Category: parenting

Do Fish and Coconuts Reverse Prenatal Stress?

Posted in news, parenting, pregnancy, psychology, science by jenapincott on July 22, 2011

Is it any coincidence that the most laidback people I’ve ever met hail from Brazil, land of fish and coconuts?  

The mellowness of Brazilians came to mind when I read a study on prenatal stress to be published next month in the International Journal of Neurodevelopmental Medicine. The researchers, including lead author Carlos Galduróz, are biologists at  Universidade Federal de São Paulo (in Brazil).

It’s been long known that significant prenatal stress — characterized by a blitz of  the stress hormone cortisol — harms a fetus. Prenatal stress results in an increased risk of premature birth and low birthweight.  In humans, it’s linked with anxiety, attention deficit disorder, impaired memory, low test scores in childhood, and depressive behavior in adulthood.  Rats whose mothers are exposed to extreme stressors are likelier to have impaired motor skills and are slower to learn.

Intriguingly, there’s evidence that the mother’s diet might offset some of these disadvantages.  A baby whose stressed-out mom ate “special” foods during pregnancy and lactation may fare better than one whose equally stressed -out mom ate a normal diet. 

Galduróz and his colleagues were curious to know if the composition of fat in a prenatal diet might make the difference. So, during the equivalent of second and third trimester, they subjected some of the rats in their study to extreme stress — restraint and bright lights for forty-finve minutes, three times daily.  Some of these pregnant rats were fed a diet high in omega-3 fatty acids, the kind found in salmon, sardines, and other fish. Others were fed a diet high in saturated fatty acid from coconut milk. A third group ate normal rat chow.

The results?

As expected, babies of stressed-out moms had lower birth weights.  The surprise came three weeks later:  Babies whose moms ate fish oil or coconut fat diets during pregnancy and lactation gained weight quickly. So quickly, in fact, that they became the same weight as the babies whose moms weren’t stressed during pregnancy.  In other words, fish and coconut fats reversed the impact of low birthweight, a potentially dangerous effect of prental stress.

That’s not all.

Babies exposed to prenatal stress were more active (restless) than other pups if their moms were on a regular or coconut-oil diet.  Interestingly, if a stressed-out mother was on a fish oil diet, her pups were not more restless than those of pups with non-stressed moms.

In an earlier study by the same authors, adult rats whose moms ate a coconut fat or fish oil-based diet released fewer stress hormones (a reduced corticosteroid response) than rats whose moms ate a normal diet.

Many studies have shown that fish oil, omega-3s, modulate mood by reducing the stress response. This has been shown in rat studies, and also in many (but not all) human studies.  Is it possible that when a mother consumes food containing omega-3s, her babies are less agitated? Are they happier?  Of course, rodents express anxiety, neuroticism, and depression differently from human babies.  But the healing effect of nutrients is fascinating.  Do stressed-out moms on fish-and-coconut diets have happier, healthier babies than their equally stressed peers who don’t eat as well?

For the real possibility that  fish and coconut oil have prenatal physical and psychological perks, I link to a favorite recipe here. It’s for moqueca, a stew made of fish and coconut fats, from Bahia, the Coconut Coast of Brazil.

 *If you like this blog, click here for previous posts and here to read a description of my most recent book, Do Gentlemen Really Prefer Blondes?, on the science behind love, sex, and attraction. If you wish, check out my forthcoming book, Do Chocolate Lovers Have Sweeter Babies?: The Surprising Science of Pregnancy. 

 

 

Do Flame Retardants Make Us Dimmer?

Posted in parenting, pregnancy, psychology, science by jenapincott on July 6, 2011

When I was in the second trimester of pregnancy, my husband and I bought a new king-sized mattress.  Like all cotton mattresses sold in the U.S., ours had been treated with a flame retardant containing polybrominated diphenyl ethers (PBDEs) and/or organohalogen compounds (OHCs). Flame retardants are also in pillows, car and airplane seats, drapes, rugs, and insulation. They’re in electronic equipment, like TVs, and in the dust on top of TVs.  They’re in air and soil and breast milk.  Almost all humans have flame retardants flowing through their veins.

             Around the same time I got my new mattress (on which I tossed and turned in third trimester), two surprising studies were published on the effects of flame retardants on fetuses and young children.

Study #1

A group of researchers at the University of Gronigden in the Netherlands recruited nearly 70 pregnant women in third trimester, taking samples of their blood and measuring it for PBDEs and OHCs. Five years later, the children were given standardized developmental tests for motor skills (balance and coordination), cognition (intelligence, spatial skills, control, verbal memory, and attention), and behavior.

