Kate Middleton is no stranger to being shamed, whether it's for being pregnant, for not being pregnant, for getting pregnant too quickly, and now, apparently, for being "too thin" to be carrying a child.
She was called "anorexic," "emaciated," and "malnourished," with others accusing her of lying about her condition.
First of all, if your most important citation is Wikipedia, you might want an additional source or two.
Secondly, Middleton has never admitted to having an eating disorder or eating in an unhealthy way. She has also never stated her weight, so believing she's 30 pounds underweight is an assumption based on zero facts.
Finally, accusing someone of lying about a sickness is absolutely cruel. Everyone experiences pregnancy differently, just like they do the side effects. Many women have talked about what Hyperemesis Gravidarum does to a pregnant person's body, so assuming she has it because she's "anorexic" is a load of BS.
She's not "too thin" to be pregnant.
Middleton is still in the early stages of her pregnancy, and besides that, she took a while to have a protruding belly in both her previous pregnancies. Pregnancy looks different on everyone, and until we have reason to believe otherwise, we have to assume that both she and the baby she's carrying are healthy.
People are also assuming she's exaggerating her symptoms.
According to women who have had the condition, it's hardly a walk in the park. One woman claimed to lose 12% of her body weight, had signs of sepsis, and severe esophageal and chest pain from throwing up so much. Yeah, but we're sure Middleton just felt like lounging around all day, Carly.
Shaming a pregnant woman (or any woman) for any reason — having a small belly, having a large belly, gaining weight in places other than her belly — is entirely uncool, and no one should have to put up with it.