Babies can’t taste salt, don’t shed actual tears, and are missing kneecaps! Here, more weird facts about our littlest humans.
They Can’t Taste Salt
Young babies are born with a well-developed sense of taste, but not for salt. Studies show that babies can’t taste salt until they’re about four months old. They can taste other flavors as well as adults can, especially sweet, bitter, and sour flavors (which might explain all the “baby tastes lemon” videos on YouTube), and maybe even better: some studies indicate that babies actually have more taste buds than adults do.
They Cry … But Don’t Shed Tears
Newborns cry an awful lot, but they can’t shed tears: they don’t have functional tear ducts until they’re between three and twelve weeks old. (They can, however, produce “basal tears,” the nonemotional tears we produce constantly to keep our eyes moist.)
They Have No Kneecaps
Really! Well… sort of. If you X-ray a baby’s legs, you likely won’t see anything where the kneecaps should be, or if you do, it’ll just be small, smudgy spots. Reason: all bones start off as cartilage, and they harden, or ossify, over time. Kneecaps take an especially long time to form (from three to five years) and because cartilage doesn’t show up on X-rays, babies appear to have no kneecaps. That lack of hard kneecaps is a good thing, because the spongy tissue serves to absorb some of the abuse toddlers take during their crawling months and from their frequent falls.
They Have More Bones Than Adults Do
Way more: about 300, compared to our paltry 206. The reason is related to why they lack real kneecaps: some of a baby’s separate bones fuse together into single bones as they ossify in the months and years after birth. Example: the skull starts off as several separate bones that fuse together into one large bone by about the age of two.
While still in the womb, babies are exposed to high levels of the female hormone estrogen. At birth, when the baby becomes “disconnected” from mom, as it were, those estrogen levels fall rapidly and in girls can cause what is known as pseudomenstruation, similar to menstruation in young and adult women. (Sharp drops in estrogen and related hormones are in fact what triggers menstruation in adult women.) Mothers unaware of this phenomenon often freak out when they see a little blood in their babies’ diapers, but it’s very common and happens in about a quarter of all female babies, usually in the first seven days of life.
The drop in hormone levels that causes psueudomenstruation can also cause galactorrhea, a phenomenon in which newborns develop tiny breast buds, and actually lactate, producing tiny amounts of milk from their nipples. It can happen in boys as well as girls. Like pseudomenstruation, it’s not dangerous or uncommon, occurring in about 5 percent of all newborns, and can persist for up to two months. (In old European folklore, milk from the breasts of newborn babies was referred to as “witch’s milk” and was thought to have magical powers.)
They’ve Drunk Their Own Pee
Babies start urinating in the womb just a few months after conception. Where does it go? They drink it! More precisely, the urine mixes with the amniotic fluid surrounding the baby in the uterus. And by the third trimester of pregnancy, a fetus swallows about a liter of amniotic fluid every day. Since a fetus does not need hydration or nutrition in the womb (that comes from mom via the umbilical cord) experts say this serves mostly as practice for swallowing and digestion. This means that every last one of us spent several months of our lives drinking our own pee. (Fetal pooping is rare.. .but it does happen sometimes. And that’s all we’re going to say about that.)
They Can Remember What They Tasted in Utero
As we told you earlier, newborn babies cannot taste salt, but they can taste other flavors, and they can taste those flavors while they’re still in the womb, starting from about four or five months into pregnancy. Amniotic fluid is believed to be affected by the food the expectant mother eats, which, in turn, is believed to affect a baby’s flavor preferences after birth. If a pregnant mom eats a lot of garlicky foods, for example, the baby will taste that in her amniotic fluid in the womb, and will have a good chance of being drawn to garlic-flavored foods after birth.
Sometimes babies are born with just a few tufts of hair on the top of their heads, or a fine “peach fuzz” all over their tiny domes. This isn’t what we’re talking about. As it develops in the womb, a baby’s entire body becomes covered in a thin layer of hair called lanugo. Child development experts say that the hair helps regulate a body temperature in utero. So, if your baby is born looking like a werewolf-in-training, don’t worry: it’s perfectly normal. The hair will gently fall out on its own over the first few weeks of the newborn’s life. If your baby wasn’t born covered in lanugo, well, it already fell off toward the end of gestation, and the baby ate it.