Along the same lines: Pregnant women and babies shouldn’t attend the funerals of family members. If you have to, you must be sure to call the baby by name before you leave, and let him/her know that it’s time to go. If you don’t, the child’s spirit will will stay with the loved one’s soul, instead of going with its own body. If the spirit and body end up too far apart, they won’t be able to reconnect and the baby will die.
The most obviously ridiculous one, which my wife had me do several times, was tying her wedding ring to a string and holding it over her belly. If it goes back and forth, it’s a boy, and if it goes in a circle, it’s a girl.
I’m still not too clear on the “no vacuuming while pregnant” thing, either. I mean, I know a pregnant woman should avoid really strenuous activity, but I don’t see anything all that demanding about gently pushing a vacuum back and forth in itself. My best guess is, the “no vacuuming” thing is really a way to help ensure that women don’t lift the heavy vacuum to get over/around things, and to avoid the possibility that they’ll try to move furniture, which actually would be a strenuous activity.
My grandmother told my mom this (my dad’s mom, not her own mom). She said, “Uh huh. And how am I supposed to get my shirts on?” Grandma didn’t have any reply. 
She also said to never tickle a baby’s feet; if you do, they won’t talk for the first year (possibly two years?)!
Along the same lines, don’t scare a pregnant woman or the baby will stutter.
Don’t lift heavy things, don’t vacuum, don’t raise your arms above your head, don’t leave the house for a month after the birth…I’m sensing a pattern here that gives me a clue as to where these started. 
Right.
HONEY! My doctor said that folding laundry is a big giant no no, the static can get…into the…tubules…of the thingee and…JUST DO IT.
Placenta stew, anyone? BLECH!!!
Some lunatics where I work – dare I refer to them as cow-orkers – pee on a cup of Draino and then do something with the results to determine the sex of the baby.
Is it one of these?
Actually, that one sort of does work only not as an indication of the baby’s gender.
Tie something heavy to a string (ring or anything to act as a weight really) and hold it… anywhere really. Above the table will do fine. Think of a boy, it swings back and forth… think of a girl, it swings in a circle. I read about it in a magic book, and tried it several times myself. I thought it was kinda cool actually.
It will work whichever way you’re told it will work. Find two people who have never heard of pendulum work before - tell one that a circle means girl and the other a circle means boy (out of each other’s hearing, of course). Their pendulums will swing accordingly, only they’ll swear up and down they’re not moving it on purpose. And they’re not, sincerely - it’s just very fine motor twitches that are so small they’re not even felt by the person themselves.
I’ve learned how to hold my hand still and change from circle to line, or horizontal line to vertical line, and I’m really, honestly not “moving” my hand at all, at a level perceptible even to me. But of course I am, I just can’t feel it.
This kind of unconscious muscle movement is leading to some really great prosthetic work - attach the right kind of sensor, and a person only has to *think *their metal hand closed, not consciously put pressure on buttons or levers. It’s really cool.
I don’t know about old wives’ tales, but there’s some new “scientific” stuff out there that has my eyebrows arched. My daughter-in-law is pregnant, and she’s been instructed to eat lots of vegetables because the baby can now taste what she eats, and her eating lots of vegetables will cause the baby to be more receptive to vegetables when it is born. It just sounds like peasant superstition to me.
Heh heh. My poor husband has been doing most of the dishes lately, but at least I’m honest about it - I just can’t reach the sink anymore.
Actually, here’s a myth that isn’t so old that I’ve stumbled across recently. My MIL wanted to know if I was dilated at all. I had to break the news that the last pelvic exam I had was about seven months ago, and even if they did one today, it wouldn’t tell us if the baby’s coming tomorrow or three weeks from now. I’m guessing when she was pregnant, they checked frequently and thought dilation meant imminent birth, but the statistics don’t bear (ha) that out at all.
Must be a very young old wife, given that antibodies are pretty much yesterday’s discovery…
A friend of mine, Swedish, went to Portugal on her honeymoon, all three of them. No, not all three honeymoons: all three people, husband, bride and upcoming baby. She remembers it as “horrible” because they’d go to expensive restaurants, ask for the best steak (she doesn’t like fish) and the waiters were biologically unable to bring it “burned through”. She says “didn’t he see I was pregnant?” My reaction when she fist said this was “uh?,” I had no idea what she was talking about and I sympathize with the waiters, you just don’t burn a one-inch-thick prime cut. But apparently this is one of those things that doctors all over the place are telling women to do, which women in Spain (1) had been resisting but apparently now if a pregnant woman so much as sniffs a die of jamón serrano she risks being assaulted by any female in view…
1: where cured-but-not-cooked meats are a long-standing tradition and the kind of illnesses transmitted by uncooked meats are about as common as dogs with six legs; veterinary controls here are a lot more strict than in the USA, mentioned not as USA-bashing but just as a first-world reference, ok?
Here’s one I made up myself:
The mom shouldn’t clean the litter box during any of the time when one is thinking it might be nice to have a baby, during the time trying to conceive, during the pregnancy or at least nine years after the baby is born.
And that just makes it more cool than what I had learned from magic books. 
Okay, you’re just about the cutest pregnant lady I’ve ever seen!
Not pregnancy, but for newborns - my paternal grandmother (born and raised in Poland) told my mother when I was born that she shouldn’t hold me up to look in a mirror, or it would give me crossed eyes. She also told Mom not to cut my fingernails, or it would make me steal. I guess she was supposed to gnaw the nails off??
This one isn’t a myth. Toxoplasmosis is protozoal parasite that can cause serious mental deformities babies if the mother is exposed to it for the first time of her life during the first trimester. This is the disease that most people kill their cats over when they get pregnant. And while exposure to day old cat poop can cause infection in humans, it is much more common for pregnant women to be exposed from under-cooked beef. The parasite lives in the muscle tissues.
However, if your friend was visibly pregnant, then she was beyond the point where toxoplasmosis is a threat to her baby. Moreover, prevalence of the disease in the beef population is not huge (Side note: if you can provide me with resources on how European beef has less food borne illness than US, I’ll buy you a drink ) Still, getting food that is cooked thoroughly is a good idea for anyone.
Also, if anyone is wondering, provided someone other than the pregnant lady cleans the litter box, and that the box is cleaned at least once a day, the odds of catching toxoplasma infection from your cat are basically zero. Most cats are not infected anyway.
Would you hush? I think you’re trying to ruin it for us moms. See above - no mom should clean out the litter box!