Mothers who eat junk food during pregnancy and while breastfeeding have obesity-prone children, rat studies suggest.

Once weaned, the offspring of junk-food-fed mothers prefer junk foods more than the offspring of rats fed a healthy diet during pregnancy.

But even when fed a healthy diet, the offspring of the junk-food-fed mothers are fatter than the offspring of rats fed healthy food. Moreover, obesity-linked genes are more active in the offspring of junk-food-fed mothers -- especially female offspring.

"The maternal diet seems to influence and trigger events early in the life of their offspring," study researcher Stephanie Bayol, PhD, tells WebMD. "We found that by the end of their adolescence, the offspring from the junk-food-fed animals had increased blood sugar, blood fat, and decreased insulin sensitivity -- all of which are associated with overweight and diabetes."

Bayol and colleagues at London's Royal Veterinary College gave pregnant rats normal rat chow. But they also gave them free access to cookies, chocolate, doughnuts, muffins, potato chips, candy, and cheese.

In earlier studies, they showed that the offspring of these rats liked high-fat, high-salt, high-sugar foods better than other rats. But the new studies show that even when never fed junk food themselves, the rats whose mothers ate junk food during pregnancy grew up fatter than normal rats.

"Their fat cells were larger, which might make them more prone to obesity and might make it harder for them to lose weight," Bayol says. "So there were lasting effects from their mother's consumption of junk food, even if they were not fed junk food after weaning."

Interestingly, the effects seem to be stronger for female offspring than for males.

"Males seem to use a different molecular machinery to regulate fat storage than do females," Bayol says.

Does the same thing happen in humans? Of course, it would be unethical to feed junk food to pregnant women. But there's evidence that women's diets during pregnancy and breastfeeding affect their children's food preferences, says pediatrician Stephen R. Cook, MD, MPH, of Golisano Children's Hospital at the University of Rochester, N.Y.

"This gets to the concept of fetal programming. A lot of information suggests that in-utero exposures can lead to long-lasting effects in children," Cook tells WebMD. "Women who smoke during pregnancy have children who are heavier, so maternal patterns can affect a child's weight. Whether the cause is altered metabolism or something else, it is a very real concern."

On the other hand, Cook says, junk food is made to have tastes and textures that appeal to children. And it's heavily advertised, which also affects a child's preferences.

對老鼠的研究使人聯想到：母親在懷孕期間以及在哺乳時食用垃圾食品，可能造成有肥胖傾向的孩子。
一旦斷奶，用垃圾食品喂養的母親的后代，比在懷孕期間喂以健康飲食的老鼠的后代，更喜歡垃圾食品。

但是即使在喂以健康飲食時，用垃圾食品喂養的母親的后代也比喂以健康飲食的老鼠的后代更肥胖一些。此外，在用垃圾食品喂養的母親的后代中，與肥胖相聯系的基因更為活動——尤其是雌性的后代。

“母方的飲食似乎在她們后代生命的早期就影響和觸發事件的發生，”研究員斯蒂芬 貝約爾博士告訴 WebMD（網絡醫學博士）說。“我們在牠們的青春期結束之前發現，用垃圾食品喂養的母親的后代具有增高的血糖、血脂以及降低的胰島素敏感性——所有這一切都與超重和糖尿病相關。”

貝約爾和他在倫敦皇家獸醫學院的同事們給孕鼠喂食正常的鼠食。但是他們也給了牠們自由接近餅干、巧克力、炸面圈、松餅、薯片、糖果和奶酪的機會。

在早期的研究中，他們展現出，這些喜歡高脂肪、高鹽、高糖食物的老鼠的后代優于其他的老鼠。但是新的研究顯示，即使在從未喂食過垃圾食品時，那些牠們的母親在懷孕期間食用過垃圾食品的老鼠，也比正常的老鼠長得肥胖一些。

“牠們的脂肪細胞較大，這可能使牠們更容易肥胖，并且可能使得更難以為牠們減肥，”貝約爾說。“因此，即使牠們在斷奶后沒有喂過垃圾食品，還是有持久的影響來自牠們母親對垃圾食品的消費。”

有趣的是，這種效果對于雌性后代似乎比雄性后代更強一些。

“雄性似乎使用與雌性不同的分子機制來調節脂肪的儲存，”貝約爾說。

同樣的事情在人類中發生嗎？當然，給孕婦進食垃圾食品會是不道德的。但是，紐約州羅徹斯特大學哥里薩諾兒童醫院的兒科醫生、醫學博士、公共衛生碩士斯蒂芬 R. 庫克說，有證據表明，婦女在懷孕和哺乳期間的飲食，影響其子女的食物偏好。

“這一下子就談起了胎兒設計的概念。很多資料表明，在子宮內的暴露接觸可能導致對兒童長期持久的影響，”庫克告訴 WebMD。“在懷孕期間吸煙的婦女就有較重一些的子女，所以，產婦的模式可能影響兒童的體重。是否因為代謝改變或者某種其它的原因，這是一件很值得實際關注的事情。”

在另一方面，庫克說，垃圾食品做得具有吸引兒童的味道和質地。而且它大量地做廣告，這也影響到孩子的喜好