Women due to give birth in winter should use a sun lamp during the final three months of pregnancy to protect their child from osteoporosis in later life, doctors have suggested. They made their recommendation as research found that children born to mothers whose final three months of pregnancy included a summer month were 40% less likely to suffer the bone-wasting condition in adulthood. A mother's exposure to sunlight in that final period ensures the developing baby receives enough vitamin D to form strong bones. Doctors suggest that women whose last trimester of pregnancy does not fall between May and September should consider taking a holiday in the Mediterranean. As flying is not advised in the late stages of pregnancy, however, they suggest that women may need to settle for a sun lamp or vitamin D supplements. Dr Marwan Bukhari, a consultant rheumatologist at the Royal Lancaster Infirmary and author of the study presented to the British Society for Rheumatology, said: "You only get good sunlight (when you make vitamin D) between May and September in UK. Pregnant women should have vitamin D supplements or should have lots of good sunshine in somewhere like north Africa or the southern Mediterranean (in winter).' Bukhari added: "Sun lamps are an option. It needs to be the right kind of sun lamp to convert fat under the skin to vitamin D.' The doctors are not recommending sunbeds, which give a far higher dose of ultraviolet light than lamps. Bukhari and colleagues studied 17,000 patients. They found that patients under 50 were 40% less likely to have developed osteoporosis if their mother's last trimester of pregnancy included a summer month. SUNDAY TIMES, LONDON