Fewer women give birth on Halloween than on Valentine's Day, finds a new study. But this may not be a mere calendar coincidence. Researchers at the Yale School of Public Health suggest that pregnant women appear to be swayed by the cultural symbolism of the two holidays -- skeletons versus cherubs --  and this might influence their baby's arrival date.

They speculate that mothers-to-be may avoid delivering on the October holiday associated with death and witches. But scientists suspect that women have a more favorable view of Valentine's day, which is linked with love and romance, and may try for a Feb. 14 delivery.

Researchers raise the possibility that pregnant women may have some control over the timing of childbirth. Their findings suggest that a spontaneous birth (giving birth naturally) may be less spontaneous than doctors previously thought.

"The positive connotations of Valentine's Day may increase a pregnant woman's will to initiate birth and the negative connotations of Halloween may precipitate her will to resist giving birth," write the researchers. In other words, maybe a woman's mind is consciously or unconsciously influencing her hormonal mechanisms, and telling her body to speed up or slow down her baby's birth.

In the study, published in the journal Social Science & Medicine, researchers reviewed more than three million U.S. birth records. They looked at the number of babies born in the two-week period surrounding Halloween and Valentine's Day between 1996 and 2006, and considered the mother's delivery method.

Researchers selected cultural holidays with widespread participation, like Halloween and Valentine's Day, because unlike religious or national holidays, these would not affect hospital staffing rates. They found that births -- both scheduled and unscheduled -- increased on the holiday associated with hearts and flowers but dropped on trick-or-treat.

On Valentine's Day, they observed a 3.4 percent increase in induced births, a 3.6 percent lift in spontaneous births, and a 12.1 rise in cesarean deliveries compared to the seven days before and after the heart-themed holiday. 

And there was a noticeable decline on Halloween. There was an 18.7 percent drop in induced births, a 16.9 percent dip in cesarean deliveries, and a 5.3 percent fall in spontaneous births compared to the other days in this two-week timeframe.

During this 11-year period, a woman's odds of giving birth on Valentine's Day went up by 5 percent overall, but it went down by 11.3 percent on Halloween. Although researchers admit they don't know the exact mechanisms behind this birth-timing pattern, they suspect that psychological factors and cultural beliefs can impact when women go into labor.

Of course, birth records don't reveal what may have been going on in couples' minds or lives nine months earlier.

Halloween and Valentine's babies, let's hear from you. Is it fun to share your birthday with pumpkins and costumes or hearts and romance? Others who have holiday birthdays feel free to add your comments.

Related:

• Three days after birth, newborn has teeth. What?!
• 'Baby fever' is a real thing -- and not just in women
• Cravings for baby powder, and more tales of pica

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Everyone knows not to get between a bear and her cubs, but if mama bears used bottles maybe they’d be a little more mellow.

A study published in the September issue of Psychological Science found that nursing mothers are roughly twice as aggressive as bottle-feeding moms and women without children when confronted by a threat.

“Maternal defense does not involve nursing mothers going out and looking for bar fights, but when they have a helpless baby, they’re more likely to defend themselves when the fight comes to them,” said Jennifer Hahn-Holbrook, a postdoctoral fellow at UCLA’s Department of Health Psychology.

Similar aggression has been observed in lactating monkeys, rats, mice, deer, hamsters, lions, prairie voles and sheep. When reading a book about how vicious predators become loveable moms, Hahn-Holbrook noticed that many of our preconceptions about mothers being quite docile were actually wrong for other species. She wondered if the same thing would hold true for humans.

She and other researchers recruited 18 nursing mothers, 17 women who were feeding formula to their babies and 20 non-mothers. The women were told they’d be playing a competitive computer game against a research assistant posing as a rude and aggressive study participant. When the women “won” a round of the game, each got to choose how long and loudly they would blast their opponent with an annoying sound.

After accounting for other differences, the researchers found that breast-feeding mothers delivered sound blasts to the rude opponent that were more than twice as loud and long as those administered by non-mothers and nearly twice as loud and long as those by bottle-feeding mothers.

The study suggests that lactation—and not just motherhood in general—kicks maternal protection into overdrive. During the confrontations, for instance, nursing moms exhibited lower blood pressure levels than the other two groups of women. That can actually dampen fear and stress responses and give them a little extra moxie to defend their offspring, the study concluded.

