Increased exposure to the sun rays could help a woman have a baby, but it is the weather a month before conception that is key, not the weather at the time.
Speaking at European Society of Human Reproduction and Embryology’s annual conference in Lisbon, Belgian researcher Dr Frank Vandekerckhove, said higher temperatures, lack of rain and sunshine improved results through IVF fertility.
He said at a fertility conference: "In a world where reproduction is becoming increasingly medicalised, sunshine could be a simple way of boosting fertility."
Dr Vandekerckhove, o fUniversity Hospital Ghent's Centre for Reproductive Medicine, studied the IVF results of 6,000 women over a six-year period, and compared the dates of their treatment with weather conditions at the time.
He found the link with sunshine was the "most striking" and women were 35% more likely to have successful IVF treatments if they had been exposed to this weather a month before.
In the least sunny periods, successful treatments per cycle were 14%, and rose to 19% when the weather improved.
The doctor examined all outcomes, including number of eggs, rates of fertilisation, pregnancy and live births. All factors improved with sunny weather.
Dr Vandekerckhove said the increase in levels of vitamin D was a key factor in improving women's chances of getting pregnant, and this is made when sunlight hits our skin.
Although the study was completed with IVF patients, Dr Vandekerckhove said this could easily be applied to women who want to get pregnant naturally.
Professor Charles Kingsland, of the Hewitt Fertility Centre at Liverpool Women’s Hospital, said, according to the Telegraph: "We get bogged down and seduced into thinking that in order to get pregnant we need to be taking various pills, potions and creams to aid our fertility.
"Often all that is needed are the basics; namely, good diet, no smoking, reduction in alcohol, relaxation, sunshine and being happy and positive."