Car Seat Accessories

Because the plastic and foam degrade over time. Car seat bases rely on rigid plastic and energy-absorbing foam to spread crash forces away from your baby. Heat cycles, UV exposure, and everyday wear slowly make those materials more brittle, which weakens that protection over time. Manufacturers stamp a date of manufacture on the base and the actual car seat and certify performance for a set window (typically 6 to 10 years), after which they can't guarantee how the base or seat will hold up in a crash. It’s important to note that some seats, like Babyark, may never expire.

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When your baby fits the harness snugly without it. The exact cutoff varies by seat: Nuna PIPA calls for removal around 11 lbs, while UPPAbaby Aria seats use the insert up to about 4 months. Check your seat's manual for the exact threshold. The underlying test is the same across brands: if your baby fits the harness snugly without the insert, it's done its job.

Yes for newborns; your car seat already includes one. Every infant car seat sold at Modern Nursery ships with the insert designed for that specific seat, sized for newborns and small babies. Use it from birth until your baby fits the harness snugly without it, typically around 11 lbs or 4 months depending on the model. Skip aftermarket inserts since they aren't crash-tested with the seat and can throw off proper positioning.

Only if you're pairing two different brands. Same-brand travel systems usually click together or come with the adapter included, so there's nothing extra to buy. You'll need to buy one separately for cross-brand pairings, like a Nuna Pipa rx seat with an UPPABaby Vista stroller or a Chicco KeyFit with a Bumbleride Indie. Travel system bundles from Modern Nursery already have the right adapter in the box.