The result:  PBDEs were correlated with worse performance on fine motor tasks and a shortened attention span.  Strikingly, they were also linked with better coordination and visual perception, as well as better (more placid?) behavior.  OHCs, meanwhile, were correlated with worse fine motor skills. Oddly, these kids had better visual perception.

 Study #2

 Researchers at Columbia University tested for PBDEs in the cord blood of nearly 400 women who delivered their babies at a New York City hospital.  These children were given mental and motor development tests in infancy and, later, at four-to-six years. These tests measure memory, problem solving, habituation, language, mathematical concept formation, and object constancy.  They also assess ability to manipulate hands and fingers and control and coordinate their movements.

 The result:  At both age intervals, children who had higher cord blood concentrations of PBDEs scored significantly lower on tests of mental (lower IQ) and motor development.  This was particularly evident at age two for motor skills and age four for IQ (nearly 8 points lower for certain PBDEs).

 

            Are flame retardants slowing us down? Correlation is not causation, but there’s a real risk that they do — and researchers have some ideas about how these chemicals have a toxic effects on the brain. OHCs (for instance) have been found to decrease a fetus’s production of thyroid hormone by interfering with thyroid receptors. This leads to an increase in thyroid stimulating hormone (TSH). Brain development in the fetus relies on the precise timing and quantity of thyroid hormone; too much or too little causes developmental delays. High prenatal exposure to TSH is associated with lower IQs – 4 points less on average.  During critical developmental periods, PBDEs and OHCs may also have a toxic effect on neurons in the hippocampus, the memory region of the brain, by reducing the number of neurotrasnmitter receptors.

            Infants and toddlers have what researchers call a high “body burden” of flame retardants. Household dust, which floor-playing infants and toddlers encounter constantly, accounts for 80-93 percent of postnatal PBDE exposure, followed by breast milk (however, the benefits of nursing appear to outweigh this drawback; breastfed babies score higher on neurodevelopmental tests). 

            A disturbing fact is that American kids have levels of PCBEs that are 10 to 1,000 times higher than their peers in Europe or Asia. We produce 1.2 billion pounds of the stuff annually. (Interestingly, the Scandivanian study, whose subjects had lower levels of prenatal exposure, found no IQ deficit while the U.S. study did.) Consider our nation’s problems:  attention deficit disorder, placidity, lower standardized test scores in reading and math.

Are flame retardants making kids dimmer?

            The question fires up the imagination.  Should pregnant women be advised to avoid, say, dusting and buying new mattresses in the same way we avoid emptying the litter box (to avoid toxoplasmosis)? Are the perceived gains in visual perception real, and, if so, why, and do they come at the expense of other abilities? Are urban kids at a higher risk  than average? Are there naturally flame-retardant materials that we can use in lieu of chemicals?   More research, especially on American kids, is warranted.

            After all, the nightmare scenarios can keep an expectant mom up all night, tossing and turning on her nonflammable mattress.

 

 * If you wish, check out my forthcoming book, Do Chocolate Lovers Have Sweeter Babies: The Surprising Science of Pregnancy. 

 

Are Extroverts That Way Because of Their Fathers?

Posted in parenting, psychology, science by jenapincott on June 24, 2011

All babies demand their parents’ attention. But how many 11-month-olds demand the attention of strangers, too? Ours does. We bring her to restaurants and she scans the room until she catches someone’s eye. My husband will pick her up and carry her over to her admirer, whom he’ll chat up. Dad’s a socialite, Baby’s a socialite. Mom reaches into her bag and pulls out a book.

You might think your baby’s social confidence depends on the usual mix of genes and environment. This is true, but it might not be the whole truth. There’s also evidence that children rely more on their father’s social signals than their mother’s. That is, socially confident dads may have more socially confident kids. Socially anxious fathers may have more socially anxious kids. It matters less whether Mom is a social butterfly or a bookworm.

The bulk of the research on paternal influence on sociability comes from Susan Bogels, a professor in Developmental Psychopathology at the University of Amsterdam, and her colleague Enrico Perotti. In a recent review, Bogels and Perotti draw on research that suggests a dominant paternal role in their children’s sociability, including:

In one study, 9-11-year-olds were asked to imagine themselves in a series of stories involving strangers, while their mother and father responded in a socially anxious or socially confident way. Children who had socially anxiety were more influenced by their father’s reaction more than their mother’s.

A study of boys with behavioral problems, including social anxiety, found that fathering, but not mothering, predicted the children’s level of inhibition. In another study, secure infant-father attachment, but not infant-mother attachment, predicted stranger sociability among toddlers.

