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WEDNESDAY, Jan. 28 (HealthDayNews) -- What a mother eats can affect how long her offspring live, at least when it comes to mouse pups.

Although maternal diet clearly affects children's health, it's not clear if these specific findings, appearing in a brief in the Jan. 29 issue of Nature, can be extrapolated to humans. But they do suggest that pregnant mice on a low-protein diet, which may not meet their nutritional needs, give birth to small, undernourished offspring with shortened life spans.

The study authors looked at three different groups of mouse mothers.

One received a normal diet made up of 20 percent protein through pregnancy and breast-feeding. Their children lived for about two years.

Another group of mothers was fed normally during pregnancy but then given a low-protein diet -- approximately 8 percent -- while breast-feeding. After weaning, the pups were then given a high-sugar "cafeteria-style" diet consisting largely of sweetened condensed milk that mice apparently find very tasty. Those mouse pups lived an average of two months longer than the first group.

The third group of mothers received a low-protein diet while pregnant followed by a normal diet while lactating. Their offspring died six months earlier than the ones in the first group. When these pups were fed a cafeteria-style diet high in sugar they died even sooner.

"If you just have the low-protein diet during lactation and a normal diet during pregnancy, that really slows down the growth and those animals live substantially longer," says study author Susan E. Ozanne, a research fellow at the University of Cambridge in England.

"What's even more surprising is that if you then give them this cafeteria-style, highly palatable diet, they're protected from the detrimental effects of that diet. They still live longer," she says.

"A low-protein diet causes mild growth restrictions, then the mice undergo rapid catch-up growth during lactation period. They grow very quickly then die younger than the offspring of completely normally fed mums," Ozanne says. "Being over-nourished during the lactation period or growing very quickly is not a good thing in the mouse."

The reasons for these differences aren't entirely clear.

"We think it might be at least in part due to the long-term differences in appetite," Ozanne says. "If you are born small and then grow very quickly during lactation, you have a permanently increased appetite, whereas if you go nice and slowly, your appetite is permanently reduced so you're self-regulating and not so prone to obesity. It may well also alter your propensity to exercise."

Caution is needed in extrapolating these findings to humans. "You always have to take care when you've got data from rodent models," Ozanne says. "Now we need to see if the same mechanisms are operating in humans but certainly we have an indication that they may well be."

Research has shown that human infants who are breast-fed are less likely to become obese.

Dr. Gene Burkett, a professor of obstetrics and gynecology at the University of Miami School of Medicine, says he doesn't know of any research in humans that mirrors the Ozanne study.

"What we do have is considerable data that tells us that maternal nutrition can have a great effect on the obesity of a child and particularly in women who have a reduced amount of food intake," he says.

Although the data is preliminary, it does suggest that pregnant women who are underweight and who eat inadequately produce small babies who eventually become fat. The explanation could be that the fetus has "eat as much as you can" signals turned on while still in the womb, and that these signals stay turned on after birth, Burkett says.

There's also evidence that overfeeding a newborn can promote obesity regardless of what the maternal nutrition is, Burkett says: "Where one starts and one ends is really the problem."

More information

The March of Dimes has more information on eating while you're pregnant and on breastfeeding.

(SOURCES: Susan E. Ozanne, Ph.D., research fellow, University of Cambridge, Cambridge, England; Gene Burkett, M.D., professor, obstetrics and gynecology, University of Miami School of Medicine, Miami; Jan. 29, 2004, Nature)

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