Blac Chyna is certainly no stranger to having her appearance endlessly picked apart, so it's no surprise she's now showing off just how much she's embracing the changes her body is going through during pregnancy. "Why should I watch my weight when I'm pregnant?" she asks in the caption of an Instagram photo posted earlier today. "My goal is to gain like 100 pounds this pregnancy," she explained in a Snapchat video last month. "Imma tear it up, and then I'm gonna snap back." Although this may be an extreme example, it does bring up a complex issue — why do doctors care so much about your pregnancy weight gain?Of course, gaining weight during pregnancy is normal and healthy. But gaining too much weight is associated with gestational diabetes, high blood pressure, and complications during delivery. So, for all of these reasons and more, the American Congress of Obstetrics and Gynecologists and the Institute of Medicine advise that people who are pregnant gain no more than a certain percentage of their pre-pregnancy weight. According to those recommendations , underweight women are supposed to gain between 26 and 40 pounds, women with normal weights should gain between 25 and 35 pounds, overweight women should gain between 15 and 25 pounds, and obese women should gain no more than 20 pounds.However, although experts may advise sticking within these strict ranges, the reality is that many women — up to 50% — gain more than the recommended amounts. So we're faced with the challenge of balancing those rigorous rules with the real-world fact that, despite our best efforts, most of just aren't going to follow them. And, of course, there are the well-known flaws in the BMI measure upon which all of these recommendations are based.Plus, lurking in the background of all of this is our society's overwhelming and shame-filled obsession with weight gain. This only intensifies during and after pregnancy, as magazine covers pressure women into feeling like they need to get back their "pre-baby body," as if they're somehow now less than the perfectly normal humans they have always been.So while we wouldn't advise you to go against these established guidelines without checking in with your own doctor, we also wouldn't advise you to stress the eff out about them either. And Blac Chyna's clearly got that part covered.