• Among kids enrolled in treatment for social anxiety, those whose fathers had high levels of social anxiety had a worse outcome (were more socially anxious) than those whose mothers had it. Socially anxious mothers are not as likely as socially anxious fathers to make their kids less sociable.

So here’s the mystery: Why would fathers, who have less to do with childrearing than mothers, have more influence on their children’s sociabilty?

It’s an interesting question, and Bogels and Perotti have an interesting answer. “In the course of human history,” they write, “fathers specialized in external protection (e.g. confronting the external world outside the clan or extended family), while mothers provided internal protection (e.g. providing comfort and food). Therefore, children may be hardwired to respond more to their father’s signals about the social world than the mother’s, and adjust their behavior accordingly.

Through the ages, it benefited children to rely more on their father’s than mother’s cues about whether unfamiliar people are generally hostile or cooperative. Of course, gender roles have long since changed – moms go out into the world every day and meet strangers – but our instincts haven’t.

So the lesson here is that fathers orient their children outward, mothers inward. When researchers observed a group of toddlers taking swimming lessons, they took note of where the parents stood. Mothers protectively stood in front of their babies, encouraging face-to-face interaction with them. Fathers stood in back, so that their children would face their social environment.

∞∞∞∞∞∞∞∞∞∞∞∞

Bogel and Perotti’s review includes a fascinating aside about paternal roughhousing and its effect on children’s social confidence. Rough-and-tumble play – I think of my husband tossing our infant in the air, spinning her around, throwing her over his shoulder, as she giggles and squeals- gets a scientific seal of approval.

Here’s why. Kids learn to associate physiological arousal – a racing heart, tight chest, spinning head – with fun instead of fear, which crosses over into other social interaction. Roughhousing also involves behavior – being aggressive, sneaky, teasing, playful – that requires different roles and different responses, and forms a basis for social skills. By pinning kids to the ground, swinging them like sacks of potatoes, attacking them and getting attacked – fathers make their progeny more confident.

∞∞∞∞∞∞∞∞∞∞

So many questions. If we have evolved so that fathers strongly influence their children’s sociability, what does this mean?

It means that fathers who are socially anxious themselves are likelier to have kids who are not socially confident. If a kid suffers from severe social anxiety, perhaps his or her father should be involved in the kid’s therapy or get therapy himself. But what about kids who don’t have fathers who are involved or live at home? How do mothers compensate? And what about gender? So far there is no evidence that boys are more susceptible to the father’s signals than are girls, but is this really so? And what about other male figures – male teachers, older brothers, uncles, grandfathers – are they equally influential? At what age is paternal influence on sociability strongest? And are paternal genes more influential here too?

Further research is warranted. Until then, we can wonder about the great socialites in history – the Jackie Os, Andy Warhols, Paris Hiltons, Truman Capotes, Gloria Vanderbilts, Nan Kempners, and Ivana Trumps. Did they get it from their dads?

 

 

 

Are Men Likelier to Cheat When Their Partners are Pregnant?

Posted in parenting, pregnancy, psychology, science, sex by jenapincott on June 13, 2011

It’s bad enough that  Congressman Anthony Weiner had been taking photos of his naked self and sending them to women who weren’t his wife.  It’s worse when we learn that his wife is three months pregnant.

Aha, that it!, some cynics claim.  Now that Weiner’s oats are sowed, he’s exploring new (and, if the twittering teen rumor is real, very green) pastures.  It’s only natural.

But is it?  Are men really more likely to cheat when their wives are pregnant?

Turns out, the answer is that it depends on the man.

Reviewing the studies of pregnancy and sex, it seems there are three categories of expectant fathers. 

  • Type Z cheats or wants to cheat (the Weiners). 
  • Type Y desires his pregnant wife more than ever.
  • And then there’s Type X  — a man who has a decreased sex drive and a lower risk of cheating on his wife.

The bad news is that at least one study found that, yes, the risk of a given man to cheat on his wife increases during pregnancy, even if he is otherwise satisfied in his marriage.  His reasons? He may feel ambivalent about the pregnancy or the changes that go with it. His partner, especially in her first and third trimesters, may not feel like having sex.  Her sex drive may diminish. She may think her body is unattractive.

(Incidentally, bodily dissatisfaction happens to be the number one reason why most women have less sex during pregnancy.  Most of us think pregnancy is a turn-off for men.  That’s a misconception.)

But here’s the good news for pregnant women.  Fact is, many men — the majority as found in this study — desire their pregnant partner even more over the course of the pregnancy, even if they aren’t having as much sex as before. They find her as physically attractive as she was prepregnancy, if not more so. These are usually the Type Y guys. Another study found that, while couples had sex less frequently in third trimester, the only circumstances under which men change their sexual behavior is if they are older or worried about the safety of the fetus. (Note:  Sex does not raise the risk of miscarriage in pregnancies that are not high risk.) Otherwise, men desire sex with their wives just as much.

