Considering how "informed" most vegetarians and vegans claim to be I am disappointed by the quality of the answers for this question!
In truth, and in practice there is a big difference between children born to vegetarians and omnivores:
http://news.bbc.co.uk/2/hi/health/869696.stm
Scientists have uncovered a way to increase the chances of giving birth to a baby girl - become a vegetarian.
A team from Nottingham University studied the impact of diet of pregnant women on the gender of their child.
They found that while the national average in Britain is 106 boys born to every 100 girls, for vegetarian mothers the ratio was just 85 boys to 100 girls.
http://news.bbc.co.uk/2/hi/health/286265.stm
A vegetarian diet could be responsible for genital defects in baby boys, according to BBC-funded research carried out by scientists in Bristol.
Researchers found that boys born to vegetarian mums are five times more likely to suffer from hypospadias, a condition that effects the male urethra.
In general, a balanced diet containing whole grains, fruits, vegetables, dairy products, and lean meats is the best diet for human beings. Vegetarian diets scrimp on vital nutrients and overdose on soy products which tend to raise the amounts of female hormones in the body. Male embryos do not react well to the higher hormone levels. More male embryos are miscarried leading to a higher rate of females being born.
Personally I would be more concerned with links to birth defects than the 85/100 ratio but to be safe I would limit the intake of soy immediately before getting pregnant and during the pregnancy.
On the other hand, ADULT men have a lot to gain from a high soy diet:
http://www.sciencedaily.com/releases/2004/03/040330090046.htm
A team of scientists has discovered that a little-known molecule created in the intestine when soy is digested is a natural and powerful blocker of a potent male hormone involved in prostate cancer and male pattern baldness. In fact, the molecule, equol, completely stops in its tracks the male hormone dihydrotestosterone (DHT), which normally stimulates prostate growth and causes male pattern baldness.
It is a good idea to do a little research before making major life changes...and look to REAL science sites that include citations in their stories. Many sites promote vegetarianism without citing reliable sources. As with any information....CONSIDER THE SOURCE.
Bad sites-(Lacking in citations and scientific evidence)
http://www.goveg.com/
http://www.vrg.org/index.htm
http://www.vegsource.com/
http://www.vegetariantimes.com/
http://www.vegsoc.org/
Also take note of how the website is presented and how many things they are selling.
Good sites(With appropriate citations and documentation)
http://en.wikipedia.org/wiki/Vegetarianism
http://news.bbc.co.uk
http://www.sciencedaily.com