We called in our advisory board member, Dr. Sarah Ballantyne, Ph.D., to help us answer this question! Sarah’s answer:
The issue with peas is complicated. They have some of the lowest levels of trypsin inhibitors, hemagglutinins and phytates of any legume, but the one study that looked at cooking and deactivation showed they needed two hours of cooking to completely deactivate (this study only looked at two hours, so we don't know if they can be deactivated more rapidly).
Generally, the low levels of antinutrients in peas aren't considered a big deal for healthy adults, which is why peas typically get a pass on Paleo. But phytohemagglutin, which is present in small amounts in peas, is known to change gut morphology in rats. (It’s used as a model of something called precocious gut maturation, an adaptation to solid foods before natural weaning, that protects mammal infants if they lose their mother, but it’s a different maturation process than normal.) That may simply imply that it's better for older babies, say at least seven months.