Having kids is a hugeee commitment that many people bravely take on during their lives. Despite all the parenting books and movies made about family life, having a kid is far too chaotic or unpredictable for anyone to be fully prepared. Plus, since people are consistently pressured into "following social norms" and having kids, sometimes parenthood is framed as "tough, but rewarding" as to not scare folks out of doing it.
Many lessons on parenthood are taught in a "trial by fire" manner. Perhaps, people are afraid of admitting their mistakes and shortcomings because they don't want to be seen as unfit parents. But, it doesn't need to be that way! Transparency and honesty are key in helping future parents find their footing.
Perhaps, you wish you had been better prepared for dealing with postpartum depression after having your baby. You watched your friends become shiny, new moms who seemed happy and somehow put together. You felt ashamed of your depression and like you were totally alone. Looking back, you wish you had been kinder to yourself and opened up to your loved ones.
Or, maybe you wish you had had more conversations with your partner about how your relationship could/would change as a result of having kids. You never anticipated how much your romantic relationship would change, and the process has been jarring.
Or, perhaps you wish you had become a parent with fewer preconceived notions about what having a kid should look like. With your first kid, you spent so much time comparing yourself and your kid to your friends and their kids that you were constantly stressed. Was your kid falling behind already? Were you doing something wrong? In hindsight, you wish you had known that not everything needs to be a competition.