Natty
a) that article comes from a US site. US sites will tell you it isn't safe to drink herbal tea, use OTC medications that are considered safe in Europe, eat ham.
In fact, another page from that site you linked to says "Whether you should be lifting during pregnancy or not is a question for your healthcare provider, but the general rule of thumb is let someone else do it for you.
Women who are at risk for premature labor may need to stop lifting objects after the first trimester."
So there you go, parents of toddlers. Don't lift them after 12 weeks 
americanpregnancy.org/is-it-safe/lifting-pregnancy/
There is also a difference between something that isn't proven to be dangerous, and is proven to be safe. They aren't one and the same, which is why lots of OTC meds will say not to be taken when pregnant. Not because there is any suggestion that they are dangerous, but because it can't be proven they are safe, as to do so would mean a medical trial involving pregnant women and that would be unethical.
By the same logic, there is no safe amount of orange juice to drink, because an absence of studies showing danger does not automatically mean something is safe.
What is absurd is that on that same stupid american site, it gives advice about the use of hair dyes, and says that because studies show little risk, that means they are safe. So they are applying a very inconsistent logic.
As the author of 'Expecting better' summed up much better than I can, the studies used to justify the 'drink zero alcohol' are deeply flawed and have very little scientific basis as they are based on self-reporting and don't take into account other things the women are doing, including drug taking.
Obviously there are always people who say 'why take ANY unnecessary risk', but I find they are generally people who are totally unable to quantify or understand risk