"[The] book doesn't treat women like children," Geddes says. "It treats them like adults able to understand the evidence … I think there is too much preaching to women. [I'm] trusting women to make decisions for themselves." The idea for the book came from Geddes's own experience of impending parenthood and was driven by her own frustration at the lack of reliable material to draw upon as well as her own sense of scientific curiosity. From whether some pregnant women really eat coal to how stress during pregnancy can affect a developing baby, the book tests the accuracy of dozens of common beliefs. Geddes found that some of the most widespread opinions were not backed by much evidence. "One thing that struck me was there was this really common myth that babies can only focus on things 30 centimetres in front of their face," she says. "Actually babies can see - they can focus at any distance, they're just not very good at it, so they tend to over- or under-shoot, which is why sometimes babies look a bit cross-eyed." Geddes also discovered doubts about some of the information women are given about childbirth. Many are told, for example, that certain forms of pain relief increase the risks of medical interventions such as C-section or instrumental delivery.

In fact, the odds of this happening are nil to very low. "That made me really angry because women make decisions based on things like this," she says. In other cases, Geddes found ample evidence to support the accepted wisdom. Immediate skin-to-skin contact with newborns, for instance, is now widely practised - and for good reason. "There's some quite strong research that … it does promote breastfeeding and also seems to massively relax the baby and cut off the stress response after birth." We just need to worry less and focus on what a wonderful time it is. But not every example had a clear-cut answer. One of the challenges for Geddes was to weigh up conflicting evidence or, in some cases, find any research at all.

Despite the prevalence of morning sickness, for instance, little is known about its causes. "There's no real research," she says. "There are various theories around … but no one really knows for sure." Overall, Geddes hopes the book will allow parents-to-be to focus on the few things - such as avoiding large doses of alcohol - that really matter. "So much of what we're told we need to worry about during pregnancy and becoming a mother isn't really supported by that much evidence," she says. "We just need to worry less and focus on what a wonderful time it is and just enjoy it." Lucy Perry, the founder of Beer + Bubs childbirth education sessions for men and author of Cheers to Childbirth, says dealing with so many unknowns is one of the challenges for expecting parents. When it comes to the birth process, she advocates an "overprepare and then go with the flow" attitude, rather than the notion that labour is something you can fully control.