You're delusional if you think being 50 lbs overweight is healthy for a developing baby. That's absolutely disgusting. That's like saying it's fine to have a few alcoholic drinks during pregnancy, it's not as risky as being a full blown alcoholic so who cares right? Maybe smoke a few cigarettes too, just don't smoke a pack a day. Gluttony is as big of a problem as any other vice. You'd have to be selfish to take even a slight risk when all you have to do is eat less. I'm pregnant with my 3rd child and always make sure I'm in the middle of the healthy BMI range before getting pregnant. Then I keep my weight gain in the middle of the healthy range during pregnancy. I couldn't live with myself knowing I put my children at risk of harm, even a slight risk, because I wanted to selfishly stuff my face instead of eating properly. Being close to underweight and not gaining enough is bad too, you're right. I actually gained weight for this last one because as you said, being underweight isn't healthy either and if I'd gotten bad morning sickness I would've ended up underweight. My highest BMI was actually 29.9 and I remember feeling like crap at that weight, even at 27-28 BMI. That's certainly not ideal for pregnancy. I lifted weights back then too, probably had a lower body fat percentage than the average lady at those BMIs but it still didn't matter. Being overweight is unhealthy, period. The extra body fat you're thinking of means the ideal body fat percentage is higher for women than it is for men. Healthy range for women is 21-31%, not including athlete and essential fat categories of body fat percentage which aren't ideal for pregnancy. For men that range is 14-24%. Look at this chart, 30% body fat isn't going to mean 50 lbs overweight for anyone. And that's the upper limit. https://files.catbox.moe/ussj53.jpg Compare to these examples of women at a 30 BMI https://height-weight-chart.com/504-170.html And 33 BMI https://height-weight-chart.com/510-230.html They aren't anywhere close to a healthy body fat percentage. Sure they aren't morbidly obese but again, would you want to have children with a woman who will smoke and drink occasionally during pregnancy just because their habits aren't as bad as chain smokers/binge drinkers? Why take the risk when they can easily choose to be healthy? If they can't lose a few lbs before conceiving a child to minimize risks then they care more about enjoying food than the life of their future children. And here is a better link about obesity during pregnancy and IQ: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5455002/ "More than a dozen observational studies have been conducted looking at the association between maternal BMI and cognitive function of the offspring during infancy and adolescence. These studies largely support a negative correlation between pre-pregnancy maternal obesity and child IQ, including poorer motor, spatial, and verbal skills]. In some cases, lower cognitive performance is also observed in children as a function of maternal weight gain during pregnancy, although the opposite has also been reported. Indeed, lower IQ and higher risk of intellectual disability are also related to low maternal BMI, suggesting that there is a U-shaped association between maternal weight and offspring cognitive performance."