You think you had an unhappy childhood? Maybe you just had a bad "wombhood." That's right. Now you can blame your woes on your prenatal passage. You didn't get what you needed from your mom as a fetus. That's why you're fat in middle age. Why you develop heart disease, diabetes and even cancer. Not to mention how you handle stress.

This expanded view of the womb grows out of research compiled in a new book entitled "Life in the Womb: The Origin of Health and Disease," by physician Peter W. Nathanielsz. A kind of scientific "Wombie Dearest," the book argues that conditions in the womb set the fetus up for a range of health problems later in life--from heart disease and allergies to cancer and obesity. If a mother doesn't get enough to eat in the first trimester, Nathanielsz asserts, the fetus is likely to become an obese adult. It's as though you spend your adult life overcompensating for what you didn't get in the womb.

The buzzword is fetal programming, a womb-determinism theory of disease and development. "You pass more biological milestones before you're born than after," says Nathanielsz, a professor of reproductive medicine at the College of Veterinary Medicine at Cornell University. "What happens to you in the womb can program your health for a lifetime."

In other words, you are not just what you eat--but what your mom ate, too.

But before you call up your mother and chew her out for not eating more vegetables, take a deep breath. The problem with wombism is oversimplification.

To be sure, mothers and doctors have known for eons that the womb is an important place. Common sense and public policy urge pregnant women to get proper nutrition and prenatal care. Specialists have come a long way to shepherd high-risk pregnancies, and there's good research on the consequences of exposing the fetus to toxic substances such as alcohol or tobacco or drugs that can cause birth defects.

But the idea that subtle conditions in the womb may determine a person's health status in later life is new--and pretty controversial. It's the latest salvo in the nature-nurture debate and correctly attacks the popular view that everything from heart disease to humor is determined by genes. It's not all in the genes, argue the advocates for fetal programming.

But it's not all in the womb, either.

Adult diseases such as diabetes, hypertension and cancer are rooted in many factors, reflecting an intricate dance over many years between genes and environment. Conditions in the womb may play a role, but in common complicated diseases, there usually is no one culprit.

Nathanielsz offers some tantalizing clues: A low birth-weight baby has a greater risk of eventually developing high blood pressure and heart disease. But a girl who weighs close to nine pounds at birth has a higher risk of breast cancer. And babies born a little late with big heads may be prone to allergies.

But these are associations--they are not cause and effect links.

Evidence for the Womb-Doom theory comes from animal research and a variety of population studies. Most compelling are the findings from the Dutch Hunger Winter of World War II, when part of Holland was virtually starved by occupying German forces from September 1944 until May 1945. Children born to women who were pregnant during that period have a higher risk of diabetes and schizophrenia. Males whose mothers faced starvation early in the pregnancy tend to be obese. Those whose mothers got adequate food in the first trimester, but not later in the pregnancy, have a greater chance of being svelte. In females, the starvation effect persists into the third generation. Women born to Dutch Hunger mothers are more likely to have growth-retarded babies when they get pregnant.

The Dutch experience highlights the catastrophe of famine and starvation that still affects parts of the world. But such extreme deprivation is not a problem for most women in the United States, and it would be a mistake to apply these findings to the ordinary pregnant woman who worries about eating a second piece of apple pie.

In other studies, British researcher David Barker has found an association between low birth weight--sometimes a marker for inadequate nutrition during pregnancy--and high blood pressure and heart disease in adulthood. Smaller babies had a greater risk compared to larger babies. At the same time, the vast majority of smaller babies still did not get heart disease.

Most important, the womb theory seems to discount the incredible resilience of fetuses and their ability to adapt and survive in the womb. What women eat and what they do (and don't do) during pregnancy is certainly important for the baby's health. But much more research is needed to see if specific conditions in the womb are part of a chain of causes that lead to chronic illnesses later in life.

Meanwhile, it would be a shame if the new womb science became fuel for the "blame-the-mom" syndrome. Beyond a certain point, a pregnant woman does not have control over everything that happens in the womb, notes Christian A. Chisholm, a specialist in high-risk pregnancies at Johns Hopkins University School of Medicine. "If a child develops heart disease, it's not something a woman should say: 'Gee, this is my fault, too!' Women are given enough to feel guilty for--they don't need this to add on top of it."