only the mother's biological clock matters:
wrong. sorry guys, but you have biological clocks, too. scientists have long known that a woman's advancing age brings decreased fertility and increased risk of having a baby with chromosomal disorders such as down's syndrome, says joshua copel, an obstetrician–gynecologist at yale maternal-fetal medicine in new haven, conn. (the odds of a woman under 30 having a down's child is less than one in 1,000, but by the time she is 35, it increases to one in 400; and when she reaches 42, her chances are one in 60, according to the national institute of child health and human development.) men can produce sperm throughout their lives, which means they can father children at any age. but there is evidence that older dads are also more likely to pass on genetic defects to their offspring, according to copel. studies suggest that 2 percent of infants with dads age 50 or older will develop the neurological disorder schizophrenia—that's three times the incidence among kids fathered by men in their early 20s. and some research suggests that fathers age 40 or older are six times more likely than those under age 30 to have kids with autism spectrum disorder.
fat pregnant women are more likely to have overweight babies:
according to robert zurawin, an obstetrician–gynecologist (ob–gyn) at baylor college of medicine in houston, overweight or obese mothers-to-be are more at risk than normal-weight ones of having big babies. the reason, he says: heavy women are more likely to have type 2 diabetes or to develop gestational diabetes (which occurs during pregnancy and usually passes after the baby is born). these diseases, in which the body has trouble using the hormone insulin, hinder cells' ability to absorb glucose, their primary energy source. as a result, the mom's blood contains excess glucose (also called high blood sugar), which passes to the fetus via the placenta, says zurawin, adding "it's like the baby's eating ice cream all day long."
bump in the front? it's a boy:
if the fetus is male, the mom carries most of the weight low and in the front, like a basketball shooting from her hips; if it's a girl, the mother looks more like a planet, round all over—or so they say. "that's clearly a myth," says george saade, chief of maternal-fetal medicine at the university of texas medical branch (u.t.m.b.) in galveston. how much the belly sticks out depends largely on how far the abdominal muscles flanking the left and right sides of the belly separate and relax, saade explains. and how high or low the belly sits depends on how much the pelvic joints loosen (thanks to a hormone called relaxin, produced by the ovaries mainly during pregnancy), thereby making more room for the baby to drop into the pelvis, he adds. another factor influencing belly shape, he says, is the position of the fetus, which varies throughout pregnancy. the belly will appear wider, for instance, if the fetus is lying horizontally rather than vertically.
pregnant women should avoid peanuts because they up the baby's odds of developing an allergy to them
there is no compelling scientific evidence that eating peanuts, shellfish or other potentially allergenic foods during pregnancy affects the baby's risk of developing allergies, according to aziz sheikh, a community health scientist at the university of edinburgh in scotland who has studied childhood allergies. u.t.m.b.'s saade concurs. "for an allergen to affect the baby during pregnancy," he says, "it has to get into the mother's [blood] and then cross the placenta in a form that remains allergenic." but, he notes, the mother's metabolism might break down food allergens into nonallergenic components (such as amino acids and short chains of amino acids) before entering her bloodstream and reaching the fetus.
a fetus with a full head of hair spells heartburn for mom:
a few years ago, researchers from johns hopkins university (j.h.u.) in baltimore decided to put this myth to rest with a scientific study, but they didn't get the results they were expecting. the researchers asked 64pregnant women—all in their third trimester—to rate the severity of their heartburn, and then compared the hair volumes of their infants within two weeks of birth. their findings, published in the journal birth: 23 out of 28 (82 percent) of the women reporting moderate or severe heartburn gave birth to babies with average or above average amounts of hair; only 11 out of 36 (31 percent) of those with mild or no heartburn produced babies with luxuriant locks. study co-author janet dipietro, a developmental psychologist at the j.h.u. bloomberg school of public health, cautions that the study was small and does not establish a definitive link between heartburn and fetal hair. but if there is one, she suspects pregnancy hormones such as estrogen and progesterone might be to blame. she says the same hormones that stimulate fetal hair growth might also relax the esophageal sphincter, the muscle in the esophagus that normally tightens after meals, allowing stomach acids to flow up into the esophagus and cause heartburn (acid reflux).
lifting heavy objects could cause the placenta to rip from the uterine wall:
lifting something cannot not cause the placenta to shear from the wall of the womb, cutting off the supply of nutrients and oxygen to the fetus, saade says. the concern with lifting, he says, is that the mother could injure her back or lose balance and topple over. being pregnant, especially during the final months, is like carrying a bag full of groceries all day—extra weight in the front that shifts the woman's center of gravity and makes it harder to balance, thereby putting stress on the spine, along with increasing her risk of falling. lifting something heavy only adds more to that stress, saade notes, upping the chance of back injuries such as pulled muscles.
women eat more when expecting a boy:
in 2003 a team of researchers from the u.s. and europe studied the diets of 244 pregnant women during their second trimester and found that those carrying male fetuses ate, on average, 190 more calories per day than those carrying females. those extra calories apparently made a beeline for the fetus, because the boy babies were heavier and their mothers did not pack on any more pounds than those carrying girls. "we found that birth weight of boys was on the average higher than that of girls," says senior author dimitrios trichopoulos, an epidemiologist at the harvard school of public health in boston. "our interpretation is that boys are somehow programmed to be heavier than girls, and this requires higher caloric intake from the mother," he adds, speculating that testosterone from the fetal testicles might be involved in increasing the maternal appetite.
