This is the 16415th most frequent Russian word.
рождением
"Рождением" means "birth" in English.
The word 'рождением' is used in instrumental case to denote the means or cause of the happiness.
С рождением ребенка семья стала намного счастливее.
With the birth of the child, the family became much happier.
The word 'рождением' is paired with 'с' to indicate the occasion being celebrated.
Он поздравил её с рождением сына.
He congratulated her on the birth of her son.
The word 'рождением' contextualizes the concept of birth or beginning in connection to the subject.