Mommy tweets: Beyoncé's post to Kelly Rowland's son Titan

Beyoncé shared this sweet photo on her Instagram of what appears to be her hand holding onto the fingers of Kelly Rowland's newborn son, Titan Jewell Witherspoon.

"There's no better feeling than holding my beautiful nephew," she captioned the photo. "I thank God for the honor of witnessing my sister's journey into motherhood. I've always dreamt of our little ones growing up together. I'm so thankful for our bond," she wrote, referring to her own daughter Blue Ivy.

Rowland, who named her son Titan after one of Saturn's moons, welcomed her first child this week with her husband, Tim Witherspoon. "Titan was born at 1:30 pm [PT] and weighed 7.5 lbs. We are blessed to report everyone is healthy and happy!" Rowland announced in a statement.

Blake Lively

Pregnant Blake Lively showed off her chic maternity style in this photo that was posted on the Instagram page of her lifestyle website, Preserve. The actress, who is expecting her first child with Ryan Reynolds, has loved dressing her new pregnancy curves in bold prints and bright colors.

Lively looks ready for winter in a Lindsey Thornburg Reverse Raven Trench Cloak, which just happens to be available on her website for the hefty price of $1,350. Hey, at least you could wear it long after you are no longer pregnant. She pairs the trench with black skinny pants and black boots.

Mariah Carey

It looks like Mariah Carey was getting an early start on Christmas shopping as she posted this photo of her standing in a toy store next to a toy soldier as her daughter Monroe held a toy doll in her hand.

Carey, who is separated from her husband of eight years, Nick Cannon, posted another sweet shot with Moroccan and Monroe as they cuddled with Edmond the Koala Bear at the Cleland Wildlife Park in Australia.

Robert Downey Jr.

Yes, we are aware he is not a celebrity mom, but we had to include Robert Downey Jr. in our list of buzzworthy celebrity moms (and dads) because he welcomed a daughter and gave her the sweetest name.

The name Avri is pronounced like Avery, while the middle name Roel is a combination of a Downey's father and his wife (Robert Downey Sr. and Rosemary), and his mother (Elsie) and his wife's father (Eliot). Very clever — although we could expect nothing less from Ironman.

Jessica Simpson

Jessica Simpson posted a picture of her mini-me daughter, Maxwell, as she tried on mama's lip gloss. With her blond hair and blue eyes, she is the spitting image of Simpson. "I need to move my lipgloss drawer! My favorites always get taken by this 2yr old!" she captioned the photo.

Simpson posted another picture of Maxwell, with the caption "Someone got into Mommy’s lip gloss. #poser."

One commenter, however, didn't believe that the toddler was able to apply her lip gloss with that much precision on her own.

"Steals her lipgloss. Really? All on her own? Has anyone else ever seen a toddler put that much lipstick on without it getting all over their face?" wrote one of Simpson's Instagram followers.

Well, maybe she had a little help from mom.

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