原文链接：
1、只有妈妈的生物钟会对胎儿有影响
这是错误的，爸爸们，你们也有生物钟。科学家早就发现，女人的年龄越大，不孕不育的风险和婴儿感染染色体疾病（唐氏综合症）的风险就越大，康涅狄格州纽黑文耶鲁母胎医院妇产科医生joshua copel说。（据美国国立儿童健康与人类发展协会的调查，30岁以下女性生下的小孩患唐氏的比例小于千分之一；但到35岁，这个比例是四百分之一；到42岁，这个比例达到六十分之一。）男人一辈子都能产生精子，这意味着他们在任何年龄都能做父亲。但有证据表明，年龄较大的爸爸更可能传递遗传缺陷给它们的后代。研究表明年龄超过50岁的父亲的婴儿中有2%将患神经紊乱精神症——这是父亲在二十多岁就生下的婴儿的发生率的三倍。另外有些研究也表明40岁以上的父亲比 30岁以下的父亲更可能生有自闭症谱系障碍的小孩。
2、胖孕妇更可能生超重婴儿
据休斯顿baylor医学院妇产科医生robert zurawin研究，超重或肥胖的孕妇比正常体重孕妇生大个婴儿的风险大。至于原因，他说：肥胖女性更可能得2型糖尿病或妊娠期糖尿病（发生在怀孕期间，通常在宝宝出生后消失）。这些疾病，阻碍细胞对葡萄糖的吸收，使人体无法使用胰岛素，而葡萄糖是基本能量来源。结果，妈妈的血液里含有过量葡萄糖（也称为高血糖），通过胎盘输送给胎儿，zurawin补充道：“这就像整天给胎儿吃冰淇淋。”
3、肚子前面凸，是男孩？
如果胎儿是男的，妈妈承受的重量比较低而且在前方，像一个从她的臀部投篮的球。“这完全是误传，”加尔维斯敦德州大学医疗分部母胎医学行政长官george saade说。腹部伸出多远很大程度上取决于肚子左右两侧腹部肌肉侧翼的分开和放松程度，saade解释道。腹部位置的高或低取决于骨盆关节松动程度（由于荷尔蒙唤起耻骨松弛激素——主要是怀孕期间卵巢产生的），从而有更多的空间把婴儿丢进骨盆内，他补充道。他说，另外一个影响腹部形状的因素是胎儿的位置，在整个怀孕过程中位置是不同的。比如，当胎儿水平横卧着而不是自立的时候，孕妇的腹部可能比较宽。
4、孕妇不应吃花生，因为这会增加宝宝对花生过敏的可能性
根据苏格兰爱丁堡大学研究儿童过敏的社区卫生科学家aziz sheikh的研究，没有确切的依据证明孕期食用花生、贝类或其他会引发过敏的食物会增加小孩以后对这些食物过敏的可能。u.t.m.b.的 saade同意这一说法。“对于在怀孕期间影响婴儿的变应原，”他说，“它需要渗入母体的血液，然后以仍然可能引发过敏的形式穿过胎盘。”但是，他提示道，母体的新陈代谢可能在食物过敏原进入血液、到达胎盘前，把它们分解成不会引发过敏的成分（比如氨基酸和短链氨基酸）。
5、头发浓密的胎儿会导致妈妈胃灼热
几年前，巴尔的摩约翰.霍普金斯大学的研究人员试图依据一项科学研究来定位这个传言，但他们没有获得预期想要的结果。研究人员询问了64名孕期女性 ——都有6到9个月身孕——以评估她们胃灼热的严重性，然后比较了在两个星期内出生的婴儿的头发浓密度。他们的研究结果，发表在birth杂志上：生下头发浓密婴儿的女性中82%有中度或重度胃灼热，只有31%的女性有轻微或没有胃灼热。研究的合作者——j.h.u.彭博公共卫生学院发展心理学家janet dipietro警告说，这个研究的个体数量太少，不能确切证明头发多少与胃灼热的关系。但是，如果真的有关系的话，她怀疑妊娠激素，如雌激素和黄体酮可能要承担全部责任。她说，刺激胎儿头发生长的激素也可能使食道括约肌松弛（这个在食道的肌肉饭后通常会收缩），使胃酸流入食道，从而导致胃灼热。
6、举重物可能导致胎盘从子宫壁撕裂
举重物可能导致胎盘从子宫壁剥离，从而切断对胎儿养分和氧气的供应，saade说。但他说的对举重物的担心是母亲可能扭伤腰部或因失去平衡而摔倒。怀孕，尤其是在最后几个月里，就像是整天带着一个装满杂货的袋——前面过多的重量使女性的重心改变，让她们难以保持平衡，更多的重量压在脊椎上，伴随的是越来越多的摔倒风险。saade提示：举重物只是增加了脊椎承受的重量，增加后背肌肉拉伤的风险。
7、想要生男孩妈妈就要吃得多
2003年美国和欧洲的一组研究人员研究了244位怀孕女性孕期4到6个月的饮食，发现平均而言，那些怀男胎儿的女性比怀女胎儿的每天要多摄入190多卡的热量。这些多出的热量显然直接输送给胎儿了，因为男婴儿较重，而且他们的母亲不比任何怀女孩的女性增加了任何体重。“我们发现，男孩出生时的体重平均高于女孩，”波士顿哈佛公共卫生学院流行病学家、资深作者 dimitrios trichopoulos说。“我们的解释是，男孩从某种程度上来说，体重比女孩重，这需要从母体摄取较多的卡路里，”他补充道，据猜测，男胎儿睾丸的睾酮激素可能是刺激孕妇胃口的一个因素。