There would less disposable diapers in land fills! Less people requiring medical attention as pregnancy requires a great deal of prenatal care as well as after birth visits for both mother and child.
On the other hand it would have some negative economic effects on businesses that develop products for infants( high chairs, car seats, cribs, diapers, baby food, baby wipes, infant clothing, formula, bottles, baby shower invitations and party supplies) These companies would have massive layoffs.
At some point in time there would be a year gap in students enrolling in school. Once the kids that were born the year before go from kindergarten to first grade there will not be a group of kids to follow them immediately which means some teachers will probably be laid off, nursery school closings, and so on.