科学告诉你：关于怀孕的这些老话居然不是迷信

Most of the folk wisdom that well-meaning older relatives offer up to expectant mothers can be easily ignored: Carrying the baby lower in the abdomen isn't a sign that it's a boy, or a girl, or anything other than an indication your abdominal muscles have loosened up a bit.
大多数长辈好意传授给准妈妈的民间智慧很容易被击破：例如，通过婴儿是否在肚子下方的迹象并不能说明他是男孩还是女孩，或者其他什么东西，这只能说明你腹部的肌肉有点松弛。

Your cravings won't manifest themselves as birthmarks on the kid's skin. Long walks won't induce labor.
你的生理欲望不会变成孩子皮肤上的胎记。长时间的散步也不会助产。

And no, the full moon has nothing to do with the timing of the birth.
并且满月与婴儿的出生时间毫无关系。

But in recent years, a handful of studies have found that some of the most outlandish old ideas concerning babies and pregnancy may have some scientific merit after all.
不过，近几年有大量的科学研究发现一些有关婴儿和怀孕的奇怪旧观念还是有一定科学道理的。

Here are a few that superstitious grandmothers everywhere can put in the win column.
下面就是一些我们的迷信祖母的正确观念。

A long, difficult labor means the baby's a boy
分娩的过程要是痛且长，就意味着婴儿是男孩

Researchers aren't quite sure why this one's true, but nonetheless: In 2003, a team of doctors analyzed more than 8,000 births at a single hospital in Ireland between 1997 and 2000, excluding women who delivered prematurely or needed to induce labor. When they crunched all the numbers, the difference between the sexes was small but noticeable.
尽管研究人员仍不太清楚为什么这个观念是正确的，但事实就是这样：2003年，一组医生分析了来自同一家爱尔兰医院的8000多名新生儿的资料，这些新生儿都出生在1997年至2000年间，并且排除掉了早产以及引产出生的婴儿。当这些医生分析所有数字后发现，分娩男婴女婴的差别虽然很小，但可以发现一条明显的规律。

On average, labor for boy births lasted a little over six hours, while girl births took a little under six. Women delivering boys were also more likely to run into complications during delivery, requiring C-sections 6 percent of the time (compared to 4 percent for girls) and forceps in 8 percent of cases (as opposed to 6 percent).
平均来说，母亲生男孩的时间持续六小时多一点，但生女孩的时间会略短于六个小时。在分娩过程中，生男孩的母亲分娩时发生并发症的可能性更大，剖腹产的比例是6%（生女孩的为4%），使用助产钳的比例是8%（生女孩时为6%）。

Overall, 29 percent of boy deliveries ended up requiring some sort of extra intervention; for girls, it was 24 percent.
总的来看，在生男孩时，有29%的母亲需要某种医疗介入；而生女孩时，这个数字为24%。

One possible reason for the discrepancy: Boys, on average, weigh three and a half ounces more at birth than girls do. And a small 2003 study found that women carrying boys also consume more calories during pregnancy, suggesting that male babies are a little more demanding even before delivery starts.
分娩差异的一个可能原因是：男孩出生时的体重平均比女孩多99克（3.5盎司）。2003年的一项小型研究发现，怀男孩的母亲在怀孕过程中会消耗更多的卡路里，这也表明，甚至在分娩之前，怀男孩就更吃力一点。

To have a girl, stay away from bananas
要是想要一个女孩的话，就不要吃香蕉

It's not just that women carrying boys will eat more; eating more in the lead-up to pregnancy may also make it more likely that the baby is a boy.
准妈妈在怀男孩时吃得更多，不仅如此，在怀孕前夕吃得多的女人也更可能生男孩。

In 2008, a study published in the journal Proceedings of the Royal Society asked 740 women who were pregnant for the first time to describe their diets over the year before they conceived, then divided them into three groups based on calorie intake.
2008年，一项发表在《英国皇家学会期刊》上的研究对740位初次怀孕的女性进行了调查分析。研究人员让这些女性描述她们在怀孕前一年里的饮食情况，然后再根据热量摄入将她们分成三组。

