"Joy, would you please sit down!"
"Honey what's wrong?"
"JOY YOUR DUE DATE IS LESS THAN A WEEK AWAY FOR THE LOVE OF GOD PLEASE STOP MOVING."
When they chose Joy to carry their baby(actually THEIR baby! Science is awesome), Sadness thought it would be a chance for Joy to take a break. To slow down.
Oh the mistake she made. You couldn't keep Joy down with an 18 wheeler.
Joy continued to bustle around the house the entire pregnancy, giving Sadness a minor hernia each time she got to close to a desk, only for her to gracefully dance away. Jesus, aren't pregnant women supposed to be stuck in bed? Or at least have mood swings? The only thing about Joy that changed was the size of her belly. Not that Sadness minded. Sure she worried enough for both of them, but those moments when she was entering a room and caught Joy rubbing her bigger-than-normal midsection and smiling were worth more than a world made of gold.
A sharp squeak brought Sadness out of her thoughts. Refocusing, she saw Joy had stopped on a dime, and the squeaking noise was her shoe. Sadness looked into Joy's eyes, and she knew. No words needed to be said. She jumped up, grabbed Joy's hand, and calmly escorted her to their car.

Joy's labor was the most painful thing either of them had ever experienced. For Joy, the reason was fairly obvious. She was effectively pushing a watermelon out of her birth canal. It was the most painful day for Sadness, however, because Joy broke three of the bones in her hand during the process. She couldn't actually hold her child for a week after the surgery(something Joy apologized incessantly for and promised to make it up to her). She refused to let the doctors take her out though. She just worked her broken hand out of Joy's' grip, and let the taller woman grab her arm instead. Sadness was even worried for a while she's break that too. But Joy refused both a C-section and an epidural, even after the broken hand thing. She insisted she could do it. And she did. After hours of pushing and screaming and no breaks, Joy was holding her baby and the doctors were bodily dragging Sadness from the room. "The name we agreed on?" She called out, hooking her foot on the doorframe for the last few seconds she needed.
"Of course!" Joy called back as they unhooked Sadness and took her away. Turning to their baby, she said "Welcome to be world, little Riley."

"Joy, please sit down."
Joy, ignoring Sadness, continues to pace the room and bite her fingernails. "You're due date is a week past, dear. I'm nervous!"
"Joy."
At Sadness's tone, Joy rushes over, ready to do anything Sadness asks. Sadness would be lying if she said she didn't enjoy having this control over her living hurricane of a wife. And sure, before Joy was always willing to help. But when she became pregnant, Joy practically became her slave. Anything done, no questions. Sadness was a little worried she could ask Joy to kill someone and Joy would reply "How do you want it done?"
Sadness raised her hand. Joy took it and prepared to help Sadness up, but Sadness pulled her down instead, leaning her head on Joy's shoulder.
"Breathe. Relax. The baby will come soon."
No sooner had Joy followed the instructions than Sadness gripped her arm like a life preserver.
"Looks like she will be here much sooner than you think." Sadness said, giving Joy a smile. But when she saw the panic starting to form in Joy's eyes, she grabbed her head and said "Calm down. It's OK. We've practiced this. Now, help me up."

Joy had never heard Sadness scream like that. I mean yeah, there were the times they were having sex. Sadness screamed plenty during that. But this scream was very different. It sounded like someone had stuck a hot poker in her stomach. Which might've been what it felt like for all Joy knew. She begged Sadness to take a C-section, or at least an epidural. Interestingly, Sadness wasn't really in the mood for talking at the time. So she just sat there, holding her wife's hand and making sure she didn't pass out. It felt like it took half a century to Joy. For Sadness it must have felt like eons. But eventually it was over. The umbilical cord was cut, and Sadness was holding their newborn baby. Joy desperately wanted to go to her, but she wanted to save the look on Sadness's face forever first. Taking a quick picture(that she would later make her phone wallpaper for the next 9+ years), she went over to Sadness and stood next to her.
"Any last minute qualms about the name?" She asked, looking adoringly at her child.
"Of course not." Joy replied.
"Good. I wouldn't let you change it anyway. Riley is the perfect name."