Pregnant Hilary Duff (in a Bikini!) Cradles Sister Haylie's Daughter Lulu on Her Baby Bump

Hilary Duff is expecting a baby girl with boyfriend Matthew Koma

Hilary Duff is multitasking: Her baby bump doubles as a chair!

The pregnant Younger star spent her Labor Day weekend in the most adorable way: cradling her 3-month-old niece Lulu Gray on her growing stomach.

In the sweet snapshot Hilary shared on Instagram Monday, Lulu wore a rainbow shirt while her aunt, 30, rocked her baby bump in a black bikini.

“Look at this happy little lulu. I hope everyone had a nice holiday weekend! Felt so fortunate to spend it with our big growing family and friends,” she captioned the picture, added the hashtag, “#builtinseatforlu.”

Hilary Duff/Instagram

Hilary, who said on her Instagram Story that she was baking rosemary bread on Monday, also showed off her snacks. She wrote, “Ohhhh tried to keep it healthy with the veggies (anddd that’s a bowl of ranch haha).”

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RELATED GALLERY: Date Nights, Beach Outings and More: Pregnant Hilary Duff’s Cutest Baby Bump Moments

The Duff family certainly is expanding these days, as Hilary and boyfriend Matthew Koma announced in June that they are expecting a daughter. The actress also shares son Luca Cruz, 6, with ex-husband Mike Comrie.

Hilary’s sister Haylie Duff, who is mom to Lulu, also has 3-year-old daughter Ryan Ava Erhard with fiancé Matt Rosenberg.

In August, the mom-to-be opened up on Today about Luca’s thoughts on becoming a big brother. “He’s on the fence, but I think that everything will be fine when she arrives,” Hilary said.

RELATED VIDEO: Pregnant Hilary Duff Celebrates Younger Finale with “Shots Shots Shots” — of Green Juice

Hilary frequently shows off her baby bump. In one snap, the actress urged her daughter to “hurry it on up.” In another photo, she compared bellies with Koma and quipped, “I win.”

In July, the former Lizzie McGuire star discussed the challenges of pregnancy, writing alongside a bikini selfie, “The boobs are big the belly is big the body is big. Man … pregnancy is hard. Giving love to all mamas who make it look effortless.”

She continued, “This journey is hard as hell and also incredibly special. Lovely to have a little life inside and today dream of all the new adventures to come buuuut almost impossible to get my own shoes on … sick of getting up 9 times a night to pee and looking at this weird body in the mirror that is not my own at the moment.”

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