This doesn’t happen for any reason other than efficiency—raising children is a chaotic job, and the family usually revolves around them. Decisions need to be made quickly, on the fly sometimes or more deliberately at other times. And more often than not, the primary caregiver is the person present to make those decisions.
And this, while efficient, will ultimately create a power imbalance that can kill any strong marriage.
So, make an effort to keep the decision making even in the marriage. If you are good at organizing your social life, then do that, but give your partner the opportunity to choose events. If they are good at managing the finances, let them do that, but continue to have input into where the money goes and why. Work together to make as many decisions about the kids and your family together.
Not letting either one of you be in charge is important.