Low-Calorie Diet Can Cause Premature Births

A study on sheep may help explain why preterm births occur in humans--sheep fed a low-calorie diet tend to have a higher risk of premature delivery, according to a study.

Ten sheep were fed a diet meant to lower the animals’ body weight by 15 percent--defined as mild to moderate nutrient restriction--prior to mating and for the first part of pregnancy. The sheep were fed normally for the remainder of pregnancy.

Sheep on the restricted diet delivered lambs an average of seven days earlier than sheep fed a normal diet.

The reason why this effect occurred is not known, however researchers suggested that the mother may send a signal to the embryo letting it know that the nutritional environment is poor, and the embryo may modify growth rate and length of gestation accordingly.

It also appeared that a lack of nutrients accelerated the development of the lambs' adrenal glands, which may trigger birth by stimulating the release of hormones.

It does not appear that the effects of being undernourished during conception can be reversed by eating more during pregnancy, according to researchers.

Premature birth, which is the number one cause of death among newborn babies, is associated with a greater risk of mental and physical problems.

As the study results indicate that even modest restrictions in diet around the time of conception can lead to premature birth, researchers suggest that women of childbearing age should eat a healthy, balanced diet and should not diet substantially before the start of pregnancy.

Science April 25, 2003;300:606