Another baby? Not until you're back to your prepregnancy weight, medical experts advise.

Overweight moms who conceive before shedding those extra pounds face health risks for themselves and their infants, according to research reported in The Daily Telegraph.

Babies whose moms are overweight may grow too large in the womb, which can increase the risk of stillbirth as well as permanent muscle damage if the baby's shoulders get stuck during labor, according to new guidelines from a British government health group.

Obese women also can give birth to infants with a very low birthweight and such moms have a higher incidence of gestational diabetes, according to the group, the National Institute for Health and Clinical Excellence.

"The increasing prevalence of obesity among pregnant women in the U.K. is very worrying as there are so many potential risks for the mother and her baby," said Prof. Lucilla Poston, co-author of the guidelines and director of maternal and fetal research at King's College London, according to The Daily Telegraph. "Even modest weight retention after pregnancy is now known to increase the risk of problems in the next pregnancy."

NICE did not recommend that obese women try to diet during pregnancy, though, because that could pose a health risk to the unborn baby.

New World Health Organization guidelines say that women increase their chances of becoming obese by gaining weight over a series of pregnancies unless they lose the excess pounds after each baby.

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