Westminster Larger Catechism in modern English question number forty-seven:
Q. 47. How did Christ humble Himself in His conception and birth?
A. Christ humbled Himself in His conception and birth in that, even though He was from all eternity the Son of God in the bosom of the Father, He was pleased to become the son of man in the fullness of time, being made of and born by a woman of low status in circumstances of more than ordinary abasement.