Based on a study analyzing 52 million pregnancies within 12 years, researchers found that couples who try to get pregnant at Christmas have a higher chance of success.
They also found out that it is not a good idea to try for a baby during the summer.
The study was conducted at by the Indiana University, led by pediatrician Dr. Paul Winchester. He said that mothers who conceive between December and January benefit the most from the high levels of sunshine they are exposed to during the last few months of their pregnancy.
This means they will get more vitamin D, which increases their chances of a healthy birth. Unfortunately for women who get pregnant in June, they might experience pregnancy problems because the season may expose them to a higher presence of pesticide pollution from the summer crop dusting, according to Winchester.
The study showed that there were more children born in September, those who were formed in December, than any other month. However, this could also be due to couples intentionally trying for a baby during the holiday.
So the team decided to focus on IVF couples and analyzed how many attempts it took for them to finally conceive. They looked into 433 764 IVF cycles and learned that those who started their IVF journey between December and February had a 4 percent more chance of conceiving a healthy baby than those who started in June.
During their presentation at the American Society for Reproductive Medicine, the team also questioned whether there is a link between a successful IVF pregnancy and the effects of vitamin D and seasonally used chemicals.
According to the team, they might have studied IVF cases, but Dr. Winchester said that it could also be the case with couples using the natural method. He added that in the olden days, women may also prefer getting pregnant in December and giving birth in September, when the crops are plenty and ready for harvesting, the sun is still shining, and the baby can prepare themselves for the cold month.
When Dr. Winchester looked into the figures from then 1900s, more children were born in March than in September. However, he said that the significant change in the timing of the birth rates could be due to the popular use of pesticides starting in the 1930s.
He suggested that women who live in the US or Europe should avoid the vulnerable month of June when trying to conceive.