“We interpreted this as breastfeeding being nature’s way of helping moms calmly but effectively deal with potential threats,” Hahn-Holbrook said. But in a day and age when we’re not exactly likely to be chased by saber-toothed tigers, does the aggression factor add any benefit?

“That’s completely beyond the scope of our study, but I’m sure there are plenty of contexts in which moms could use a little extra help in that regard,” she said. “This wouldn’t just come up in terms of predators but might also encourage a mom to run back into a burning building and save an infant. I definitely think that moms generally are inspired to do that, but I wonder if lactation would just give moms a little extra push and a little extra courage.”

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Sorry to break it to you parents: But your cute-as-button baby is unlikely to appear in People magazine's Most Beautiful People or Sexiest Man Alive issues more than 18 years from now. 

When researchers put the idea behind the hit song "You Must Have Been a Beautiful Baby" to the test, it didn't hold up. Being a beautiful baby did not predict who would become the best-looking adults, a new study found.  

Facial attractiveness is not stable from infancy into adulthood, suggests research published in the journal Infant Behavior & Development. 

In one study, 253 college students rated the attractiveness of 40 infants (under age 2) and young adults (age 16 to 18) on a scale from 1 for "not that cute or attractive" to 7 for "very cute or attractive." Students evaluated each person's baby and high school yearbook photos. 

All the pictures were grayed head shots showing the face from ear to ear and hairline to chin. That way coloring preferences, bad hair or ugly clothes wouldn't sway the judges. 

In general, students rated more tykes as better looking than high school seniors. But the results showed there was no relationship between cuteness as a little one and attractiveness as a grown-up. A second study with 72 participants evaluating a different set of infant and adult photographs had similar findings. 

"At first we thought the old adage that an attractive adult 'must have been a beautiful baby' must be true due to the constancy of one's genetics," says Marissa Harrison, an assistant professor of psychology at Penn State Harrisburg in Middletown, Penn. But then we realized babies have likely evolved to be cute to elicit care from parents, she explains.  This improves their odds for survival and reproducing as adults. "Simply put, cute babies grew up and left more descendants than not cute babies," adds Harrison. 

Adorable babies might not turn into real lookers as men and women because hormones affect facial appearance. "The proportion of androgens and estrogens in our bodies as we grow can determine our brow and jaw structure, skin clarity, and facial hair," says Harrison, the study's lead author.  

So is there a better age during childhood that would give a better indication of adult attractiveness? According to Harrison, the hormones affecting facial structure and appearance kick in around puberty, so you'd probably have to wait until then to make a prediction. 

To be more scientifically correct, perhaps the lyrics need to be "You Must Have Been a Beautiful Teenager"? 

As parents and grandparents cradle their amazing bundles of joy wondering what the future holds, keep yet another popular saying in mind, beauty is in the eye of the beholder. 

What have you noticed, readers? Do irresistible infants become knockouts when they get older?

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James Cheng / msnbc.com

And I was like, baby, baby, baby, ohhh!

They squeal, they scream, they burble and burp -- and according to popular culture (not to mention various episodes of "30 Rock" and "Sex and the City"), nearly every American female over the age of 30 is ga-ga to get their hands on one of them.

Now a new study in the psychological journal Emotion claims that "baby fever" -- that sudden, visceral, and almost irresistible urge to have a baby -- not only exists, it can be found in both men and women.

"Women reported that it happened more frequently and more strongly but it's there for both men and women," says Gary Brase, associate professor of psychology at Kansas State University who along with his wife Sandra Brase, spent nearly 10 years studying the phenomenon.

The researchers, who have two children, first looked at three theoretical viewpoints as to why baby fever might exist and where it could come from. One theory had to do with gender roles, i.e., women think they should have kids because that's what they're taught women are supposed to do. A second theory had to do with nurturing.

"Humans are biological organisms, we have a sex drive and we nurture once a child is born," says Brase. "We looked at whether baby fever was due to people looking at someone else's child and then having that trigger misplaced nurturance. But it wasn't that either."

A third theory had to do with timing -- the brain delivering a signal that this could be a good time to have a child. But when they talked to their test subjects (a total of 337 undergrad students and 853 general population participants gathered via the Web), none of these theories seemed to hold up.

