3 Chicco KeyFit 30 infant car seats installed in a 2007 Volvo XC90
Please note that MANY (if not the majority of) vehicles can not accommodate 3 infant car seats across the back seat. While it is possible to simply rest all three infant seats side by side, once you try to install one or two it becomes obvious that there is not enough room for the other/s due to the layout of the back seat. Due to 60/40 splits and other divisions of the back seat in many vehicles, you are often not dealing with three equally proportioned seats - but rather one larger seat (the 40 side - which is 40% of the back seat) and two seats that are each only 30% of the back seat.
Many people will assume that the width of the back seat is the amount of room they have to work with - when this is almost never the case. Because the lower anchors (part of the LATCH system) and the vehicle's seat belt usually start several inches away from the door, it makes it impossible for the car seat on the side to sit next to the door - rather, it is forced to sit several inches into the car. As you can see from the photos to the right - there is enough room to fit a large fist between the Chicco car seat and the Volvo door frame. Short of installing the car seat loosely, there is no way to get the car seat to sit closer to the door. In some vehicles, installing the car seat using the seat belt instead of the lower anchors allows you to install it an inch or two closer to the door - and that inch or two might make all the difference between fitting all the seats and not.
Will the Driver Have Enough Room to Drive - Why the Carrier Handle Position Matters
Another issue with infant seats is that not only do they take up room in the back seat - but by virtue of the fact that they lay semi-reclined, they take up leg room for the person sitting in front of the car seat (i.e. the driver or front passenger). When installing an infant seat behind the driver, it is not enough to make sure the car seat is installed securely in the back seat - but also that the driver has enough room to drive safely and ideally comfortably. Many infant seats require the carry handle to be placed either in the "store" position (at the top of the carrier) - which often makes the car seat take up an additional several inches of space front to back. Finding an infant carrier that allows the handle to be placed in the "carry" position while in the car will allow the person sitting in front of the car seat the most room. Please see this blog post with tip sheet for further info on the carry handle position - including a chart of the permissible handle positions for current and recently discontinued infant seats.
For example, the Britax Chaperone is a fantastic seat for preemies - but because it is almost 1.5 inches wider (external dimensions) than the Chicco Key Fit and takes up more room in the car front to back (meaning the driver has less room to drive) it may not work well for families with multiples depending on the vehicle.
Infant Car Seats for Babies LESS THAN 5 Pounds
10% of all babies in the US leave the hospital weighing less than 5 pounds. With multiples, there's an increased chance of taking home a baby weighing <5 lbs. Did you know that most infant seats are certified for babies 5 pounds and up. Therefore, finding a car seat that not only fits properly in your vehicle - but is also certified for the baby's weight - is of the utmost importance. Please see our tip sheet on preemies & small newborns for info on the starting weight for all the infant seats currently sold in the US, along with other pertinent info.