The women in the top third of the study, calorie-wise, had boys 56 percent of the time; among the third that consumed the fewest calories, 55 percent had girls.
从热量排行来看，最靠前的三分之一中有56%的母亲怀的是男孩；摄入热量最少的那三分之一中有55%的母亲怀的是女孩。

Here's where the old line about bananas -- that eating them before conception will up your chances of having a boy -- comes in. The study authors found that sheer calorie intake wasn't the only thing that made a difference; specific nutrients did, too.
有关香蕉的老观念来了——据说在怀孕前吃香蕉会增加你生男孩的几率。研究作者发现，摄入卡路里总量并不是造成差异的唯一因素，生男生女也与特定的营养元素有关。

Eating plenty of potassium (which bananas are chock-full of) was linked to boys, as were diets high in calcium and sodium.
从饮食中摄入大量的钾（香蕉富含钾）、钙和钠会提高生男孩的几率。

Though as the Guardian noted, overhauling your diet to influence the sex of a future kid can be a risky move, health-wise, spurring people to overload on some nutrients and to ignore others -- a safer idea may be to focus on eating healthily in general, and leaving the rest up to chance.
虽然正如《卫报》所指出的那样，从健康角度来看，调整准妈妈的饮食以影响未来孩子的性别可能是一项有风险的举动，这会促使人们过量摄取某些营养素，而忽略其他营养物质——更安全的做法是，多多关注饮食健康，剩下的就由上天决定吧。

Heartburn is a harbinger of a hairy baby
胃灼热是毛发旺盛的宝宝的预兆

Here's a horrifying fact about babies: Sometime in the second trimester of pregnancy, they develop a coat of fine hair all over their bodies, called lanugo -- and sometime in the third trimester, they shed it and eat it. A baby's first poop, in fact, is the digested remains of their own body hair.
一个关于婴儿的可怕事实是：有时在第二孕期，婴儿会全身覆盖着一层细毛，这被称作胎毛。在第三孕期，胎毛会脱落，婴儿会把它们吃掉。所以事实上，婴儿的初次排便就是他们消化掉的胎毛。

The hair on their heads, though, is another story. While all babies have lanugo in the womb, not all babies are born with anything up top -- and mothers looking to know ahead of time whether their kid will be fuzzy-headed or bald may be able to use their own heartburn as a clue.
婴儿的头发又是另一个故事了。虽然所有的胎儿在子宫内都会长出胎毛，但不是所有的胎儿一出生就会有头发，因此，妈妈可以通过胃灼热这个迹象来提前知道她们的孩子会毛发茂盛还是稀疏。

In 2006, for a study in the journal Birth, a team of researchers from Johns Hopkins University followed 64 women throughout their pregnancies, 28 of whom reported moderate or severe heartburn.
2006年，约翰霍普金斯大学的一组研究人员在《生育》杂志上发表了一项研究，他们跟踪调查了64名女性的孕期生活，其中有28人报告称有中度或严重的胃灼热。

Within that group, 23 women ended up having babies of average or above-average hairiness. On the opposite end of the spectrum, of the 12 women who reported no heartburn at all, ten of them gave birth to kids who were less hairy than the average newborn.
在这28名女性中，有23名女性生出的婴儿的毛发量达到或者高出平均水平。另一方面，报告中12名没有出现胃灼热现象的女性中，有10名女性生出的婴儿毛发量低于平均水平。

But here's a perfect example of correlation not equaling causation. The heartburn wasn't a result of the hair, or vice versa. Rather, the study authors argued, both were caused by a third factor: pregnancy hormones.
不过，这个是相关性的典例，而不是因果关系的典例。胃灼热的产生不是因为婴儿毛发的生长，反之亦然。实际上，研究作者认为，这两者都是由第三个因素引起的：孕激素。

Specifically, the same hormones that contribute to hair growth in the womb have also been shown to relax the muscles that keep stomach acid contained in the stomach.
具体来说，在子宫里促使婴儿毛发生长的激素也同样会使胃里控制胃酸的肌肉松弛。

So you can technically blame the baby for that fiery pain in your chest, but the link isn't quite as direct as the old wives' tale implies.
所以在理论上你可以责怪婴儿，因为他们让你胸口灼热，但这两者之间的联系没有像长辈的所说的那么直接。