If a mother was born in a foreign country, and the father was born and is a US citizen, they then have a female child. Is the child 1st generation even if the father is 4th generation?

My question is how is a generation figured out. If the father is an american, 4th generation, and the mother is from the Phillipines, they have a baby girl born in the USA, does the generation count come from the mother or the father. In other words, would the girl child be a 5th generation because of her father, or a first generation because of her mother. Thank you.