Under the Highway Traffic Act, children must use a forward-facing child car seat when they weigh between 9 kg and 18 kg (20 to 40 lb.) You need to use a forward-facing child car seat until your child weighs at least 18 kilograms (40 lb.). This is a minimum requirement.
only one sperm can enter an egg (first come first serve) only one egg can be fertilized at a time Answer Actually 2 or more can but the baby won't make it to birth. My daughter died at 16 weeks. I had the baby tested and she had been fertilized by 2 sperms. I agree with this answer.
Sperm contains 23 chromosomes. An egg contains 23 chromosomes. The zygote (a fertilized egg) contains 46 chromosomes. Yet, it is also important to consider that the egg completes meiosis before joining with the sperm, thereby shedding half of its 46 chromosomes into a polar body that adjoins the zona pelucida lining.