Upton, who is a first time mom to 10-month-old daughter Genevieve, admitted, "The hormones are crazy and no one talks about it." The 27-year-old model added, "The hormones after pregnancy, for me, were crazier than when I was pregnant, and it took forever for them to calm down, like months after breastfeeding."
Clarkson, who is mom to daughter River Rose, 5, and son Remy Alexander, 3, then noted, "Pumping is the worst!"
Upton agreed, before Clarkson added, "It's so painful. I don't care what anyone says."
Clarkson shared what happened after someone once tossed out some of her pumped milk in a bottle.
"I lost my ever-living mind — like I was a crazy person," she said. "Went in my closet and just collapsed on the floor and was crying, I was like, 'You have no idea how I had to work for that.' And really, there was like nothing in the bottle; I'm crazy. But, literally, it's just a hormonal period. I don't think people take that into account, especially when we're women in the public eye. It is a hard time."
Upton added, "Our energy is literally being sucked out of us, so you don't feel like yourself... it is so difficult and something people need to talk about more."
Louder for the people in the back!