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.
Together, the egg and sperm result in a fertilized egg, known as a zygote, which contains all 46 chromosomes. Half the chromosomes come from the father, and half come from the mother. The process of meiosis and fertilization result in every generation having the same number of 46 chromosomes. The process also takes place in animals and plants. Oscar Hertwig, a German biologist, first observed the process of meiosis in 1876 as he studied the eggs of sea urchins, Wikipedia notes.