Why isn't it safe? Well, the carseat is certified to hold up to 20-35 lb rear facing, depending on the model. If you are leaning over the seat during a crash, your body will slam into the seat as well. Assuming you don't actually crush the baby, killing him/her with your own body, you will still be putting a great deal more force on the seat than it was intended to handle. This could cause the seat to fail altogether, resulting in severe injury or even death. Best case scenario, your baby will be more injured than he/she would have been if your body hadn't interfered with the performance of the seat.
Additionally, it is not safe for YOU. It doesn't matter how dedicated you are to breastfeeding, your nursing relationship will end real fast if you are killed in a car crash! (For reference, I'm currently tandem nursing. I believe in extended nursing and child-led weaning.) In order to breastfeed a child in a car seat, you must move your own seatbelt out of the correct position. The lapbelt should ride low on your hips or across your thighs, while the shoulder belt should cross the center of your chest and lie across your shoulder. If either belt is improperly positioned, you increase the risk of internal injuries or even ejection from the vehicle & death! If you do manage to keep the belt in the correct position, but you are leaning forward or scootch your body forward, you are introducing slack which could allow you to be ejected during a crash. Even if you stay restrained by the belt, your body will move a lot more than it is supposed to, which will increase your risk of injury as well as increasing the risk that you will injure someone else.
Crash forces are
extreme! Even when properly restrained, a person moves a LOT during a crash. Seatbelts are designed to stretch (which is why you must replace any seatbelts which were in use during a crash).
This page* has 2 videos which illustrate my point. The first is the "5th percentile female test video." The second is the "BMW side impact test video." Both these videos give you an idea of how much movement is involved during a relatively low speed collision. The frontal/airbag test is done at 35 mph, while the side impact test is done at a mere 20 mph. Additionally, the 5th percentile dummy impacted on the steering wheel & airbag; if not for that, "she" would have moved significantly more. Both these dummies are 100% properly restrained. If there had been slack in the belt to begin with, the dummies would have moved even farther.
As another reference, government requirements for child safety seats limit head excursion, the distance the head moves forward) to a maximum of 28". An adult, who weighs much more than a child in a safety seat will also move farther. Scroll down to view
a picture of how far a child moves forward during a frontal impact. You can also view test footage for a front facing child seat. Remember, a full grown adult will probably move *more* than that!
When my daughter was 5 months and my son was 2.5, we moved from Des Moines, Iowa to Ft. Leonardwood, MO. It was a 7+ hour drive to visit my parents and ILs who still lived in Des Moines. We pulled over to nurse, stretch our legs, diaper change, etc as often as necessary. Yes, it made the trip "longer," but it was healthier and safer for everyone. You are *supposed to* pull over to take a break every 1-3 hours during long drives, whether you have a small child with you or not. You are *supposed to* change a wet diaper as soon as it is wet, whether it is going to leak soon or not. If you plan on stopping "often" and budget your time accordingly, it really is not a hassle.
Like I said, it doesn't matter how dedicated you are to nursing, your breastfeeding relationship will end real fast if one or both of you is killed in a vehicle collision!
