Back-to-back babies: Celebrities we love!

So, apparently there's a new trend in town, which Jessica Simpson's recent pregnancy announcement — just seven months after her baby Maxwell was born — brought to the forefront.

Here's Jessica with Maxwell around the time she made the big announcement. Her multi-million-dollar deal with Weight Watchers notwithstanding, the star was pregnant again, and fast!

Since Jessica's reportedly due in the summer, Maxwell will be just a little over a year older than her younger sibling.

Click on for more back-to-back celebrity babies!

Just before Jessica Simpson got us talking about back-to-back babies, there was Tori Spelling, of course. She shocked us all when she announced her fourth pregnancy just five months (if that) after she gave birth to her daughter Hattie, in October 2011.

Baby Finn was born in August 2012, making him a mere 10 months younger than Hattie.

"[Hattie] are 10 months apart, so for me, it's almost like having twins!" Tori told Access Hollywood. "It's a lot of work. It's not the fact of having four kids, it's just having two so close."

But having back-to-back babies was nothing new for Tori and hubby Dean McDermott. Their older kids, Liam, 5.5, and Stella, 4.5, are just 15 months apart.

Even before Tori Spelling, though, Britney Spears made headlines when she became pregnant with Jayden James, 6.5, shortly after giving birth to her first child, Sean Preston, 7.5.

Both born in September, the two boys are almost exactly one year apart.

Cute dog, eh? See more celebrity families and their pets!

Love this family!

Australian actor Naomi Watts and her long-time partner, actor Liev Schreiber, had their adorable blondies so close together: Alexander (aka Sasha), 5.5, is just 17 months older than his brother, Samuel, 4.

Check this couple out at this year's Golden Globes Awards — gorj!

Supermodel/Project Runway host Heidi Klum had three kids back to back! OK, let's see if I can this straight.

She gave birth to her first child (with Flavio Briatore), Leni, in May 2004. 16 months later (September 2005), she and ex-hubby Seal welcomed their son Henry. 14 months after that (November 2006), she and Seal welcomed their second son, Johan.

Whew! I can't imagine. Of course, Heidi bounced back quickly (and famously) every time. Later, in October 2009, Heidi and Seal welcomed their fourth child, Lou.

See more celebrities who have lots of kids!

Camila Alves and Matthew McConaughey have three children. Their first two, Levi, 4.5, and Vida, 3, are almost exactly 18 months apart. 

Camila and Matthew just welcomed their third child, Livingston, six weeks ago.

"It's getting to be more of a circus," Matthew told Access Hollywood of his newly expanded family.

See more of Hollywood's "older" dads!

Singer Usher and his ex-wife, Tameka Foster, had these two little guys back to back. This photo's a little old, but it's adorable. Usher Raymond V and Naviyd Ely Raymond are now five and six years old, respectively — only 13 months apart.

Read parenting quotes from Usher and other celebrities who are single parents!

Mark Wahlberg and his wife, Rhea Durham, have four kids — Ella, 9.5, Michael, 6.5, Brendan, 4.5, and Grace, 3. The younger two, Brendan and Grace, are just 16 months apart.

Mark's photo'd here taking the boys to play basketball in Brentwood, California. Cute kids!

See more affectionate celebrity parents!

Denise Richards had two daughters back to back with ex-hubby Charlie Sheen — Sam, 8.5, and Lola, 7.5. They're approximately 15 months apart.

Denise adopted her third daughter, Eloise, in June 2011.

See more of the most buzzed-about celebrity adoptions!

British singer Lily Allen gave birth to her second child, Marnie Rose, back in January — just 13 months after her first child, Ethel Mary, was born.

It’s Always Sunny in Philadelphia married costars Kaitlin Olson and Rob McElhenney have two sons — Axel Lee, 2.5, and Leo, 10 months — just 19 months apart.

I know I promised less than 18 months apart. But what's one month (...and "less than 19 months apart" sounded odd up there in the description). Besides, look how cute!

Donald Trump, Jr., and his wife, Vanessa, have a very busy household.

They have four kids — Kai, 5.5, Donald, 4, Tristan, 16 months, and Spencer, 4 months. And wow, if my calculations are correct, Tristan and Spencer are only 12 months apart.

(You know I love Donald Trump's The Apprentice.... I hear the new season's going to be awwwe-some!)

New Kids on the Block singer Joey McIntyre and his wife, Barrett Williams, have three kids together — Griffin, 5, Rhys, 3, and Kira, 21 months. Rhys and Kira are only around 17 months apart.