Baby girls feel discomfort more acutely than boys do, so they're more likely to fuss when they get cold or have a wet diaper. But don't be too quick to label your little princess high-maintenance; her keener sense of touch also makes her more responsive to cuddling and easier to soothe.
Girls tend to produce more oxytocin, the human-bonding hormone, and serotonin, a "feel-good" hormone. This helps explain why they're more apt to be caregivers to dolls and younger siblings. Little boys really are more interested in toy cars, trucks, and other things that move.
"Boys tend to explore their world more physically than girls do, such as by banging their toys, jumping, and playing rough. "They have an unrestrained way of expressing energy," says Adie Goldberg, coauthor of It's a Baby Boy! and It's a Baby Girl! Play is calmer among girls, who tend to stay closer to adults, engage in fantasy, and hang out in small groups, whereas boys gravitate toward packs of playmates and intense, active games.
Baby girls are five times more likely than boys are to get hemangiomas, raised red birthmarks caused by a buildup of blood vessels. They usually disappear by age 9 but can be treated with steroids or removed by lasers.
Baby boys are at higher risk for hernias. That's because when they're in utero, their testicles descend from the abdomen, which can leave a cavity in the groin that requires surgery to repair.
Baby girls are four times more susceptible to hip dysplasia, a dislocation of the thighbone from the hip socket. Braces can usually remedy the condition.
Boys more often have asthma, yet they're more likely than girls to outgrow it by adolescence. One possible explanation: Higher testosterone levels might relax airway muscles.
Girls are more prone to UTIs. Their urinary tract is shorter, so it's easier for bacteria to reach their bladder and cause an infection
Boys often have stronger motor skills — think jumping and climbing. They might also master tasks like aiming a throw and building block towers at a younger age than their girl peers do, probably because the area of a boy's brain that's devoted to visualspatial relation is larger. But...
...Girls can kick serious butt when it comes to fine motor skills: They pick up finger foods earlier on and, when they're older, learn to write and tie shoes sooner.
Girls generally are toilet trained earlier than boys are. They typically master the potty at about 35 months, whereas boys tend to start using the potty at around 39 months. There are loads of theories as to why girls get a head start. One popular explanation: Mommy's "plumbing" is the same as her daughter's, and she often does most of the teaching.
Boys are late growers: They usually don't reach 50 percent of their adult height until about 24 months; girls can reach that mark at only 20 months. Boys also enter puberty roughly two years later than girls do and tend to continue shooting up for three more years.
Girls talk it up earlier than boys do, thanks to their more efficient use of the language centers in both hemispheres of the brain. At 18 months or so, a girl's vocabulary consists of about 90 words, compared with 40 words for most toddler boys. But by age 3, boys are usually just as skilled in the gift of gab.