations into a possible association between the two conditions .
The objective of this paper was to synthesize the evidence from studies that have measured the association between serum vitamin D  and asthma incidence , prevalence , severity and exacerbations .