Southern babies at risk of rickets

Researchers are calling for full Government funding of vitamin D and a change of health guidelines after a new study revealed South Island women and their babies are at high risk of deficiency.

The University of Otago study recruited 126 women through Dunedin’s Queen Mary Maternity Centre from 2011 to 2013. The study, published in the journal Nutrients yesterday, found 65 per cent of mothers and 76 per cent of infants had vitamin D deficiency, with evidence of rickets in three infants.

Vitamin D is essential for foetal bone health, growth and dental health, and a lack of it is associated with an increased risk of rickets in childhood, which causes soft bones and increases the risk of fractures and deformities.

The body produces the vitamin when the skin is exposed to UVB rays from the sun. But in the South Island especially, the sun might not produce enough UVB rays in winter for the body to produce vitamin D, which can also be found in eggs, liver and oily fish but most people do not consume them in high enough quantities.

Breast milk did not contain vitamin D, so infants who were exclusively breastfed were at risk of deficiency and should be offered drops, Wheeler said.

Formula is fortified with vitamin D; bottle-fed babies do not need a supplement.

Lead author Dr Ben Wheeler, of the Dunedin School of Medicine’s department of women’s and children’s health, said health policy was not effectively preventing vitamin D deficiency.

Most New Zealand women and their children would not meet the risk criteria to be prescribed supplements, he said.

Physicians are advised to ‘‘consider’’ vitamin D supplementation for pregnant women and breastfed infants who were considered ‘‘at risk’’ by having one or more of the following: dark skin; complete sun avoidance; a sibling with rickets; liver or kidney disease; and infants who are breastfed over winter.

The study showed that in the South Island traditionally low-risk women and their infants had ‘‘very high’’ rates of deficiency and some infants had ‘‘very severe deficiency’’, something not previously seen in other similar international studies.

It also found that women fitting the high-risk criteria were not necessarily offered the supplement.

One of the study’s participants, who asked not to be named to protect her children’s privacy, said she was never offered supplements throughout her two pregnancies despite being at high risk because of her dark skin.

She breastfed her two children exclusively until they were about five months old, but was never offered vitamin drops for them either, she said.

A blood test around her daughter’s first birthday revealed she had an ‘‘unreadably low’’ level of vitamin D.

‘‘If it hadn’t been for the study, we might not have realised she had low vitamin D levels until she had a fracture or rickets.’’

She said she knew another study participant whose child had low results and who suffered two fractures from low-force impacts by the time she started school.

‘‘Supplements should be offered to every pregnant woman, just like folic acid, because we all get busy and don’t necessarily think of asking for it,’’ she said.

European countries, the United States and Canada offered funded vitamin D to all pregnant women and New Zealand should do the same, Wheeler said.

A funded pregnancy formulation including vitamin D, folic acid and iodine would be ideal, he said.

Breastfed infants should also be offered a single-drop supplement, which was much easier to use than the funded option requiring parents to give their babies 10 drops daily.

According to the Health Ministry, about 5 per cent of Kiwi adults are vitamin D deficient and 27 per cent are below recommended blood levels. It could not answer questions about the study by deadline.