Applegate and Martyn welcomed Sadie into the world on 27 Jan., 2011. A rep for the actor confirmed the news in a statement at the time, telling Us Weekly and other outlets that "Mother and daughter are doing great." Martyn also announced the exciting news on Facebook, sharing that Sadie weighed 7 lbs., 8 oz.
Weeks later, Applegate gushed over motherhood in an interview with Us Weekly, saying that "just being in love" is her favourite part. "No offence to anyone that I know and love in my life, but you just really don't know love until you have that baby," she added. "You don't know. It's a whole 'nother ball game."
In August 2013, Applegate spoke to Access Hollywood about the possibility of having more kids. "I'm 41 years old and I don't know if I could do the whole, like, not sleeping thing again," she explained. "If I was 35, then maybe I'd have the energy but there's just, like, when I get up it hurts. Wait a couple of years and I'd be almost pushing 45. With, like, a newborn? I don't know."
"Some people can do it and I say, 'Hats off to you.' But that's just how I feel right now," she added. "Sadie's a very big ball of energy. I think we both want to make another Sadie. We watch this little person and she's so perfect and she enhances our life so much that you go, God — how could we not to produce more of these? But he's 44. We're both kind of like, eh, we're a little old and we don't know."
Over the years, Sadie has been on hand to support her mum on multiple occasions, including when Applegate received her Hollywood Walk of Fame star in November 2022. "The most important person in this world is my daughter," Applegate said during her speech at the ceremony. "You are so much more than even you know. You are so beautiful and kind and loving and smart and interesting. I am blessed every day that I get to wake up and take you to your school . . . You are my everything. Thank you for standing beside me through all of this."
This past January, Sadie accompanied her mum to the Critics' Choice Awards. Applegate commemorated the night with sweet photos on Twitter, writing, "Critics choice awards nails. It says Jen and Judy. And the other pic is of the best date ever … my rad daughter."