From an evolutionary perspective,this makes some sense.  Women benefited from having their mates around to help support them through pregnancy and childrearing. Sex helps men stick around.

The Type X expectant father – the one with a low sex drive and a lower risk of infidelity – may overlap with Type Ys. These are men who, at some point over the nine months, are afflicted with pregnancy symptoms:  nausea, weight gain, mood swings, fatigue, even vomiting. Hormones are the culprit.  These men have higher levels of prolactin, a hormone associated with sluggishness, weight gain, and bonding and parental behaviors.  Their testosterone levels plummet, making them less combative and sexually aggressive.

There’s an upside to Type Xs. It turns out that these faithful, fattening men display the most fatherly behavior when the baby arrives.  As new dads, they’re more likely to hear and respond to their infant’s cries.  They’re more compassionate and tolerant.  They make better fathers.

One might speculate that Weiner’s Type-Z behavior while his wife is pregnant doesn’t bode well for Weiner’s fathering instincts. It’s clear that if any hormone is raging in the man, it’s testosterone — not prolactin. He is probably not sharing his wife’s morning sickness and taking turns with her over the toilet.

There’s no crime in what Weiner has done; he’s just another politician more interested in power more than paternity.  But he is making us a little nauseous.

 *If you like this blog, click here for previous posts and here to read a description of my most recent book, Do Gentlemen Really Prefer Blondes?, on the science behind love, sex, and attraction. If you wish, check out my forthcoming book, Do Chocolate Lovers Have Sweeter Babies: Exploring the Surprising Science of Pregnancy. 

 

Where Do Demanding, Unweanable Babies Come From?

Posted in news, parenting, pregnancy, psychology, science by jenapincott on May 24, 2011

A season ago, when my daughter reached the six-month mark, her pediatrician told us to introduce her to a new food every few days and see what she likes. It wasn’t time to wean her, but soon it will be, and supplementation should help the transition. So I lovingly shopped for organic fruits and vegetables: apples, bananas, avocados, peas, and so on. I presented them passively — as items for her to experiment withon her placemat — and actively, by making mmmms, playing airplane, and swallowing the goop and showing her my tongue.

Three months later, we’ve made astonishingly little progress on the solids front. At best, the infant deigns to nibble delicately on peas and lentils. She’ll squish the bits of mango and avocado on her plate and drop them on the floor. She’ll taste a food then whip her head to the other side and bat away the spoon. She wrinkles her nose.

All she really wants to do is nurse. Baby loves to nurse. She cries and cries in the wee hours of the morning because she wants to nurse. She is tall and heavy for her age.

Who’s to blame (at least in part) for her unweanable stubbornness?

Her dad. 

It’s not only convenient to blame the father for babies who won’t give up nursing, It’s scientific.  There’s evidence.    

Here’s how it works, according to a new study Bernard Crespi, an evolutionary biologist at Simon Fraser University.  How much and how long a baby nurses depends in part on her genes. The genes she inherits from her father have an ulterior motive.  Paternal genes want the baby to extract as much as possible from the mother.

Paternal genes are thought to influence:

  • suckling strength  (so the baby extracts as much milk as she can)
  • tongue size (a larger tongue is a better suction pump)
  • crying  (for maternal attention and food)
  • appetite and speed of eating
  • duration of breastfeeding before weaning
  • night-time suckling (results in suppression of periods, which helps delay future pregnancies/siblings)

The genes that influence these behaviors are active only when they come from the dad. This is called genetic imprinting — when only the genes from one parent are expressed. Dad’s genes strongly affect the intensity of infant behavior.  Only a tiny percentage of human genes are imprinted. 

Dad’s genes are greedy for a good reason. From a biological perspective he has nothing to lose by making sure this particular offspring who carries his genes demands a lot of her mom — including suckling often, crying a lot, and taking a long time to wean. This behavior may be essential to a child’s survival in a setting in which resources are limited. “Weaning” genes have been shaped this way under evolutionary pressure in a premonogamous era.

Mom’s genes, meanwhile, are more moderate.  They want the child to survive but dial back the feed controls. They’d prefer for a baby to self-feed and start solids sooner. Mom’s genes push moderation to save resources (time and energy) for her other (or future) offspring. When paternal genes are disabled and maternal genes are active, babies have Prader-Willi syndrome, a condition that manifests as inability to latch and suckle effectively, complacency, and lack of crying or other solicitation for food.  These infants wean early because they never really nurse. They fail to thrive.

