Also, the odds of conception are often low - some women take months or years. So like sex selection or sex determination, it looks like it works often enough just by chance that the urban legend may get credence by luck. (Sort of like “pulling out” - you may think you’re being careful and it turns out you’re just being lucky).
Apropos of nothing but I was under the impression that western alchemists’ search for a method of making gold was more to finance their searches for the philosopher’s stone or the universal solvent than an end in and of itself.
More importantly, will your poop rise in hot weather and shrink when it gets cold?
You’re thinking of something else.
I don’t think so. On most accounts (alchemists themselves were not very consistent about such things, never mind those who have written about them) the philosopher’s stone was the substance that they hoped to discover that, when applied to base metals, would turn them into gold. (It was sometimes held to be an elixir of life too, but, as I said, western, and Muslim, alchemists were less concerned with this issue than were Chinese ones.) You weren’t making gold to finance the search for the philosopher’s stone, you were trying to make the philosopher’s stone in order to make gold.
I am not sure why anyone would search for a universal solvent as an end in itself (anyway, what would you keep it in if you found it?!), although making it may have been thought, by some, to be a necessary step on the way to making the actual philosopher’s stone. I do not think that the search for the solvent was a particularly important aspect of the alchemical tradition as a whole. Paracelsus seems to have been particularly concerned with it, but he was late in the Alchemical tradition, and far from being a typical alchemist.
That said, alchemy was not just a matter of trying to make gold in order to get rich (although that was certainly part of it). It had a large spiritual, religious components, and even the interest in gold was not solely about gold’s monetary value, but also bound up with a notion of gold as the noblest, highest, most virtuous, and most spiritually perfect of substances. Gold was thought of as the Aristotelian “final cause” of metals: All other metals (and ores, etc.) were striving to be, and evolving towards being, gold, much as humans were, or should be, striving toward the spiritual perfection that would win them eternal life in heaven. Finding the philosopher’s stone was important (to many alchemists) because it would be sign that you were successfully spiritually perfecting yourself. As a bonus, it would make you rich too!
Qin’s burial complex was reported to include a huge scale map of China, with the rivers being represented by rivers of quicksilver. Archeologists believe that the site has recently been discovered, but they’re having trouble excavating it because all the mercury down there would kill them.
–Cliffy
I was told that some early gold miners used a shot of mercury as a type of hazing for new miners. Supposedly the mercury passed through the body very quickly, as in minutes.
Sorry, I was more generally answering the OP’s question than wondering whether it happened. People did (and do!) lots of things that don’t work in the name of health. 
Molten lead would certainly clean you out.