Pregnancy may significantly increase the risks of car accidents, according to a new research published in the Canadian Medical Association Journal. “The reason for the link is not completely clear, but [study author Donald] Redelmeier speculated that during the second trimester, women may develop a false sense of security that is often compounded by insomnia, back pain and a more hectic life in general,” Fox News reported Tuesday.

“The study looked at more than 500,000 women who gave birth during the study period of three years. During this time, these women were involved in nearly 7,000 car crashes that required hospitalization, including 757 crashes during the second trimester,” The Weather Channel continues. According to the new study, there was a 42% spike in crashes compared to other trimesters. The Weather Channel also notes that, although pregnant women are more likely to cause accidents than non-pregnant women, “Men of the same age still had a higher overall risk.”

The study author adds that he is not suggesting that pregnant women avoid driving altogether. Redelmeier does concede, however, that pregnant women should be especially careful. 

Some doctors are skeptical of Redelmeier’s study — and insist further research is necessary to draw a solid connection between pregnancy and crashes. First, emergency physician Sampson Davis points out that it doesn’t seem logical for the second trimester to be the most dangerous. The first semester is more often associated with nausea, dizziness, fatigue, and insomnia — all symptoms that would likely boost the risks of driving. Similarly, Davis argues, “The researchers did not account for all possible contributing factors, such as weather and other medical conditions.”