It might have been hearing your sister's blood-curdling screams when she went through 12 hours of labour.
Or perhaps it was those episodes of Grey's Anatomy that covered every possible horrific complication that could arise from childbirth. Maybe it's just the rough calculations you've done: how can something so big get pushed out of an opening so small?
Childbirth doesn't carry the risks it did a century ago, but plenty of women are still utterly terrified of the process - a fear known as tocophobia. A recent study conducted by researchers at the Department of Obstetrics and Gynecology at the University Hospital in Linköping, Central Sweden found women who fear childbirth are more likely to have a C-section (16.5 per cent) than women who don't (9.6 per cent) .
They had increased rates of both elective C-sections and emergency ones, even if they were scheduled for a vaginal delivery.
For some women, psychological counselling isn't enough to calm what are common initial fears of delivery. Some suggest exposure to graphic childbirths in popular media and a desire among women to exert more control over their lives (and schedules) has contributed to fears .
In an interview with ABC, New York reproductive psychiatrist Catherine Birndorf says she has treated patients who insisted on C-sections with full anesthesia so they would not be "present" for the delivery and others who feared the anesthesia itself and had to be slowly introduced to the operating room.
Have you or your partner suffered from fear of childbirth? Would you ever schedule an elective C-section to avoid the perceived trauma of vaginal delivery?