Womb for improvement

Einstein wannabes should choose their mothers with care

New Scientist, 07 March 1998

BETTER wombs can produce smarter kids, scientists in the US suggest. Their work shows that genetically identical mouse embryos implanted in different wombs end up performing differently at mental tasks. This is the first time that the uterus itself has been clearly implicated in an offspring's long-term cognitive abilities, they say.

Victor Denenberg and his colleagues at the University of Connecticut in Storrs and the Jackson Laboratory in Bar Harbor, Maine, raised a strain of mice that suffers from an autoimmune disease rather like lupus in humans. The brains of around half these mice have slight structural deformities which bear a striking resemblance to structural abnormalities found in the brains of human dyslexics, says Denenberg.

The researchers wanted to test their hypothesis that time spent in the wombs of mothers with autoimmune disease could have a negative effect on performance. Using a genetically identical group of mouse embryos from the autoimmune strain, they transplanted one-third into the uteri of mothers from a strain that was unaffected by the disease.

Another third, controlling for the effects of surrogacy, were transplanted into the wombs of other autoimmune mothers. The others were allowed to gestate normally. All were raised from birth by mothers from the strain not affected by autoimmune disease.

Once they had been weaned, the mice were put through a battery of five learning tests. In one test at 10 weeks, for instance, they had to learn which way to turn in a maze filled with cul-de-sacs. In another at 11 weeks they had to find a submerged platform while swimming in a tub of water. Later, at 12 weeks, they had to work out how to avoid getting a light electric shock.

All the mice showed competence in learning, but in four of the five tests, the mice that developed in the womb of a mouse with no autoimmune disease did better—even if they had inherited the brain abnormalities associated with the autoimmune disease. "Presumably the anomaly acts to impair the behaviour of the mouse," says Denenberg. But gestation in the hybrid uterus seems to mitigate the problem, he says. "We're delighted that we've found some positive contributions."

Denenberg thinks that the difference could be due to some subtle biochemical factors in the uterus. He believes that every mother may affect her offspring in slightly different ways. "The uterine environment can have long-term broad and beneficial behavioural effects," the team says in last week's issue of the journal Neuroreport(vol 9, p 619).

Denenberg expects the study to raise interesting questions about surrogate motherhood in humans and even the prospect of artificial wombs. But more importantly, it may highlight the contribution that good general maternal health can have on cognitive abilities. "Maybe we ought to think more seriously about the physiology of gestation," he says. "Are there ways to prepare a non-pregnant uterus for pregnancy? An `operation head-start' for the uterus?"