Mommy tweets: Paulina Gretzky, Kate Middleton, Christina Aguilera, Kendra

Paulina Gretzky and pro golfer Dustin Johnson welcomed a baby boy and shared this sweet first photo on Instagram.

"Happiest day of our entire lives was welcoming our sweet baby boy into the world 1.19.15," she captioned the photo, which shows her and Johnson looking at their son who is wrapped in a baby blanket.

Johnson shared the same photo on his own Instagram page with the caption, "We are so blessed to have a happy and healthy baby boy."

No word yet on the name of the baby boy, who just happens to be the grandson of NHL legend Wayne Gretzky. TMZ is reporting that the baby name does start with the letter T, which is a Gretzky tradition as Wayne's sons are named Tristan, Trevor and Ty.

"We sincerely appreciate the outpouring of love and support we have received and plan to release further details in the coming days!" Johnson said in a statement.

Gretzky, 26, shared this picture last month as she celebrated her baby shower surrounded by friends.

Johnson has not only been gearing up to be a new dad, but also to return to competitive golf as he took a voluntary leave of absence last July after reportedly testing positive for cocaine use. He has since denied that as the reason for his absence.

"I have issues. But that's not the issue," he said. "I am starting to become the person I want my kids to look up to."

Christina Aguilera

Christina Aguilera shared the first photo of her 5-month-old daughter, Summer Rain. Wearing a dress with a white lace diaper that has "Lil Diva" monogrammed on the back, Summer looks like she is getting ready to crawl off.

"Watch out…another one's getting ready to conquer the world! #driven #diva2," she captioned the photo.

Aguilera, who is gearing up to return to The Voice, also has a 7-year-old son named Max with her ex-husband.

Kate Middleton

Kate Middleton is on Twitter… sort of. Kensington Palace has a new Twitter account and they are sharing plenty of candid shots of the pregnant Duchess of Cambridge, along with Prince William and Prince Harry.

This is a cute shot of Middleton: 

As is this one:

I wonder what she is saying here. I'm sure it is something fabulous.

Reese Witherspoon

We love celebrity mom Reese Witherspoon's social media accounts because she often posts selfies with other celebrities — so we kind of feel like we have her fabulous life and are invited to all these amazing parties. Case in point: This selfie, with Jennifer Aniston and Cheryl Strayed, who just happens to be the author and the person that the movie Wild is based on.

Although in other ways, Witherspoon is just like us — like when she is potty training her son Tennessee.

Kendra

Kendra Wilkinson posted a rare photo of her daughter Alijah. What a cutie.

The reality star, who has been going through a tough time since finding out her husband Hank Baskett cheated on her with a transsexual model, tweeted that she is already back to her pre-baby goal weight.

"Just weighed myself and I'm back to pre lil Hank weight. Haven't been here since then," she tweeted, using the hashtag "fit for 30."

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