Instead, three factors consistently predicted how much a person wanted to have a baby.

"The first two had to do with the visual sensory things," says Brase. "Seeing a baby, hearing a baby, smelling a baby led some people to want to have a baby."

Conversely, hearing a baby screaming, smelling a dirty diaper or being exposed to spit-up or other "disgusting" aspects of babies, led other people to not want a baby or come down with what you might call "anti-baby fever."

A third factor had to do with trade-offs that come with having children.

"People would say, 'I don't want to have a baby because I don't have money or I don't have time or I don't have a partner,'" he says. "All of the rational thoughts. That showed up as a third factor."

Rachel Kramer Bussel, a 35-year-old writer and editor from Brooklyn, has no doubt baby fever exists. In fact, she knows exactly when she caught it.

"I've wanted to have a baby for about five years, since I turned 30," she says. "I have to force myself to not stare at strangers' children when I'm out. It feels like both this physical tug and an emotional one. There's something about holding a baby close to me that makes me feel like everything is right with the world."

Russell Williams, a 39-year-old software engineer, says he, too, has been bitten by the baby bug.

"I don't get a yearning -- it's not a physical feeling -- but I love being around kids and get my baby fix by babysitting friends' kids," he says.

Williams says his baby jones has even led him to throw a birthday party for the 2-year-old daughter of a female friend, complete with decorations, activities and a Dora the Explorer cake, which he baked himself.

"I always assumed I'd have a family with a kid or two and a wife by now," says the Seattle bachelor. "I enjoy being around kids; it's fun to interact with them. Although it doesn't make my stomach do flip-flops. So maybe my baby fever is more of a cold."

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The littlest art critics -- a bunch of 9-month-olds in Switzerland -- preferred the works of Picasso over Monet in a recent study. 

Paintings by the Spanish artist appealed more to the diaper-clad set than those by the Frenchman in a series of five different experiments published in the journal Psychology of Aesthetics, Creativity, and the Arts.

Now, you may wonder: How much insight can an infant offer when comparing cubism to impressionism?

"At 9-months of age, infants' vision is already much the same as in adults," says Trix Cacchione, a psychologist at the University of Zurich, and the study's lead author. "To an infant, a painting is most likely only a perceptual pattern and their aesthetic preferences are most likely guided by low-level functions of the visual system."

Tim Hales / AP

Everyone is a critic. Even babies have an opinion when it comes to art, prefering Picasso to Monet.

Researchers wanted to understand whether the little ones would favor one artist's style over another, what types of visual images appealed to them (Picasso's highly-abstract elements vs. Monet's more realistic landscapes), and whether babies display a preference for certain colors, shapes and contrasts.

Not yet art snobs -- well, barely able to offer more than some high-pitched squeals, smiles and drool -- the babies were shown the artwork on a computer screen while sitting on a parent's lap.

In one of the experiments, 24 infants (14 girls, 10 boys), were shown either six paintings by Picasso or the same number by Monet, and researchers measured their "look time" at each image. They then introduced two paintings side by side, one from each artist, Picasso's "Landscape of Juan-les-pin" and Monet's "Poppy Field Near Giverny."

Babies who had been viewing the Monets preferred the Picasso -- it was something new and different to their eyes. But the infants who had been shown the Picassos also looked longer at the new Picasso.

Some tykes were booted from the study because of "fussiness." Being a research participant is tough stuff when you're not yet 300 days old and your diaper may be filled with a stinky mess.

In another trial, 19 babies were shown the same Monet and Picasso paintings they had seen before in color, but this time they saw them in black-and-white (thanks to the wonders of Photoshop). Once again, the little ones still went for Picasso over Monet.

Cacchione says she's previously observed that infants are fascinated by abstract paintings, like Picasso's. "What surprised me was that the preference was not connected to colors."

The Picasso paintings featured bold, vivid colors and sharp contrasts while Monet's had softer hues and subtler contrasts.

Although Cacchione admits she can only speculate on why infants were partial to Picasso, her hunch is "they were easier to process and afforded the most stimulation to their still developing visual system."

When asked how parents could put some of these findings to practical use, she suggested, "Maybe we should decorate young infant's toys with patterns including bright contrasts and not with less contrastive calming colors."

Perhaps that may inspire a new generation of artists.

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