Does Birth Month Play a Role in BMD Later in Life?

LIVERPOOL, ENGLAND — Maternal exposure to sunlight in late pregnancy can have a beneficial influence on the offspring's bone mineral density in later life, Dr. Nicola J. Goodson said at the annual meeting of the British Society for Rheumatology.

“In the United Kingdom, the main dietary sources of vitamin D are fish and fortified margarine, but more than 90% of the vitamin is obtained by casual exposure to the sun, and because of the latitude the majority of the population is vitamin D deficient for much of the year,” said Dr. Goodson of University Hospital Aintree, University of Liverpool (England).

Birth records and dual-energy x-ray absorptiometry (DXA) scan results were examined for 15,042 women and 2,160 men from the Morecambe Bay catchment district. The mean age was 62 years.

At the latitude of this district, 54 degrees north, the months with adequate sunlight are May through September. Patients therefore were categorized as having infant sunlight exposure if their birth months were between March and September and they could be expected to have at least 1 month of exposure to ultraviolet B light in the first 3 months of life. They were classified as antenatal exposure if their birth months were between May and November and they had at least 1 neonatal month of exposure to sunlight, said Dr. Goodson.

Overall, 51% of patients had BMD in the normal range. As expected, women had lower mean T scores, at −1.7, than did men, at −0.91, she said.

Analysis of sunlight exposure in the first 3 months of life and normal BMD, after adjustment for age at the time of the DXA scan, found no significant association, with an odds ratio (OR) of 1.

In contrast, for those categorized as antenatal exposure, there was a modest association with normal bone mineral density in adulthood, with an OR of 1.16, Dr. Goodson said. Those patients who had antenatal sunlight exposure also were likely to have osteopenia or osteoporosis: Those who were osteopenic had a 12% reduced odds of antenatal exposure and those who were osteoporotic had a 19% reduced odds of antenatal exposure, she said.

These associations were only seen among women.

In a separate analysis for those whose DXA scans were done before age 50, there was no association of early life sunlight exposure in either men or women. However, in these younger patients there was a very strong association of early life, rather than antenatal, exposure with osteoporosis. “Those patients in the osteoporotic range had a 49% reduced odds of having a birth month that enabled antenatal exposure to UVB,” she said.

In summary, she said, adult BMD was associated with birth month in this unselected DXA cohort.

“Maternal vitamin D levels should be optimized, particularly during the third trimester, either by diet or by safe UV exposure,” Dr. Goodson said.

LIVERPOOL, ENGLAND — Maternal exposure to sunlight in late pregnancy can have a beneficial influence on the offspring's bone mineral density in later life, Dr. Nicola J. Goodson said at the annual meeting of the British Society for Rheumatology.

“In the United Kingdom, the main dietary sources of vitamin D are fish and fortified margarine, but more than 90% of the vitamin is obtained by casual exposure to the sun, and because of the latitude the majority of the population is vitamin D deficient for much of the year,” said Dr. Goodson of University Hospital Aintree, University of Liverpool (England).

Birth records and dual-energy x-ray absorptiometry (DXA) scan results were examined for 15,042 women and 2,160 men from the Morecambe Bay catchment district. The mean age was 62 years.

At the latitude of this district, 54 degrees north, the months with adequate sunlight are May through September. Patients therefore were categorized as having infant sunlight exposure if their birth months were between March and September and they could be expected to have at least 1 month of exposure to ultraviolet B light in the first 3 months of life. They were classified as antenatal exposure if their birth months were between May and November and they had at least 1 neonatal month of exposure to sunlight, said Dr. Goodson.

Overall, 51% of patients had BMD in the normal range. As expected, women had lower mean T scores, at −1.7, than did men, at −0.91, she said.

Analysis of sunlight exposure in the first 3 months of life and normal BMD, after adjustment for age at the time of the DXA scan, found no significant association, with an odds ratio (OR) of 1.

In contrast, for those categorized as antenatal exposure, there was a modest association with normal bone mineral density in adulthood, with an OR of 1.16, Dr. Goodson said. Those patients who had antenatal sunlight exposure also were likely to have osteopenia or osteoporosis: Those who were osteopenic had a 12% reduced odds of antenatal exposure and those who were osteoporotic had a 19% reduced odds of antenatal exposure, she said.

These associations were only seen among women.

In a separate analysis for those whose DXA scans were done before age 50, there was no association of early life sunlight exposure in either men or women. However, in these younger patients there was a very strong association of early life, rather than antenatal, exposure with osteoporosis. “Those patients in the osteoporotic range had a 49% reduced odds of having a birth month that enabled antenatal exposure to UVB,” she said.

In summary, she said, adult BMD was associated with birth month in this unselected DXA cohort.

“Maternal vitamin D levels should be optimized, particularly during the third trimester, either by diet or by safe UV exposure,” Dr. Goodson said.

LIVERPOOL, ENGLAND — Maternal exposure to sunlight in late pregnancy can have a beneficial influence on the offspring's bone mineral density in later life, Dr. Nicola J. Goodson said at the annual meeting of the British Society for Rheumatology.

“In the United Kingdom, the main dietary sources of vitamin D are fish and fortified margarine, but more than 90% of the vitamin is obtained by casual exposure to the sun, and because of the latitude the majority of the population is vitamin D deficient for much of the year,” said Dr. Goodson of University Hospital Aintree, University of Liverpool (England).

Birth records and dual-energy x-ray absorptiometry (DXA) scan results were examined for 15,042 women and 2,160 men from the Morecambe Bay catchment district. The mean age was 62 years.

At the latitude of this district, 54 degrees north, the months with adequate sunlight are May through September. Patients therefore were categorized as having infant sunlight exposure if their birth months were between March and September and they could be expected to have at least 1 month of exposure to ultraviolet B light in the first 3 months of life. They were classified as antenatal exposure if their birth months were between May and November and they had at least 1 neonatal month of exposure to sunlight, said Dr. Goodson.

Overall, 51% of patients had BMD in the normal range. As expected, women had lower mean T scores, at −1.7, than did men, at −0.91, she said.

Analysis of sunlight exposure in the first 3 months of life and normal BMD, after adjustment for age at the time of the DXA scan, found no significant association, with an odds ratio (OR) of 1.

In contrast, for those categorized as antenatal exposure, there was a modest association with normal bone mineral density in adulthood, with an OR of 1.16, Dr. Goodson said. Those patients who had antenatal sunlight exposure also were likely to have osteopenia or osteoporosis: Those who were osteopenic had a 12% reduced odds of antenatal exposure and those who were osteoporotic had a 19% reduced odds of antenatal exposure, she said.

These associations were only seen among women.

In a separate analysis for those whose DXA scans were done before age 50, there was no association of early life sunlight exposure in either men or women. However, in these younger patients there was a very strong association of early life, rather than antenatal, exposure with osteoporosis. “Those patients in the osteoporotic range had a 49% reduced odds of having a birth month that enabled antenatal exposure to UVB,” she said.

In summary, she said, adult BMD was associated with birth month in this unselected DXA cohort.

“Maternal vitamin D levels should be optimized, particularly during the third trimester, either by diet or by safe UV exposure,” Dr. Goodson said.