Pregnant women may be able to control to a degree when they give birth a new study has shown, and the most unfavourable day of the year is Halloween.

Research by the Yale School of Public Health has found that symbolism and superstition can affect childbirth rates as the study drew on birth certificate information across an 11-year period and found that there was a 5.3 percent decrease in spontaneous births and a huge 16.9 percent decrease of elected caesarean births on Halloween.

Previously it was thought that a woman was unable to influence the birth date of their child, but this study shows that the symbolism of Halloween being connected to death and horror can in some way encourage women to cross their legs on that day.

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In contrast, the idea that Valentine's Day symbolises peace, love and togetherness was shown as the most favourable day to give birth. The study showed a 3.6 percent increase in spontaneous births and 12.1 percent increase in caesarean births.

"The study suggests that beliefs arising from our culture can have a greater impact on physical functioning than we might suspect," says Becca Levy, lead author and associate professor of epidemiology and psychology at Yale.

The report published in the Journal of Social Science and Medicine considered that women's hormones, may be causing them to 'choose' the onset of the birth.

The findings may have even been even more significant if it weren't for the many people that find Halloween to be a lucky and happy occasion.

In other news, findings by the Huntingdon Reproductive Medicine Centre in Brazil have shown that like women, men also have a biological clock.

The study by the Huntingdon Reproductive Medicine Centre in Brazil, was presented to the annual conference of the American Society for Reproductive Medicine in Florida this week, in which the study of 570 IVF treatments, of eggs donated by young healthy women as they measured the success rate of men of various ages conceiving and taking the baby to full term.

It was found that the chance of a man conceiving dropped by 7 percent each year between the ages of 41 and 45, and the percentage increases for again men older than 45.

Lead researcher Dr Paula Fettback, of the Huntingdon Reproductive Medicine Centre in Brazil said, "As a growing number of men are choosing to father children at older ages, comprehending the impact of male age and sperm quality has become incredibly important in public health."

Do you have a child born on Halloween? Tell us your story below.

Related video: How to paint a Halloween pumpkin design on a pregnant tummy.