Planning a pregnancy, raising children, and saying goodbye to sons and daughters isn't easy. A young woman who wasn't that long ago a child isn't going to be happy about having a baby with someone who just might not be the man of her dreams--especially when she has a lot of plans inside that mind of hers. The best thing a mature man can do in a situation like this is permit the young lady to live her life, not persuade her to have children. Imagine this, frequent doctor's appointments, weight gain, hair loss, a gassy newborn, sleepless nights, mommy blues, bills and more bills, diaper changes, and other things that she or her older partner may or may not be ready for at this point in their lives.
Yet, there are those men who will use manipulative mind control to get a young woman to at least consider having their babies for they know older women, possibly with children of their own are uninterested. It would make sense for a young woman to protect herself at all times especially if she is with a man who has communicated many times his desire to have children.
Now if you are in a relationship with a young woman who might want to have children with you, once again no pressure. If anything, one should be supportive in helping her get dreams accomplished (i.e. marriage might be a part of her plan) and who knows, the reward might be a baby one day--that is if she really wants to be a mom. However, there are many women who have no interest in being a mother particularly in their twenties and if this has been communicated, you would be better off looking for someone else who really does want to be a mom.