Demanding, unweanable infants come from dads. At a minimum, paternal genes play a real role in their aggressive eating, crying, and nursing behaviors.  

Now that they’re outed, perhaps guilty fathers should be the ones to work the night shift and scrape  food off the floor?

Do Brothers Stall Their Sisters’ Sex Lives?

Posted in parenting, psychology, science by jenapincott on March 20, 2011

Nearly eight months ago I gave birth to a baby girl. The child is now a seam-popping twenty-plus pounds. Infants, they grow so quickly it’s creepy — my thoughts fast-forward through her teething years to the teens, and I’m terrified. Problem is, my family lives in New York City where children want to be adults. The weenies of tweens should stay in their jeans, but all too often they don’t.

The onset of girls’ sexual maturity depends a lot on the social environment — peers, culture, and so on. A recent study by Australian behavioral ecologists Fritha Milne and Debra Judge found that it especially depends on the family environment, and not in the expected ways of curfews and chastity pledges. Sure, if you’re a teenage girl your parents might hold you back from trying to lose your virginity. So may your grandparents and any other authority figure in your family.

But so might your little brother.

Milne and Judge recruited nearly two hundred women and seventy-six men, all living in or around the city of Perth, Australia, and asked them questions about their family lives and sexual development. The results were that girls with only younger brothers lost their virginity an average of more than a year later (at age 18.3) than girls with younger sisters only. Girls with both younger brothers and sisters lost it nearly two years later on average (age 19.3) than girls with no younger siblings. Younger sisters alone had no impact.

The chastity effect only applied to girls with younger brothers. Having a big brother (or sister) didn’t make a girl any less likely to hold onto her virginity, yet another strange pattern emerged. This one involved the girls’ physical maturity.

The more older brothers a girl had, the later she got her first period. Girls with only elder brothers got their first visit from “Aunt Flo” up to a year later (at age 13.6) than girls with older sisters or no older siblings (age 12.7). (This is meaningful given that breast cancer and other conditions are related to earlier menstruation.)

Elder brothers delay physiological maturation, while younger brothers delay behavioral maturation.

What’s going on?

Trained as behavioral ecologists, Milne and Judge took a look at the big picture. Daughters are often caregivers. Historically, as has been found in traditional societies, a woman with daughters as first- or second-born children has a larger family than a mom whose first children were sons. Elder daughters take care of younger siblings, which frees up Mom to keep popping them out. Boys historically required more resources than do girls, which made big sister’s contributions even more important. As a result, these helpful elder daughters experience a delay in starting their own families. In the modern world where women don’t usually start their families until their mid-twenties on average, this is no problem, but in the past females with brothers may have had fewer children over their lifetimes.

The bigger mystery is what’s actually behind Big- and Little Brother’s stalling effect on their sisters’ sexuality. This is unknown territory, so Milne and Judge tread lightly here. The safest theory is that the delays are behavioral. Girls with little brothers lose their virginity later because they’re too busy taking care of their siblings to have love lives of their own. Perhaps little brothers, who are slower than female siblings to develop and reach puberty, keep their elder sisters in a more childish mindset. Or perhaps the stress of care-giving slows down puberty.

The researchers should also consider a much more surprising yet equally plausible theory: brothers send out chemical cues (pheromones) in their sweat that inhibit their sisters’ sexual development. Odd as it sounds, this would explain the perplexing finding that girls with older brothers get their first periods later than their peers. And, it appears, so do girls who grow up with their biological fathers in the household, compared to their peers with absent dads. Several studies, including here and here and a large one at Penn State that involved over nineteen hundred college students, came to this conclusion. (Interestingly, the same study found that girls growing up in homes with males unrelated to them got their periods earlier than average.)

The sweat-stifles-sexuality theory isn’t as far-fetched as it sounds. Other animals — rodents, for instance — use pheromones to modulate sexual maturity and fertility in a population. Over the years, a girl would inhale chemical cues in fraternal sweat — think of all those sock and armpit odors. Those chemicals would hit the hypothalamus of her brain where sex hormones are produced, and slow down the works. Puberty strikes a little later. Evolutionarily speaking, the result is that a girl could stay in the family nest longer without conflict. The risk of incest is reduced.

So should I try for son now? Truth is, the data applies to populations, not individuals. There are no guarantees; these are just interesting findings that deserve more research. Moreover, I’m in over my head right now with my baby girl’s teething and feeding challenges. Sure, I’ll want preserve her girlhood for longer than a New York minute. But I also need to preserve my sanity

 

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