You should install your car seat about three to four weeks before your due date, which puts most parents in the 35- to 37-week range of pregnancy. This gives you enough time to get the installation checked by a professional and make adjustments without the pressure of labor starting any day. Kaiser Permanente recommends choosing a car seat during your second trimester and having it installed well before your due date.
Why Earlier Is Better Than Later
The main reason not to wait until the last minute is that about 1 in 10 babies in the United States arrives before 37 weeks. In 2022, the preterm birth rate was 10.4%, according to the CDC. If you plan to install the seat at 39 weeks and your baby comes at 36, you’re caught without one. Installing by 35 weeks covers most preterm scenarios and gives you a comfortable buffer.
There’s also a practical reason: most parents don’t get the installation right on the first try. Studies consistently show that the majority of car seats have at least one installation error. Giving yourself a few weeks means you can have a certified technician inspect it, fix any issues, and feel confident before the baby arrives.
What to Install and What to Wait On
Most infant car seats come in two pieces: a base that stays buckled into the car, and a removable carrier that clicks into it. You only need to install the base ahead of time. The carrier stays in your house (or gets attached to a stroller) until you’re actually heading to the hospital.
The base attaches to your car using either the seat belt or the LATCH system (metal anchors built into most vehicles made after 2002). Once it’s locked in and adjusted to the correct angle, it stays put. When you’re ready to drive with your baby, you place the infant in the carrier inside your home, carry it out to the car, and click it into the base. You should hear an audible click confirming it’s locked in. This system means you’re not re-threading a seat belt around the car seat every single trip, which dramatically reduces the chance of a loose or incorrect installation over time.
Getting the Installation Checked
A professional inspection is one of the most valuable things you can do before your baby arrives. Certified Child Passenger Safety Technicians (CPSTs) will check that your base is at the right angle, that the seat belt or LATCH attachment is tight enough, and that the harness is properly adjusted for a newborn. The inspection is almost always free.
There are three main ways to find a technician near you. Safe Kids Worldwide hosts car seat check events through local coalitions around the country. You can also search for individual technicians through the National CPS Certification Program’s online directory, filtering by location, language, or special needs training. The National Highway Traffic Safety Administration maintains its own directory of inspection stations as well. Fire stations and police departments sometimes offer checks too, though not every one has a certified technician on staff, so call ahead.
Plan to schedule your inspection for a week or two after you install the seat yourself. That way you’ve already done your best attempt, and the technician can show you exactly what needs fixing rather than doing the whole thing for you. You’ll learn more and be better prepared to reinstall it if you ever need to move it to a different vehicle.
What Happens at the Hospital
Hospitals will not discharge a newborn unless there’s a car seat available. While policies vary by hospital, NHTSA recommends that every hospital have a formal child passenger safety discharge policy. This typically includes educating parents on car seat use and installation, and referring families to community resources if they need help.
For premature or low birth weight babies, hospitals generally perform a car seat tolerance screening before discharge. A nurse or technician places the infant in their own car seat (at the angle the manufacturer specifies) and monitors them for a set period to make sure the baby can tolerate the semi-reclined position without breathing or heart rate problems. This is one more reason to have your car seat ready early: the hospital needs your specific seat for this test. If your baby is born early and you haven’t purchased or installed one yet, you’ll be scrambling during an already stressful time.
A Simple Timeline
- Second trimester (weeks 14 to 27): Research and purchase your car seat. Read the manual and your vehicle’s owner manual for the section on child restraints.
- Weeks 35 to 37: Install the base in the back seat. The center position is safest if your car allows a secure installation there; otherwise, either outboard rear seat works.
- Weeks 36 to 38: Have a certified technician inspect the installation. Adjust harness straps to the lowest slot setting for a newborn.
- Hospital day: Bring the carrier portion inside, buckle your baby in, and click it into the pre-installed base.
If you’re expecting twins or need seats in multiple vehicles, build in extra time. Each base needs its own inspection, and coordinating schedules with a technician can take a week or more depending on your area.