Studies done when Azadirachtin (the primary active pesticidal ingredient in neem oil) was approved as a pesticide showed that when neem leaves were fed to male albino rats for 11 weeks, 100% (reversible) infertility resulted.[citation needed]
Neem oil and other neem products such as neem leaves and neem tea should not be consumed by pregnant women, women trying to conceive, or children.[citation needed]
There is some evidence that internal medicinal use may be associated with liver damage in children.[2]
Quoted from http://en.wikipedia.org/wiki/Neem_oil